JP2006338925A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suitable fuel cell system which has a superior durability, power generation efficiency, and stability of output voltage value at normal power generation operation, and in which air bleed amount can be accurately increased, by accurately comprehending the performance deterioration of the anode catalyst of the fuel cell, using a simple constitution. <P>SOLUTION: This fuel cell system 100 is provided with a control part 20 that controls the fuel cell 15 which generates electric power by using an oxidizer gas supplied by the oxidizer gas supply part 17, and a gas in which a fuel gas containing a reformed hydrogen gas supplied by the fuel gas supply part 7 is mixed with the air supplied by the air bleed mechanism 12. The control part 20 diagnoses the performance reduction of the anode catalyst of the fuel cell 15 at least at either time of start-up operation or stopping operation, the air bleed mechanism 12 is controlled based on the results of the diagnosis, and the supply amount of the air to the fuel gas is made to be increased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell system used for portable devices, electric vehicles, household cogeneration systems, and the like, and more particularly to a fuel cell system that increases the amount of air bleed in response to a decrease in the performance of an anode catalyst.

  Conventionally, a fuel cell system capable of high-efficiency small-scale power generation is easy to build a system for using thermal energy generated during power generation. Development is progressing as a power generation system.

  In a fuel cell system, during a power generation operation, a fuel gas and an oxidant gas are respectively supplied to a fuel cell stack (hereinafter simply referred to as a fuel cell) disposed as a main body of the power generation unit. Then, in the fuel cell, hydrogen in the supplied fuel gas and oxygen in the oxidant gas are used, and a predetermined electrochemical reaction proceeds. As the electrochemical reaction proceeds, the chemical energy of hydrogen and oxygen is directly converted into electrical energy. As a result, the fuel cell system outputs power toward the load.

  The configuration and operation of a conventional fuel cell system will be outlined below.

  FIG. 10 is a block diagram schematically showing a part of a general configuration of a conventional fuel cell system. FIG. 10 shows a configuration in which reformed gas generated by reforming city gas is used as fuel gas and air is used as oxidant gas. In the following description, “CO” means “carbon monoxide”.

  As shown in FIG. 10, the conventional fuel cell system 200 includes a raw material flow rate adjustment valve 101 and a desulfurizer 102. The raw material flow rate adjusting valve 101 adjusts the amount of city gas supplied from the city gas supply means to the desulfurizer 102. Further, the desulfurizer 102 removes an odorant such as mercaptan or dimethyl sulfide contained in the city gas that has passed through the raw material flow rate adjustment valve 101.

  The fuel cell system 200 includes a reformer 103, a transformer 104, and a purifier 105. The reformer 103 uses the city gas from which the odorant has been removed after passing through the desulfurizer 102 to generate a reformed gas by a steam reforming reaction. Further, the transformer 104 reduces the concentration of carbon monoxide contained in the reformed gas generated by the reformer 103 by a shift reaction. The purifier 105 further reduces the concentration of carbon monoxide contained in the reformed gas that has passed through the transformer 104 by a selective oxidation reaction. At least the reformer 103, the transformer 104, and the purifier 105 constitute a fuel reforming unit 106. As shown in FIG. 10, water is supplied from the water supply means to the reformer 103 by a reforming water supply pump 107. Further, the supply amount of air from the air flow rate adjusting unit 111 described later to the purifier 105 is adjusted by the selective oxidation flow rate adjusting unit 108.

  The fuel cell system 200 includes a fuel cell 109. The fuel cell 109 generates power using the reformed gas generated by the fuel reforming unit 106. As the fuel cell 109, for example, a polymer electrolyte fuel cell is provided. This polymer electrolyte fuel cell includes a polymer electrolyte membrane having proton conductivity. The polymer electrolyte membrane includes platinum catalysts (anode catalyst and cathode catalyst) on both sides thereof. In such a polymer electrolyte fuel cell, a catalytic reaction in which hydrogen contained in the reformed gas is converted into protons and electrons proceeds on the anode catalyst by the catalytic action of platinum. At this time, protons move inside the polymer electrolyte membrane and reach the cathode catalyst. Electrons reach the cathode catalyst via an external load. On the other hand, on the cathode catalyst, a catalytic reaction of generating water from the protons and electrons that arrive and oxygen in the air supplied from the humidifier 112 described later proceeds due to the catalytic action of platinum. As shown in FIG. 10, the heat exchange unit 110 cools the fuel cell 109 that generates heat during the power generation operation.

  The fuel cell system 200 includes an air flow rate adjusting unit 111, a humidifier 112, and a combustor 114. The air flow rate adjustment unit 111 adjusts the amount of air supplied from the atmosphere to the selective oxidation flow rate adjustment unit 108, the humidifier 112, and an air bleed mechanism 113 described later. Further, the humidifier 112 heats and humidifies the air that has passed through the air flow rate adjusting unit 111 using high-temperature, high-humidity exhaust air that is discharged from the fuel cell 109. Further, the combustor 114 burns the exhaust reformed gas discharged from the fuel cell 109 using the exhaust air discharged from the fuel cell 109 and passed through the humidifier 112. Then, it is discharged outside the fuel cell system 200 as exhaust combustion gas.

  The fuel cell system 200 includes an air bleed mechanism 113. The air bleed mechanism 113 supplies the reformed gas generated by the fuel reforming unit 106 during the power generation operation with air that has passed through the air flow rate adjusting unit 111 before being supplied to the fuel cell 109 in a predetermined supply amount. With this air bleed mechanism 113, the fuel cell system 200 suppresses poisoning of the anode catalyst in the fuel cell 109.

  Specifically, the reformed gas generated by the fuel reforming unit 106 usually contains a small amount of carbon monoxide. This carbon monoxide easily binds to platinum, causing poisoning of the anode catalyst of the fuel cell 109. This poisoning of the anode catalyst significantly impedes the progress of the catalytic reaction using hydrogen on the anode catalyst. Therefore, air is supplied to the reformed gas by the air bleed mechanism 113 and oxygen is supplied onto the anode catalyst of the fuel cell 109. And the carbon monoxide couple | bonded with the anode catalyst is further oxidized using oxygen, and is converted into a carbon dioxide. As a result, carbon dioxide is desorbed from the anode catalyst and discharged together with the exhaust reformed gas to the outside of the fuel cell 109, so that poisoning of the anode catalyst in the fuel cell 109 can be suppressed.

  By the way, in recent fuel cell systems, in addition to the air bleed mechanism described above, a platinum-ruthenium alloy catalyst is used as the anode catalyst of the fuel cell in place of the platinum catalyst in order to impart CO poisoning resistance to the fuel cell itself. Used. According to the configuration using this platinum-ruthenium alloy catalyst, in addition to the poisoning suppressing effect by the air bleed mechanism, oxygen is also adsorbed and supplied onto the platinum from moisture in the reformed gas by ruthenium having oxygen adsorption ability. Therefore, poisoning of the anode catalyst in the fuel cell can be more effectively suppressed.

  However, in a fuel cell system that uses this platinum-ruthenium alloy catalyst as an anode catalyst, when the power generation operation is continued for a long period of time, or when the power generation operation is repeatedly started and stopped (hereinafter referred to as DSS operation). In this case, ruthenium is eluted, and the residual ratio of ruthenium in the platinum-ruthenium alloy catalyst is lowered, so that the CO poisoning resistance of the fuel cell itself is lowered with time. In this case, since the amount of air supplied to the reformed gas by the air bleed mechanism (hereinafter referred to as air bleed amount) is insufficient, poisoning of the anode catalyst of the fuel cell decreases with time, and the output voltage of the fuel cell The value decreases over time.

Therefore, during power generation operation, the concentration of carbon monoxide contained in the reformed gas temporarily increases, and the warning voltage is lower than the normal voltage value by a predetermined voltage value due to poisoning of the anode catalyst. When the value is lower than the value, the air bleed amount by the air bleed mechanism is increased by about 20 to 30%, so that the output voltage value of the fuel cell is recovered to a voltage value higher than the warning voltage value without stopping the power generation operation. A fuel cell system has been proposed (see, for example, Patent Document 1).
JP 2004-207135 A

  However, in the above-described conventional proposal, after the output voltage value of the fuel cell falls below a predetermined threshold value, the air bleed amount is increased and the output voltage value of the fuel cell is recovered to the predetermined voltage value. The output voltage value of the fuel cell fluctuates during operation. This fluctuation in the output voltage value of the fuel cell significantly hinders stable operation of an external load connected to the fuel cell system.

  Further, in the above-described conventional proposal, when the output voltage value of the fuel cell is below a predetermined threshold value and the air bleed amount is increased, the increased amount of the air bleed amount is accurately compensated for the performance degradation of the anode catalyst. It is difficult to increase the amount. In other words, for example, when poisoning of the anode catalyst has progressed due to a decrease in ruthenium in the platinum-ruthenium alloy catalyst, it is difficult to accurately grasp the residual rate of the ruthenium and accurately increase the air bleed amount. The reason is that even if the fluctuation value of the output voltage value of the fuel cell is detected during the power generation operation, the fluctuation value of the output voltage value does not accurately reflect the residual rate of ruthenium in the platinum-ruthenium alloy catalyst. It is.

  Also, if the increase in the amount of air bleed exceeds the exact increase to compensate for the decrease in ruthenium in the platinum-ruthenium alloy catalyst, the excess oxygen is simply the amount of hydrogen contained in the reformed gas in the fuel cell. In order to promote the combustion reaction, the amount of hydrogen that can be used for the power generation operation of the fuel cell is reduced. That is, excessive supply of oxygen to the fuel cell deteriorates the power generation efficiency of the fuel cell system.

  The present invention has been made in view of such circumstances, and it is possible to accurately grasp the performance degradation of the anode catalyst of the fuel cell with a simple configuration and accurately increase the amount of air bleed. An object of the present invention is to provide a suitable fuel cell system having durability, power generation efficiency, and stability of an output voltage value during normal power generation operation.

  In order to solve the above-described conventional problems, a fuel cell system according to the present invention includes an air bleed mechanism for supplying air, an oxidant gas supply unit for supplying an oxidant gas, and hydrogen by reforming a raw material. A fuel gas supply unit that supplies fuel gas, the oxidant gas that is supplied by the oxidant gas supply unit, and the fuel gas that is supplied by the fuel gas supply unit is obtained by the air bleed mechanism supplying the air. A fuel cell that generates power using a mixed gas of the fuel gas and the air, and at least the air bleed mechanism, the oxidant gas supply unit, the fuel gas supply unit, and the fuel cell to control start-up operation and stop A control unit that performs operation, wherein the control unit diagnoses a decrease in performance of the anode catalyst of the fuel cell during the start-up operation, and is based on a result of the diagnosis. There wherein by controlling the air bleed mechanism to increase the supply amount of the air to the fuel gas (claim 1).

  With this configuration, the control unit diagnoses a decrease in the performance of the anode catalyst of the fuel cell during start-up operation of the fuel cell system and increases the amount of air supplied to the fuel gas by the air bleed mechanism. It becomes possible to provide a fuel cell system with excellent output characteristics.

  In this case, a voltage difference between the output voltage value of the fuel cell and a predetermined reference voltage value when the control unit supplies the fuel gas having a carbon monoxide concentration exceeding that during normal power generation operation. Based on the above, the diagnosis is made (Claim 2).

  With such a configuration, the anode gas catalyst is supplied based on the voltage difference between the output voltage value when the fuel gas supply unit supplies fuel gas having a carbon monoxide concentration exceeding that during normal power generation operation to the fuel cell and a predetermined reference voltage value. Since performance degradation is diagnosed, the degree of performance degradation of the anode catalyst can be diagnosed extremely accurately. As a result, the amount of air supplied to the fuel gas by the air bleed mechanism can be increased extremely accurately, so that a fuel cell system having excellent durability and power generation efficiency can be provided.

  In this case, the fuel gas supply unit includes a transformer that reduces the carbon monoxide concentration of the fuel gas to a first concentration that is higher than or equal to a first temperature, and the temperature of the transformer is less than the first temperature. The fuel gas having a carbon monoxide concentration exceeding that during the normal power generation operation is determined by the control unit and the transformer reduces the carbon monoxide concentration of the fuel gas to exceed the first concentration. (Claim 3).

  With such a configuration, a fuel gas having a carbon monoxide concentration exceeding the normal power generation operation can be supplied to the fuel cell by using the configuration and operation of the conventional fuel cell system without providing any special equipment. It becomes possible.

  Further, in the above case, the fuel gas supply unit includes a purifier that reduces the carbon monoxide concentration of the fuel gas to a second temperature or higher and a second concentration or lower, and the temperature of the purifier is the second temperature. The controller determines that the temperature is lower than the temperature, and the purifier reduces the carbon monoxide concentration of the fuel gas so as to exceed the second concentration. The fuel gas is supplied (claim 4).

  Even in such a configuration, a fuel gas having a carbon monoxide concentration exceeding the normal power generation operation can be supplied to the fuel cell by using the configuration and operation of the conventional fuel cell system without providing any special equipment. It becomes possible.

  Further, in the above case, an air supply unit that supplies air to the purifier at a predetermined flow rate or more in order to reduce the carbon monoxide concentration of the fuel gas to the second concentration or more above the second temperature. The controller determines that at least the temperatures of the transformer and the purifier are equal to or higher than the first and second temperatures, and the air supply unit supplies the air at less than the predetermined flow rate. The fuel gas having a carbon monoxide concentration exceeding that during the normal power generation operation is supplied by stopping the supply (Claim 5).

  Even in such a configuration, a fuel gas having a carbon monoxide concentration exceeding the normal power generation operation can be supplied to the fuel cell by using the configuration and operation of the conventional fuel cell system without providing any special equipment. It becomes possible.

  The fuel cell system according to the present invention includes an air bleed mechanism for supplying air, an oxidant gas supply unit for supplying an oxidant gas, and a fuel gas supply for supplying a fuel gas containing hydrogen by reforming a raw material. The oxidant gas supplied by the oxidant gas supply unit, and the fuel gas and the air obtained by the air bleed mechanism supplying the air to the fuel gas supplied by the fuel gas supply unit. A fuel cell that generates electric power using a mixed gas; and at least the air bleed mechanism, the oxidant gas supply unit, the fuel gas supply unit, and a control unit that controls the fuel cell to perform start-up operation and stop operation. In the fuel cell system, the control unit diagnoses a decrease in performance of the anode catalyst of the fuel cell during the stop operation, and the air bleed mechanism is based on a result of the diagnosis. Controlled to increase the supply amount of the air to the fuel gas (claim 6).

  With this configuration, the control unit diagnoses the performance deterioration of the anode catalyst of the fuel cell during the stop operation of the fuel cell system and increases the amount of air supplied to the fuel gas by the air bleed mechanism. It becomes possible to provide a fuel cell system with excellent output characteristics.

  In this case, a voltage difference between the output voltage value of the fuel cell and a predetermined reference voltage value when the control unit supplies the fuel gas having a carbon monoxide concentration exceeding that during normal power generation operation. Based on the above, the diagnosis is made (claim 7).

  With such a configuration, the anode gas catalyst is supplied based on the voltage difference between the output voltage value when the fuel gas supply unit supplies fuel gas having a carbon monoxide concentration exceeding that during normal power generation operation to the fuel cell and a predetermined reference voltage value. Since performance degradation is diagnosed, the degree of performance degradation of the anode catalyst can be diagnosed extremely accurately. As a result, the amount of air supplied to the fuel gas by the air bleed mechanism can be increased extremely accurately, so that a fuel cell system having excellent durability and power generation efficiency can be provided.

  In this case, the fuel gas supply unit includes a transformer that reduces the carbon monoxide concentration of the fuel gas to a first concentration that is higher than or equal to a first temperature, and the temperature of the transformer is less than the first temperature. The fuel gas having a carbon monoxide concentration exceeding that during the normal power generation operation is determined by the control unit and the transformer reduces the carbon monoxide concentration of the fuel gas to exceed the first concentration. (Claim 8).

  With such a configuration, a fuel gas having a carbon monoxide concentration exceeding the normal power generation operation can be supplied to the fuel cell by using the configuration and operation of the conventional fuel cell system without providing any special equipment. It becomes possible.

  Further, in the above case, the fuel gas supply unit includes a purifier that reduces the carbon monoxide concentration of the fuel gas to a second temperature or higher and a second concentration or lower, and the temperature of the purifier is the second temperature. The controller determines that the temperature is lower than the temperature, and the purifier reduces the carbon monoxide concentration of the fuel gas so as to exceed the second concentration. The fuel gas is supplied (claim 9).

  Even in such a configuration, a fuel gas having a carbon monoxide concentration exceeding the normal power generation operation can be supplied to the fuel cell by using the configuration and operation of the conventional fuel cell system without providing any special equipment. It becomes possible.

  Further, in the above case, an air supply unit that supplies air to the purifier at a predetermined flow rate or more in order to reduce the carbon monoxide concentration of the fuel gas to the second concentration or more above the second temperature. The controller determines that at least the temperatures of the transformer and the purifier are equal to or higher than the first and second temperatures, and the air supply unit supplies the air at less than the predetermined flow rate. By stopping the supply, the fuel gas having a carbon monoxide concentration exceeding that during the normal power generation operation is supplied (claim 10).

  Even in such a configuration, a fuel gas having a carbon monoxide concentration exceeding the normal power generation operation can be supplied to the fuel cell by using the configuration and operation of the conventional fuel cell system without providing any special equipment. It becomes possible.

  In the above case, the control unit diagnoses the deterioration of the performance of the anode catalyst of the fuel cell during the stop operation as well as during the start operation.

  With this configuration, the control unit diagnoses the deterioration in the performance of the anode catalyst of the fuel cell at the time of start-up operation and also at the time of stop operation, so that a fuel cell system with even more excellent power output characteristics during normal power generation operation is provided. It becomes possible.

  In the above case, the fuel cell includes an anode catalyst on one surface of the polymer electrolyte membrane having proton conductivity and a cathode catalyst on the other surface, and at least the anode catalyst of the anode catalyst and the cathode catalyst includes A polymer electrolyte fuel cell comprising a platinum-ruthenium alloy catalyst (claim 12).

  With such a configuration, since the fuel cell is a polymer electrolyte fuel cell in which at least the anode catalyst of the anode catalyst and the cathode catalyst is a platinum-ruthenium alloy catalyst, the present invention can be suitably implemented.

  According to the fuel cell system of the present invention, it is possible to accurately grasp the performance degradation of the anode catalyst of the fuel cell and accurately increase the amount of air bleed to the fuel cell. Can be reliably eliminated, and damage to the polymer electrolyte membrane and deterioration of power generation efficiency can be reliably prevented.

  Further, according to the fuel cell system of the present invention, the performance degradation of the anode catalyst of the fuel cell can be accurately grasped by the simple configuration utilizing the configuration and operation of the conventional fuel cell system when the normal power generation operation is not performed. Therefore, it is possible to ensure the stability of the output voltage value of the fuel cell system.

  In other words, according to the present invention, it is possible to accurately grasp the performance deterioration of the anode catalyst of the fuel cell with a simple configuration and accurately increase the amount of air bleed. Excellent durability and power generation efficiency and output voltage It is possible to provide a suitable fuel cell system having a stable value.

  According to the present invention, since the life of the polymer electrolyte membrane can be extended by increasing the amount of air bleed into the fuel cell very accurately, the life of the fuel cell system is extended. I can also expect that.

  The concept of the present invention is directed to a fuel cell system that performs DSS operation in which power generation operation is repeatedly started and stopped.

  The present invention is also directed to a fuel cell system including a fuel reforming unit that generates reformed gas and an air bleed mechanism that supplies air to the reformed gas generated by the fuel reforming unit.

  In the best mode for carrying out the present invention, a fuel cell system using a platinum-ruthenium alloy catalyst as an anode catalyst will be described as an example.

  In this specification, the operation from the start of the fuel cell system to the start of power output is defined as the “start-up operation” of the fuel cell system. Further, the operation from the stop of power output to the stop of the operation of the fuel cell system is defined as the “stop operation” of the fuel cell system. The operation when the fuel cell system outputs power is defined as “normal power generation operation” of the fuel cell system.

  First, the basic operation concept of the fuel cell system, which is common in the first to seventh embodiments of the present invention, accurately grasps the performance degradation of the anode catalyst of the fuel cell and accurately obtains the increase amount of the air bleed amount. Will be described.

  In a fuel cell system using a platinum-ruthenium alloy catalyst as an anode catalyst, for example, when the DSS operation is performed, ruthenium in the platinum-ruthenium alloy catalyst is eluted, so that the residual ratio of ruthenium in the platinum-ruthenium alloy catalyst is changed over time. descend. That is, since the residual rate of ruthenium having oxygen adsorption ability and oxygen supply ability decreases with time, the CO poisoning resistance of the fuel cell itself decreases with time.

  By the way, in a fuel cell system using a platinum-ruthenium alloy catalyst as an anode catalyst, the poisoning of the anode catalyst uses the oxygen adsorption ability of ruthenium, the oxygen supply ability to platinum, and the air supply ability of the air bleed mechanism. Effective suppression. Therefore, in the case where the ruthenium residual rate in the platinum-ruthenium alloy catalyst decreases with time and the CO poisoning resistance of the fuel cell itself decreases with time, in order to suitably maintain the power generation performance of the fuel cell, It is necessary to accurately increase the amount of air bleed into the reformed gas by the air bleed mechanism in accordance with the decrease in the ruthenium remaining rate in the platinum-ruthenium alloy catalyst.

  On the other hand, in a general fuel cell system having a fuel reforming section, even if the temperature of the reformer in the fuel reforming section is a predetermined temperature for causing the steam reforming reaction to proceed, the transformation in the fuel reforming section is performed. When the temperature of the purifier is not a predetermined temperature for proceeding with the shift reaction, or when the temperature of the purifier in the fuel reforming unit is not the predetermined temperature for proceeding with the selective oxidation reaction, the reformer generated by the fuel reforming unit is generated. The quality gas contains carbon monoxide at a high concentration of 100 ppm or more.

  Also, the temperature of the reformer, the transformer, and the purifier in the fuel reforming section is a predetermined temperature for proceeding with the steam reforming reaction, a predetermined temperature for proceeding with the shift reaction, and a selective oxidation reaction. Even if the predetermined temperature is low, the fuel reforming unit generates a reformation when the amount of air supplied from the selective oxidation flow control unit to the purifier is insufficient, that is, when the stoichiometry in the purifier deteriorates. The quality gas contains carbon monoxide at a high concentration of 100 ppm or more.

  Therefore, in the present invention, the temperature inherent in the above-described fuel reforming unit is positively utilized, and the temperature of the transformer in the fuel reforming unit proceeds with a shift reaction during start-up or stop-operation of the fuel cell system. A reformed gas containing carbon monoxide at a high concentration that does not destroy the fuel cell and is not supplied during normal power generation operation when the diagnosis temperature is equal to or lower than a predetermined temperature for Intentionally supply the battery. Alternatively, when the temperature of the purifier in the fuel reforming section is a diagnostic temperature lower than a predetermined temperature for allowing the selective oxidation reaction to proceed, the concentration is high enough not to destroy the fuel cell and not to be supplied during normal power generation operation. A reformed gas containing carbon monoxide is intentionally supplied to the fuel cell from the fuel reformer.

  Alternatively, by actively utilizing the above-mentioned properties inherent in the fuel reforming unit, the temperature of the reformer, the transformer, and the purifier in the fuel reforming unit is steam during the start-up operation or stop operation of the fuel cell system. When the predetermined temperature for proceeding the reforming reaction, the predetermined temperature for proceeding the shift reaction, and the predetermined temperature for proceeding the selective oxidation reaction, the air from the selective oxidation flow control unit to the purifier The supply amount is reduced at a predetermined reduction rate. Alternatively, the supply of air from the selective oxidation flow rate adjusting unit to the purifier is stopped. As a result, the reformed gas containing carbon monoxide at a high concentration that does not destroy the fuel cell and is not supplied during normal power generation operation is intentionally supplied from the fuel reformer to the fuel cell.

  Further, as described above, when the reformed gas containing a high concentration of carbon monoxide is supplied from the fuel reforming unit to the fuel cell, the air flow rate adjusting unit is driven to supply air from the humidifier to the fuel cell.

  Then, when the reformed gas containing carbon monoxide and air are supplied to the fuel cell, the output voltage value of the fuel cell is measured, and based on the voltage difference between the output voltage value to be measured and a predetermined reference voltage value Thus, the ruthenium residual rate in the platinum-ruthenium alloy catalyst is accurately obtained. Then, the optimum increase amount of the air bleed amount to the fuel cell is accurately obtained according to the accurately obtained ruthenium residual rate. Thereby, in the fuel cell system, the power generation performance of the fuel cell is suitably maintained.

  Next, the basic operation of the fuel cell system, which is common in the first to seventh embodiments of the present invention, accurately grasps the performance deterioration of the anode catalyst of the fuel cell and accurately obtains the increase amount of the air bleed amount. The principle will be described in detail with reference to the drawings.

  FIG. 2 is a schematic diagram for explaining the principle for accurately obtaining the ruthenium residual rate in the platinum-ruthenium alloy catalyst. In FIG. 2, the vertical axis indicates the output voltage value of the fuel cell, and the horizontal axis indicates the concentration of carbon monoxide contained in the reformed gas.

  In FIG. 2, a voltage value E indicates an output voltage value of the fuel cell when pure hydrogen is supplied. In FIG. 2, the CO concentration C1 indicates the concentration of carbon monoxide contained in the reformed gas supplied to the fuel cell during normal power generation operation. The CO concentration C2 indicates the concentration of carbon monoxide contained in the reformed gas supplied to the fuel cell when the optimum air bleed amount is accurately obtained during start-up or stop-operation of the fuel cell system. .

  In FIG. 2, curve a shows the output voltage characteristic of the fuel cell when the ruthenium residual rate in the platinum-ruthenium alloy catalyst is 100%. Curve b shows the output voltage characteristics of the fuel cell when the ruthenium remaining rate in the platinum-ruthenium alloy catalyst is 80%. Curve c shows the output voltage characteristics of the fuel cell when the ruthenium remaining rate in the platinum-ruthenium alloy catalyst is 60%. Curve d shows the output voltage characteristics of the fuel cell when the ruthenium residual rate in the platinum-ruthenium alloy catalyst is 40%. Curve e shows the output voltage characteristic of the fuel cell when the ruthenium remaining rate in the platinum-ruthenium alloy catalyst is 20%. A curve f shows the output voltage characteristics of the fuel cell when the residual ratio of ruthenium in the platinum-ruthenium alloy catalyst is 0%.

  As shown in FIG. 2, when the residual rate of ruthenium in the platinum-ruthenium alloy catalyst is 100% (curve a), a fuel cell that can output a voltage value E upon receiving pure hydrogen is When a reformed gas containing carbon monoxide having a CO concentration C1, which is an allowable concentration during normal power generation operation, is supplied from the mass portion, a voltage value Ea1 is output. Further, when the ruthenium remaining rate in the platinum-ruthenium alloy catalyst is 0% (curve f), the fuel cell is supplied with a reformed gas containing carbon monoxide having a CO concentration of C1 from the fuel reforming section. Thus, the voltage value Ef1 is output. Here, as shown in FIG. 2, the voltage difference between the voltage value Ea1 and the voltage value Ef1 is ΔEaf1.

  On the other hand, as shown in FIG. 2, when the ruthenium remaining rate in the platinum-ruthenium alloy catalyst is 100% (curve a), the fuel cell has a CO concentration during start-up operation or stop operation from the fuel reforming section. By receiving the supply of the reformed gas containing C2 carbon monoxide, the voltage value Ea2 is output. Further, when the ruthenium remaining rate in the platinum-ruthenium alloy catalyst is 0% (curve f), the fuel cell is supplied with a reformed gas containing carbon monoxide having a CO concentration of C2 from the fuel reforming section. Thus, the voltage value Ef2 is output. Here, as shown in FIG. 2, the voltage difference between the voltage value Ea2 and the voltage value Ef2 is ΔEaf2. The voltage difference ΔEaf2 is larger than the voltage difference ΔEaf1 described above.

  In other words, if a reformed gas containing a high concentration of carbon monoxide is intentionally supplied to the fuel cell, the decrease value of the output voltage value of the fuel cell due to the decrease of ruthenium in the platinum-ruthenium alloy catalyst is enlarged and read. Therefore, it is possible to obtain the ruthenium residual rate very accurately.

  Therefore, according to the principle shown in FIG. 2, by supplying a reformed gas containing carbon monoxide with a CO concentration C2 exceeding the CO concentration C1, which is an allowable concentration during normal power generation operation, to the fuel cell, a platinum-ruthenium alloy A minute decrease in ruthenium in the catalyst can also be obtained very accurately based on the decrease in the output voltage value of the fuel cell.

  For example, ruthenium is eluted by power generation operation or DSS operation over a long period of time, and the residual ratio of ruthenium in the platinum-ruthenium alloy catalyst is reduced from 100% (curve a) to 80% to 20% (curve b to curve e). In this case, even if the output voltage value of the fuel cell obtained by supplying the reformed gas containing carbon monoxide with CO concentration C1 is very small, the reformed gas containing carbon monoxide with CO concentration C2 is used as fuel. By supplying to the battery, it is possible to enlarge and accurately read the decrease value of the output voltage value of the fuel cell, such as the voltage difference ΔEab2 to ΔEae2 between the voltage value Ea2 and the voltage values Eb2 to Ee2. This makes it possible to determine the minute reduction of ruthenium in the platinum-ruthenium alloy catalyst very accurately.

  On the other hand, after the ruthenium residual rate in the platinum-ruthenium alloy catalyst is accurately determined, an optimal increase in the amount of air bleed is accurately determined according to the ruthenium residual rate.

  FIG. 3 shows the difference between the output voltage value of the fuel cell and the reference voltage value stored in the control unit of the fuel cell system, the residual rate of ruthenium in the platinum-ruthenium alloy catalyst, and the optimum increase amount of the air bleed amount. It is a data table which shows mutual relationship. In FIG. 3, item A indicates the voltage difference between the output voltage value of the fuel cell and the reference voltage value. Item B shows the residual rate of ruthenium in the platinum-ruthenium alloy catalyst. Item C shows the optimum amount of increase in the air bleed amount.

  In the fuel cell system, when the control unit accurately measures the voltage difference of the output voltage value of the fuel cell with respect to the reference voltage value, based on the correlation shown in FIG. 3, the control unit in the platinum-ruthenium alloy catalyst corresponding to the voltage difference. Accurately determine the ruthenium residual rate. And a control part calculates | requires exactly the optimal increase amount of the air bleed amount corresponding to the residual rate of the ruthenium based further on the correlation shown in FIG. For example, as shown in FIG. 3, when the control unit measures a voltage difference of 0, 100% of ruthenium remains in the platinum-ruthenium alloy catalyst, so the air bleed increase is set to 0. On the other hand, when the control unit measures the voltage differences ΔEab2 to ΔEaf2, the ruthenium remaining rate is 80% to 0%, and thus the air bleed increase is set to Sab to Saf.

  Actually, for example, a relational expression between a voltage difference with respect to a predetermined reference voltage value of a fuel cell obtained by supplying a reformed gas containing carbon monoxide having a CO concentration of C2 and a residual ratio of ruthenium is prepared in advance. The remaining rate of ruthenium in the platinum-ruthenium alloy catalyst is accurately obtained by inputting the decrease value of the output voltage value of the fuel cell into this relational expression. In addition, a relational expression between the ruthenium residual rate and the air bleed amount increase in the platinum-ruthenium alloy catalyst is prepared in advance, and by inputting the ruthenium residual rate into this relational expression, the air bleed amount increasing amount Find exactly. These calculations are executed by a control unit included in the fuel cell system.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
First, the configuration of the fuel cell system 100 according to Embodiment 1 will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram schematically showing a part of the configuration of the fuel cell system shown in Embodiment 1 of the present invention. FIG. 1 shows a configuration of a fuel cell system that uses a reformed gas generated by reforming a city gas as a fuel gas and uses air as an oxidant gas.

  As shown in FIG. 1, the fuel cell system 100 of the present embodiment includes a raw material flow rate adjustment valve 1 and a desulfurizer 2. The raw material flow rate adjusting valve 1 adjusts the amount of city gas supplied from the city gas supply means to the desulfurizer 2. The desulfurizer 2 removes odorants such as mercaptan and dimethyl sulfide contained in the city gas that has passed through the raw material flow rate adjustment valve 1. The city gas infrastructure is used as the city gas supply means.

  The fuel cell system 100 includes a reformer 3, a transformer 4, and a purifier 5. The reformer 3 uses the city gas from which the odorant has been removed by passing through the desulfurizer 2 to generate a reformed gas rich in hydrogen by a steam reforming reaction. Further, the transformer 4 reduces the concentration of carbon monoxide contained in the reformed gas generated by the reformer 3 by a shift reaction. The purifier 5 further reduces the concentration of carbon monoxide contained in the reformed gas that has passed through the transformer 4 by a selective oxidation reaction. Each of the reformer 3, the transformer 4, and the purifier 5 is provided with a temperature sensor for detecting temperatures of a steam reforming reaction, a shift reaction, a selective oxidation reaction, and the like, which are not particularly illustrated in FIG. 1. ing.

  The fuel cell system 100 includes a combustor 6. The combustor 6 burns city gas or exhaust reformed gas discharged from the fuel cell 15 to be described later into the heat necessary for advancing the steam reforming reaction to at least the reformer 3. Supply. Note that flue gas generated by combustion in the combustor 6 is released to the outside of the fuel cell system 100.

  As shown in FIG. 1, in the fuel cell system 100 of the present embodiment, a fuel reforming section 7 is configured by at least the reformer 3, the transformer 4, the purifier 5, and the combustor 6. .

  The fuel cell system 100 includes a reforming water supply pump 8, a combustion city gas supply valve 9, a combustion air supply valve 10, and a selective oxidation flow rate adjusting unit 11. The reforming water supply pump 8 supplies water necessary for advancing the steam reforming reaction from the water supply means to the reformer 3 of the fuel reforming unit 7. In addition, as a means for supplying water, water is usually used. Moreover, the city gas supply valve 9 for combustion and the air supply valve 10 for combustion adjust the inflow of the city gas and air from the atmosphere to the combustor 6 with the city gas supply means. Further, the selective oxidation flow rate adjusting unit 11 adjusts the amount of air necessary to advance the selective oxidation reaction from the air flow rate adjusting unit 17 (described later) to the purifier 5 of the fuel reforming unit 7.

  The fuel cell system 100 includes a fuel cell 15 as a main body of the power generation unit. The fuel cell 15 generates power using the reformed gas generated by the fuel reforming unit 7. The fuel cell system 100 according to the present embodiment includes a polymer electrolyte fuel cell that can generate power at a relatively low temperature as the fuel cell 15. Here, the polymer electrolyte fuel cell includes a polymer electrolyte membrane having proton conductivity. The polymer electrolyte membrane includes an anode catalyst and a cathode catalyst on both sides. In the present embodiment, a platinum-ruthenium alloy catalyst is used as at least the anode catalyst among these anode catalyst and cathode catalyst. By using this platinum-ruthenium alloy catalyst as at least an anode catalyst, ruthenium having an oxygen adsorption ability adsorbs oxygen from moisture or the like in the reformed gas supplied by the fuel reforming unit 7 during the power generation operation, and is thus deposited on the platinum. Since it is supplied, carbon monoxide bonded to platinum can be converted into carbon dioxide and released to the outside of the fuel cell 15. That is, with the configuration using this platinum-ruthenium alloy catalyst, the fuel cell system 100 imparts CO poisoning resistance to the fuel cell 15 itself.

  In the present embodiment, a configuration in which a platinum-ruthenium alloy catalyst is used as at least the anode catalyst is shown, but the present invention is not limited to a configuration in which this platinum-ruthenium alloy catalyst is used. For example, a transition metal such as rhodium may be used instead of ruthenium, and a platinum-rhodium alloy catalyst or the like may be used as at least the anode catalyst. Moreover, it is not limited to the structure using a transition metal with platinum, and any element can be used as long as it can suppress poisoning of the anode catalyst by adsorbing oxygen or the like and supplying it onto platinum. Even elements can be used together with platinum as part of the anode catalyst.

  In such a polymer electrolyte type fuel cell 15, a catalytic reaction in which hydrogen contained in the reformed gas is converted into protons and electrons proceeds on the anode catalyst by the catalytic action of platinum. At this time, protons move inside the polymer electrolyte membrane and reach the cathode catalyst. Further, the electrons reach the cathode catalyst via an external load that is electrically connected to the fuel cell system 100. On the other hand, on the cathode catalyst, a catalytic reaction of generating water from the protons and electrons that arrive and oxygen supplied from the humidifier 18 described later proceeds due to the catalytic action of platinum.

  The fuel cell system 100 includes a heat exchange unit 16. The heat exchanging unit 16 exchanges heat between the fuel cell 15 that generates heat during the power generation operation and the cooling water by circulating cooling water in a water storage tank (not particularly shown in FIG. 1) inside the fuel cell 15. Do. The heat exchanging unit 16 appropriately controls the operating temperature of the fuel cell 15 so that the temperature of the fuel cell 15 that generates heat during the power generation operation changes within a predetermined temperature range.

  The fuel cell system 100 includes a bypass valve 13 and a bypass path 14. The bypass valve 13 supplies the reformed gas generated by the fuel reforming unit 7 to the fuel cell 15 and the reformed gas generated by the fuel reforming unit 7 to the bypass path 14 as necessary. Switch as appropriate. Further, the bypass path 14 directly supplies the reformed gas generated by the fuel reforming unit 7 and passing through the bypass valve 13 to the condenser 19 described later, bypassing the fuel cell 15. For example, a three-way valve is used as the bypass valve 13.

  The fuel cell system 100 also includes an air flow rate adjustment unit 17. The air flow rate adjustment unit 17 adjusts the supply amount of air from the atmosphere to the selective oxidation flow rate adjustment unit 11, the humidifier 18 described later, and the air bleed mechanism 12 described later. In the fuel cell system 100 of the present embodiment, the air flow rate adjustment unit 17 receives supply of air from an air supply system that supplies air to the combustion air supply valve 10.

  The fuel cell system 100 includes a humidifier 18. The humidifier 18 heats and humidifies the air that has passed through the air flow rate adjustment unit 17 using the high-temperature, high-humidity exhaust air that is discharged from the fuel cell 15. In the present embodiment, a polymer electrolyte membrane 18 c similar to the polymer electrolyte membrane used in the fuel cell 15 is provided between the air channel 18 a and the exhaust air channel 18 b in the humidifier 18. The heat and moisture of the exhaust air discharged from the fuel cell 15 in the exhaust air flow path 18b via the polymer electrolyte membrane 18c are converted into the air that has passed through the air flow rate adjusting unit 17 in the air flow path 18a. Moving. The exhaust air that has passed through the exhaust air flow path 18 b of the humidifier 18 after being discharged from the fuel cell 15 is released to the outside of the fuel cell system 100.

  The fuel cell system 100 includes a condenser 19. The condenser 19 removes moisture contained in the exhaust reformed gas discharged from the fuel cell 15 by condensation during the power generation operation. The condenser 19 supplies the exhaust reformed gas from which unnecessary moisture has been removed to the combustor 6 of the fuel reforming unit 7. The water removed from the exhaust reformed gas in the condenser 19 is discharged to the outside of the fuel cell system 100.

  The fuel cell system 100 includes an air bleed mechanism 12. The air bleed mechanism 12 supplies the air that has passed through the air flow rate adjusting unit 17 to the reformed gas generated by the fuel reforming unit 7 during the power generation operation before supplying the fuel cell 15 with a predetermined supply amount. By this air bleed mechanism 12, the fuel cell system 100 suppresses poisoning of the anode catalyst in the fuel cell 15.

  Specifically, the reformed gas generated by the fuel reforming unit 7 usually contains a small amount of carbon monoxide. This carbon monoxide is easily combined with platinum constituting the anode catalyst. That is, carbon monoxide contained in the reformed gas easily causes poisoning of the anode catalyst of the fuel cell 15. This poisoning of the anode catalyst significantly hinders the progress of the catalytic reaction that converts hydrogen on the anode catalyst into protons and electrons. Therefore, by supplying air to the reformed gas using the air bleed mechanism 12, oxygen is supplied onto the anode catalyst constituting the fuel cell 15 together with the reformed gas. And the carbon monoxide couple | bonded with an anode catalyst is further oxidized with the oxygen which the air bleed mechanism 12 supplies, and it converts into a carbon dioxide. As a result, the generated carbon dioxide is desorbed from the anode catalyst and discharged together with the exhaust reformed gas to the outside of the fuel cell 15, so that poisoning of the anode catalyst in the fuel cell 15 can be suppressed.

  That is, the fuel cell system 100 of the present embodiment basically uses the oxygen supply function on the anode catalyst of the air bleed mechanism 12 and converts the platinum of the platinum-ruthenium alloy catalyst in the fuel cell 15 to platinum. By further utilizing this oxygen supply function, poisoning of the anode catalyst of the fuel cell 15 is effectively suppressed, and deterioration of the power generation performance of the fuel cell 15 is effectively suppressed.

  The fuel cell system 100 includes a control unit 101. The control unit 101 appropriately controls the operation of each component constituting the fuel cell system 100 such as the fuel reforming unit 7, the air bleed mechanism 12, and the fuel cell 15 according to a control program stored in advance by the storage unit of the control unit 101. Control. Further, the control unit 101 measures the output voltage value of the fuel cell 15, and accurately grasps the ruthenium residual rate in the platinum-ruthenium alloy catalyst of the fuel cell 15 based on the measured output voltage value. And the control part 101 sets the supply_amount | feed_rate of the air to the reformed gas by the air bleed mechanism 12 in the power generation operation according to the ruthenium residual rate in the platinum-ruthenium alloy catalyst to an optimum supply amount.

  Next, the operation of the fuel cell system 100 of Embodiment 1 will be described in detail with reference to the drawings. In the present embodiment, the operation of each component constituting the fuel cell system 100 is appropriately controlled by the control unit 101.

  FIG. 4 is a flowchart schematically showing an operation during start-up operation of the fuel cell system shown in Embodiment 1 of the present invention. In FIG. 4, step S <b> 3 indicates a diagnostic step in which an accurate increase amount of the air bleed amount is determined based on the output voltage value of the fuel cell during start-up operation.

  During the start-up operation of the fuel cell system 100 shown in FIG. 1, the control unit 101 first opens both the combustion city gas supply valve 9 and the combustion air supply valve 10. Then, city gas and air are supplied to the combustor 6 from the city gas supply means and the atmosphere. On the other hand, when supplied with city gas and air, the combustor 6 mixes the city gas and air, and burns the mixed city gas and air mixture. Then, heating of the fuel reforming unit 7 is started by the combustion of the mixed gas in the combustor 6 (step S1).

  Next, in a state where the purifier 5 and the condenser 19 of the fuel reforming unit 7 are connected via the bypass valve 13 and the bypass path 14, the control unit 101 operates the raw material flow rate adjustment valve 1 to control the city gas. City gas is supplied from the supply means to the desulfurizer 2 at a predetermined flow rate. Then, the desulfurizer 2 removes the odorant such as mercaptan and dimethyl sulfide contained in the city gas, and then supplies the city gas from which the odorant has been removed to the reformer 3. At this time, the control unit 101 operates the reforming water supply pump 8 and starts supplying water from the water supply means to the reformer 3.

  While the combustor 6 starts to heat the fuel reforming unit 7, the desulfurizer 2 and the reformed water supply pump 8 each start supplying city gas and water to the reformer 3 with predetermined supply amounts, When the air flow rate adjusting unit 17 and the selective oxidation flow rate adjusting unit 11 start supplying air to the purifier 5 at a predetermined supply amount, the reformer 3, the transformer 4, and the purifier 5 in the fuel reforming unit 7 are Then, generation of reformed gas containing hydrogen is started by the steam reforming reaction, the shift reaction, and the selective oxidation reaction (step S2).

  At this time, until the temperature of the reformer 3 in the fuel reforming unit 7 reaches a predetermined temperature for causing the steam reforming reaction to proceed, the reformed gas generated by the fuel reforming unit 7 has a very high concentration. Of carbon monoxide. Therefore, in the fuel cell system 100, the reformed gas containing this very high concentration of carbon monoxide is supplied to the condenser 19 via the bypass valve 13 and the bypass path 14.

  Thereafter, the diagnostic step S3 (step SS1 to step SS6) for accurately determining the optimum increase amount of the air bleed amount on the basis of the output voltage value of the fuel cell 15 at the start-up operation proceeds.

  The control unit 101 sequentially monitors changes in the temperature Ts of the transformer 4 in the fuel reforming unit 7 using a temperature sensor. On the other hand, the temperature Ts of the transformer 4 is gradually or directly heated by heat generated by the combustor 6 by burning the mixed gas, heat of the reformed gas discharged from the reformer 3, or the like. To rise. Then, the control unit 101 determines whether or not the temperature Ts of the transformer 4 has reached a diagnostic temperature Td (for example, 140 ° C.) that is lower than a predetermined temperature (for example, 200 ° C.) for causing the shift reaction to proceed. Is determined (step SS1).

  When the control unit 101 determines that the temperature Ts of the transformer 4 has reached the diagnostic temperature Td (YES in step SS1), the state of the bypass valve 13 is changed between the purifier 5 of the fuel reforming unit 7 and the fuel cell 15. The state where the connection is cut off and the purifier 5 and the condenser 19 are connected is changed to the state where the purifier 5 and the fuel cell 15 are connected and the connection between the purifier 5 and the condenser 19 is cut off. As a result, the fuel reforming unit 7 converts the reformed gas containing carbon monoxide at a concentration (for example, 100 ppm) corresponding to the concentration C2 shown in FIG. 2 when the temperature Ts of the transformer 4 is the diagnostic temperature Td. Then, supply from the purifier 5 to the fuel cell 15 at a predetermined supply amount is started. At this time, the control unit 101 controls the air flow rate adjusting unit 17. Thereby, the humidifier 18 starts to supply air to the fuel cell 15 at a predetermined supply amount. And the control part 101 starts the diagnostic operation of the fuel cell 15 in order to obtain | require the residual rate of the ruthenium in a platinum-ruthenium alloy catalyst (step SS2).

  If the control unit 101 determines that the temperature Ts of the transformer 4 has not yet reached the diagnostic temperature Td (NO in step SS1), the control unit 101 continues to monitor the change of the temperature Ts of the transformer 4 using the temperature sensor. Then, the control unit 101 repeatedly determines whether or not the temperature Ts of the transformer 4 has reached the diagnostic temperature Td.

  Next, the control unit 101 measures the output voltage value Vd of the fuel cell 15 during the diagnostic operation. (Step SS3). At this time, the control unit 101 stores the value (for example, 740 mV) of the output voltage value Vd of the fuel cell 15 in a memory included in the control unit 101.

  Next, the control unit 101 interrupts the electrical connection between the fuel cell 15 and a load such as an inverter connected to the power output terminal of the fuel cell 15 and stops the power generation operation of the fuel cell 15. Further, the control unit 101 changes the state of the bypass valve 13 from the state where the purifier 5 of the fuel reforming unit 7 and the fuel cell 15 are connected and the connection between the purifier 5 and the condenser 19 is disconnected. 5 and the fuel cell 15 are disconnected, and the purifier 5 and the condenser 19 are connected. Thereby, the supply of the reformed gas from the fuel reforming unit 7 to the fuel cell 15 is stopped. At this time, the control unit 101 controls the operation of the air flow rate adjusting unit 17. Thereby, the humidifier 18 stops the supply of air to the fuel cell 15. And the control part 101 complete | finishes the diagnostic driving | operation of the fuel cell 15 (step SS4).

  Next, the control unit 101 compares the output voltage value Vd of the fuel cell 15 measured and stored in step SS3 with the reference voltage value Vs stored in advance in the memory of the control unit 101. Then, the control unit 101 determines whether or not the output voltage value Vd is lower than the reference voltage value Vs (step SS5).

  When the control unit 101 determines that the output voltage value Vd (eg, 740 mV) of the fuel cell 15 is lower than the reference voltage value Vs (eg, 750 mV) (YES in step SS5), the reference voltage value Vs and the output voltage value Vd. And the residual ratio of ruthenium in the platinum-ruthenium alloy catalyst is accurately obtained based on the voltage difference ΔV. Further, the optimum increase amount Sb (for example, 5% as the increase rate) of the air bleed amount to the fuel cell 15 is accurately obtained based on the ruthenium residual rate. Then, the control unit 101 sets the accurate increase amount Sb of the air bleed amount as the increase amount of the air bleed amount of the air bleed mechanism 12 (step SS6), and then ends the diagnostic step S3.

  In the present embodiment, the reference voltage value Vs is obtained when the ruthenium remaining rate in the platinum-ruthenium alloy catalyst is 100% and the concentration of carbon monoxide contained in the reformed gas is the CO concentration C2. The voltage value Ea2 shown in FIG.

  In step SS6, an arbitrary fixed value can be used as the reference voltage value Vs. Further, the reference voltage value is sequentially decreased as the output voltage value of the fuel cell 15 is lowered in advance due to deterioration of the components other than the anode catalyst, and with the elapsed time of the power generation operation of the fuel cell system 100. It is also possible. Further, in the DSS operation of the fuel cell system 100, the output voltage value of the fuel cell 15 at the end of the power generation operation on the previous day can be set as the reference voltage value.

  In step SS6, the accurate increase amount Sb of the air bleed amount is the default value of the increase amount of the air bleed amount with respect to the ruthenium residual rate, or the ruthenium residual rate and the air bleed amount, which the control unit 101 has in advance. It can be determined as appropriate based on the relational expression with the amount of increase. Here, the power generation operation time of the fuel cell system 100 may be introduced as a parameter in the relational expression between the ruthenium residual rate and the increase in the air bleed amount.

  On the other hand, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS5), the control unit 101 derives an accurate increase amount Sb of the ruthenium remaining rate and the air bleed amount. And the diagnostic step S3 is terminated without setting.

  Next, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is lower than the reference voltage value Vs (YES in step SS5), the control unit 101 determines the amount of air bleed to the fuel cell 15 by the air bleed mechanism 12. Increase by a predetermined amount. Specifically, the control unit 101 controls the air bleed mechanism 12 after the diagnostic step S3, and described above for the air bleed amount Sn when the residual ratio of ruthenium in the platinum-ruthenium alloy catalyst is 100%, for example. The increase amount Sb is added, and the supply of air to the reformed gas is started with the supply amount of the air bleed amount Sn + Sb (step S4a).

  On the other hand, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (in the case of NO in step SS5), after the diagnosis step S3, the air bleed amount Sn is increased. Supplying air to the reformed gas is started while maintaining the air bleed amount Sn without adding Sb (step S4b).

  Thereafter, the control unit 101 sequentially monitors the change in the temperature Ts of the transformer 4 in the fuel reforming unit 7 using a temperature sensor, and the temperature Ts of the transformer 4 causes a predetermined temperature Tpd (for example, advancing the shift reaction). , 200 ° C.), it is determined whether or not the temperature Ts of the transformer 4 is stabilized at the predetermined temperature Tpd (step S5).

  When the control unit 101 determines that the temperature Ts of the transformer 4 has reached the predetermined temperature Tpd for causing the shift reaction to proceed and is stable (YES in step S5), the state of the bypass valve 13 is changed to the fuel reforming unit. From the state where the connection between the purifier 5 and the fuel cell 15 is cut off and the purifier 5 and the condenser 19 are connected, the purifier 5 and the fuel cell 15 are connected and the purifier 5 and the condenser 19 are connected. Change to a state that blocks the connection. As a result, the fuel reforming unit 7 starts supplying the reformed gas to the fuel cell 15 at a predetermined supply amount. At this time, the control unit 101 controls the air flow rate adjusting unit 17 again. As a result, the humidifier 18 starts supplying air to the fuel cell 15 at a predetermined supply amount. At this time, the control unit 101 electrically connects the fuel cell 15 and a load such as an inverter connected to the power output terminal of the fuel cell 15 and starts the power generation operation of the fuel cell 15. Then, the control unit 101 starts the normal power generation operation of the fuel cell system 100 (step S6).

  On the other hand, when the control unit 101 determines that the temperature Ts of the transformer 4 has not reached the predetermined temperature Tpd for causing the shift reaction to proceed (NO in step S5), the control unit 101 determines the change in the temperature Ts of the transformer 4 as the temperature. Continue to monitor with sensors. Then, the control unit 101 repeatedly determines whether or not the temperature Ts of the transformer 4 has reached a predetermined temperature Tpd and is stable.

  After step S6 in FIG. 4, in the fuel cell system 100, the reformer 3 of the fuel reforming unit 7 continues to generate reformed gas by the steam reforming reaction. Further, the transformer 4 reduces the concentration of carbon monoxide contained in the reformed gas to about several percent by a shift reaction. Further, the purifier 5 reduces the concentration of carbon monoxide contained in the reformed gas to 50 ppm or less (preferably 20 ppm or less) by a selective oxidation reaction using air supplied by the selective oxidation flow rate adjusting unit 11. . That is, the fuel reforming unit 7 supplies the high-quality reformed gas in which the concentration of carbon monoxide is sufficiently reduced to the fuel cell 15 via the bypass valve 13. Further, the air bleed mechanism 12 continues the supply of air to the reformed gas generated by the fuel reformer 7 as shown in step S4a of FIG. 4 described above.

  The air flow rate adjustment unit 17 adjusts the amount of air supplied from the atmosphere to the selective oxidation flow rate adjustment unit 11, the humidifier 18, and the air bleed mechanism 12 after starting normal power generation operation. Then, the humidifier 18 heats and humidifies the air that has passed through the air flow rate adjusting unit 17 using high-temperature and high-humidity exhaust air that is discharged from the fuel cell 15, and then supplies the air to the fuel cell 15.

  In addition, the fuel cell 15 performs normal power generation using the reformed gas generated by the fuel reforming unit 7, the air supplied by the air bleed mechanism 12, and the heated and humidified air supplied by the humidifier 18. Continue driving. Thereby, the fuel cell system 100 continues the output of electric power.

  In the normal power generation operation, exhaust air discharged from the fuel cell 15 is used for heating and humidifying the air supplied by the air flow rate adjusting unit 17 in the humidifier 18 and then the fuel cell system 100. Released to the outside. The exhaust reformed gas discharged from the fuel cell 15 is supplied to the combustor 6 after unnecessary moisture is dehumidified in the condenser 19. Then, the combustor 6 is reused as fuel for heating at least the reformer 3 of the fuel reforming unit 7. At this time, when the temperature of the reformer 3 can be maintained only by the exhaust reformed gas discharged from the fuel cell 15, the control unit 101 closes the combustion city gas supply valve 9 and closes the combustor 6. Stop supplying city gas to the city. The heat generated in the fuel cell 15 is effectively utilized as a heat source for hot water supply by heat exchange with the cooling water in the heat exchange unit 16.

  On the other hand, when stopping the normal power generation operation of the fuel cell system 100, the control unit 101 cuts off the electrical connection with a load such as an inverter connected to the power output terminal of the fuel cell 15, so that the fuel cell 15 The normal power generation operation is stopped. Further, the control unit 101 changes the state of the bypass valve 13 from the state where the purifier 5 of the fuel reforming unit 7 and the fuel cell 15 are connected and the connection between the purifier 5 and the condenser 19 is disconnected. 5 and the fuel cell 15 are disconnected, and the purifier 5 and the condenser 19 are connected. Thereby, the control unit 101 stops the supply of the reformed gas from the fuel reforming unit 7 to the fuel cell 15. In addition, the control unit 101 stops the supply of air from the humidifier 18 to the fuel cell 15 by controlling the operation of the air flow rate adjusting unit 17.

  At this time, the control unit 101 operates the raw material flow rate adjustment valve 1 and the reforming water supply pump 8 to stop the supply of the city gas from the city gas supply means to the desulfurizer 2 and The supply of water from the supply means to the reformer 3 is stopped. Further, the control unit 101 closes the combustion city gas supply valve 9 and supplies the air that passes through the combustion air supply valve 10 to the fuel reforming unit 7. Reduce. Thereby, the control unit 101 stops the progress of the steam reforming reaction, the shift reaction, and the selective oxidation reaction that proceed in the reformer 3, the transformer 4, and the purifier 5. Then, the fuel reforming unit 7 stops the generation of the reformed gas.

  In addition, after the heat exchanging unit 16 cools the fuel cell 15 to a predetermined temperature, the control unit 101 stops all the operations of the respective components constituting the fuel cell system 100 to operate the fuel cell system 100. Stop completely.

  As described above, in the fuel cell system 100 shown in the present embodiment, during the start-up operation of the fuel cell system 100, the temperature Ts of the transformer 4 has reached the diagnostic temperature Td before reaching the predetermined temperature for the shift reaction. At that time, a reformed gas containing carbon monoxide at a high concentration temporarily is supplied from the fuel reformer 7 to the fuel cell 15. As a result, the voltage difference between the output voltage value Vd of the fuel cell 15 and the reference voltage value Vs can be detected very accurately, so that the residual rate of ruthenium in the platinum-ruthenium alloy catalyst of the fuel cell 15 can be determined very accurately. It becomes possible. And since the ruthenium residual rate in a platinum-ruthenium alloy catalyst can be calculated | required very correctly, it becomes possible to increase the air bleed amount to the reformed gas which the fuel reforming part 7 produces | generates very accurately.

  In addition, since the amount of air bleed to the reformed gas generated by the fuel reforming unit 7 can be increased extremely accurately, the apparent durability of the fuel cell 15 is thereby improved, so that the fuel cell It can also be expected to extend the life of the system 100.

  In addition, since the amount of air bleed into the reformed gas generated by the fuel reforming unit 7 can be increased extremely accurately, excess oxygen causes a simple combustion reaction of hydrogen contained in the reformed gas in the fuel cell 15. It becomes possible to suppress promotion. Accordingly, a necessary and sufficient amount of hydrogen can be ensured in the power generation operation of the fuel cell 15, so that the power generation efficiency of the fuel cell system 100 can be suitably ensured.

  In addition, according to the fuel cell system 100 shown in the present embodiment, the fuel reforming unit 7 is generated according to the residual rate of ruthenium in the platinum-ruthenium alloy catalyst of the fuel cell 15 during the start-up operation of the fuel cell system 100. Since the amount of air bleed into the reformed gas is increased very accurately, the output voltage value of the fuel cell 15 does not fluctuate during normal power generation operation. Therefore, it is possible to ensure a stable operation of the external load connected to the fuel cell system 100. In addition, it is possible to suppress variations in the output voltage value of each fuel cell (cell) constituting the fuel cell 15.

  Further, for example, in the DSS operation in which the normal power generation operation is stopped at night when the power consumption is reduced, the time point at which the temperature Ts of the transformer 4 becomes equal to the diagnostic temperature Td inevitably exists every time when the fuel cell system 100 is started. Therefore, it is possible to easily obtain a reformed gas that temporarily contains carbon monoxide at a high concentration without performing a special operation during the start-up operation. Accordingly, since the ruthenium remaining rate in the platinum-ruthenium alloy catalyst of the fuel cell 15 can be easily and accurately obtained, the amount of air bleed into the reformed gas generated by the fuel reforming section 7 can be easily and accurately determined. It becomes possible to increase.

  Further, the operation of the fuel cell system 100 shown in the present embodiment can be performed in the configuration of the conventional fuel cell system without preparing any special components. Therefore, it is possible to easily obtain the ruthenium remaining rate in the platinum-ruthenium alloy catalyst of the fuel cell 15 and easily increase the amount of air bleed to the reformed gas generated by the fuel reforming unit 7.

  That is, according to the fuel cell system 100 shown in the present embodiment, it is possible to accurately grasp the performance deterioration of the anode catalyst of the fuel cell 15 with a simple configuration and accurately increase the amount of air bleed. It is possible to provide a suitable fuel cell system 100 having excellent durability, power generation efficiency, and stability of the output voltage value during normal power generation operation.

  In the present embodiment, during the start-up operation of the fuel cell system 100, when the temperature Ts of the transformer 4 in the fuel reforming unit 7 reaches a predetermined diagnostic temperature Td, the carbon monoxide is temporarily made high in concentration. Although the structure which supplies the reformed gas containing to the fuel cell 15 was demonstrated, it is not limited to such a structure. For example, during the start-up operation of the fuel cell system 100, the CO sensor sequentially monitors the concentration of carbon monoxide contained in the reformed gas generated by the fuel reforming unit 7, and the concentration of this carbon monoxide is a predetermined diagnostic concentration. Alternatively, the reformed gas that temporarily contains carbon monoxide at a high concentration may be supplied to the fuel cell 15. That is, any configuration may be used as long as it can supply the reformed gas containing carbon monoxide at a high concentration temporarily to the fuel cell 15 during the start-up operation of the fuel cell system 100. Even with such a configuration, it is possible to obtain the same effects as those obtained in the present embodiment.

  In the present embodiment, during the start-up operation of the fuel cell system 100, the output voltage value Vd of the fuel cell 15 when the reformed gas that temporarily contains carbon monoxide at a high concentration is supplied is measured. Based on the voltage difference ΔV between the output voltage value Vd and the reference voltage value Vs, the residual rate of ruthenium in the platinum-ruthenium alloy catalyst is accurately obtained, and the optimal amount of increase in the air bleed amount is determined based on the residual rate of ruthenium. Although the configuration to be accurately obtained has been described, the configuration is not limited to such a configuration. For example, after the start-up operation of the fuel cell system 100, after measuring the output voltage value Vd of the fuel cell 15 when supplying the reformed gas that temporarily contains carbon monoxide at a high concentration, the output voltage value Vd and the reference The voltage when supplying the reformed gas containing the allowable concentration of carbon monoxide (that is, equivalent to the CO concentration C1 shown in FIG. 2) based on a predetermined conversion table based on the voltage difference ΔV1 from the voltage value Vs. The difference is converted to ΔV2. And it is good also as a structure which calculates | requires correctly the residual rate of the ruthenium in a platinum-ruthenium alloy catalyst based on this voltage difference (DELTA) V2, and calculates | requires the optimal increase amount of an air bleed amount correctly based on this residual rate of ruthenium. Even with such a configuration, it is possible to obtain the same effects as those obtained in the present embodiment.

  In the present embodiment, during the start-up operation of the fuel cell system 100, the voltage obtained based on the voltage difference ΔV between the output voltage value Vd of the fuel cell 15 and the reference voltage value Vs or by converting the voltage difference ΔV1. Although the ruthenium residual rate in the platinum-ruthenium alloy catalyst is accurately obtained based on the difference ΔV2 and the optimum increase amount of the air bleed amount is accurately obtained based on the ruthenium residual rate, the configuration has been described. The configuration is not limited. For example, based on the voltage difference ΔV or on the basis of the voltage difference ΔV2 obtained by converting the voltage difference ΔV1, the optimum increase amount of the air bleed amount is obtained without obtaining the ruthenium residual rate in the platinum-ruthenium alloy catalyst. It is good also as composition which asks directly. That is, if the voltage difference ΔV, or the voltage difference ΔV1 or ΔV2, and the optimum increase amount of the air bleed correspond strictly, it is possible to obtain the same effect as that obtained in the present embodiment. is there.

  Further, the diagnostic temperature Td, the reference voltage value Vs, and the like shown in the present embodiment cannot be uniquely defined because their optimum values vary depending on the form of the fuel cell system 100, the usage application, and the like. In other words, the effects of the present invention can be obtained by setting optimum values such as the diagnostic temperature Td and the reference voltage value Vs according to the form of the fuel cell system 100 and the usage application.

  In the present embodiment, a configuration in which a polymer electrolyte fuel cell is provided as the fuel cell 15 has been described. However, the configuration is not limited to such a configuration. That is, the present invention can be applied to any fuel cell system as long as the gist of the present invention is applicable.

(Embodiment 2)
In the second embodiment according to the present invention, the control method for obtaining the reformed gas containing carbon monoxide for diagnostic operation is different from the control method in the first embodiment.

  Specifically, when determining whether or not to start the diagnostic operation of the fuel cell 15 during the start-up operation of the fuel cell system 100, the first embodiment is implemented instead of detecting the temperature Ts of the transformer. In form 2, the temperature Tp of the purifier is detected. Then, it is determined whether or not the temperature Tp of the purifier has reached a diagnostic temperature Td that is lower than a predetermined temperature Tpd for causing the selective oxidation reaction, and the temperature Tp of the purifier reaches the diagnostic temperature Td. Then, the reformed gas containing carbon monoxide for diagnostic operation generated by the fuel reforming unit 7 is supplied to the fuel cell 15. Then, the diagnostic operation of the fuel cell 15 is started. Further, after the temperature Tp of the purifier reaches a predetermined temperature Tpd for causing the selective oxidation reaction to proceed, the normal power generation operation of the fuel cell system 100 is started.

  In other respects, the configuration and operation of the fuel cell system 100 shown in the second embodiment are the same as the configuration and operation of the fuel cell system 100 shown in the first embodiment. Therefore, in the second embodiment, regarding the configuration and operation of the fuel cell system 100, the description of the same configuration and operation as those described in the first embodiment is omitted.

  Hereinafter, with respect to the operation of the fuel cell system 100 of the second embodiment, differences from the operation of the fuel cell system 100 shown in the first embodiment will be described in detail with reference to FIG.

  FIG. 5 is a flowchart schematically showing an operation during start-up operation of fuel cell system 100 shown in Embodiment 2 of the present invention. In FIG. 5, step S <b> 3 indicates a diagnostic step of determining an optimum increase amount of the air bleed amount based on the output voltage value of the fuel cell during the start-up operation.

  As shown in FIG. 5, in the fuel cell system 100 of the second embodiment, heating of the fuel reforming unit 7 is started (step S1), and generation of reformed gas is started in the fuel reforming unit 7 (step S1). S2), the diagnostic step S3 (step SS1 to step SS6) for determining the optimum increase amount of the air bleed amount on the basis of the output voltage value of the fuel cell 15 proceeds.

  The control unit 101 sequentially monitors changes in the temperature Tp of the purifier 5 in the fuel reforming unit 7 using a temperature sensor. On the other hand, the temperature Tp of the purifier 5 is directly or indirectly heated by heat generated by the combustor 6 burning the mixed gas, heat of the reformed gas discharged from the reformer 3 and the transformer 4, or the like. Being gradually raised. Then, has the controller 101 reached the diagnostic temperature Td (for example, 100 ° C.) that is lower than the predetermined temperature Tpd (for example, 150 ° C.) for allowing the selective oxidation reaction to proceed? It is determined whether or not (step SS1).

  When the control unit 101 determines that the temperature Tp of the purifier 5 has reached the diagnostic temperature Td (YES in step SS1), the fuel reforming unit 7 shows a diagram when the temperature Tp of the purifier 5 is the diagnostic temperature Td. The reformed gas containing carbon monoxide at a concentration (for example, 110 ppm) corresponding to the CO concentration C2 shown in 2 is started to be supplied from the purifier 5 to the fuel cell 15 at a predetermined supply amount. At this time, the control unit 101 controls the air flow rate adjusting unit 17. Thereby, the humidifier 18 starts to supply air to the fuel cell 15 at a predetermined supply amount. And the control part 101 starts the diagnostic driving | operation of the fuel cell 15 (step SS2).

  If the controller 101 determines that the temperature Tp of the purifier 5 has not yet reached the diagnostic temperature Td (NO in step SS1), the controller 101 continues to monitor the change in the temperature Tp of the purifier 5 using the temperature sensor. Then, the controller 101 repeatedly determines whether or not the temperature Tp of the purifier 5 has reached the diagnostic temperature Td.

  Next, after measuring the output voltage value Vd of the fuel cell 15 during the diagnostic operation (Step SS3), the control unit 101 ends the diagnostic operation of the fuel cell 15 (Step SS4).

  Next, the control unit 101 compares the output voltage value Vd of the fuel cell 15 measured and stored in step SS3 with the reference voltage value Vs, and determines whether or not the output voltage value Vd is lower than the reference voltage value Vs. (Step SS5).

  When the control unit 101 determines that the output voltage value Vd (eg, 740 mV) of the fuel cell 15 is lower than the reference voltage value Vs (eg, 750 mV) (YES in step SS5), the reference voltage value Vs and the output voltage value Vd. The ruthenium residual rate in the platinum-ruthenium alloy catalyst is accurately obtained based on the voltage difference ΔV with respect to the fuel cell 15, and then an accurate increase amount Sb (for example, 5% as the increase rate) of the air bleed amount to the fuel cell 15 is obtained. . Then, the control unit 101 sets the accurate increase amount Sb of the air bleed amount as the increase amount of the air bleed amount of the air bleed mechanism 12 (step SS6), and then ends the diagnostic step S3.

  If the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS5), the control unit 101 derives an accurate increase amount Sb of the ruthenium residual rate and the air bleed amount. And the diagnostic step S3 is terminated without setting.

  Next, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is lower than the reference voltage value Vs (YES in step SS5), the air bleed amount Sn + Sb is controlled by controlling the air bleed mechanism 12. The supply of air to the reformed gas is started at a supply amount of (step S4a). On the other hand, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS5), the control unit 101 maintains the air bleed amount Sn and returns to the reformed gas. The air supply is started (step S4b).

  Thereafter, the control unit 101 sequentially monitors the change in the temperature Tp of the purifier 5 in the fuel reforming unit 7 with a temperature sensor, while the temperature Tp of the purifier 5 proceeds to a predetermined temperature Tpd ( For example, it is determined whether or not the temperature Tp of the purifier 5 has been stabilized at the predetermined temperature Tpd (step S5).

  When control unit 101 determines that temperature Tp of purifier 5 has reached a predetermined temperature Tpd for allowing the selective oxidation reaction to proceed and is stable (YES in step S5), normal power generation operation of fuel cell system 100 is performed. Is started (step S6).

  When the control unit 101 determines that the temperature Tp of the purifier 5 has not reached the predetermined temperature Tpd for causing the selective oxidation reaction to proceed (NO in step S5), the control unit 101 changes the temperature Tp of the purifier 5. Continue to monitor with temperature sensor. Then, the control unit 101 repeatedly determines whether or not the temperature Tp of the purifier 5 has reached a predetermined temperature Tpd and has been stabilized.

  As described above, in the fuel cell system 100 shown in the present embodiment, during the start-up operation of the fuel cell system 100, the temperature Tp of the purifier 5 reaches the diagnosis temperature Td before reaching the predetermined temperature Tpd for the selective oxidation reaction. When the fuel gas reaches the fuel cell 15, the reformed gas that temporarily contains carbon monoxide at a high concentration is supplied from the fuel reformer 7 to the fuel cell 15. As a result, the voltage difference ΔV between the output voltage value Vd of the fuel cell 15 and the reference voltage value Vs is accurately detected, the ruthenium residual rate in the platinum-ruthenium alloy catalyst of the fuel cell 15 is accurately obtained, and the fuel is improved. The amount of air bleed into the reformed gas generated by the mass part 7 is accurately increased. Even with such a configuration, it is possible to obtain the same effect as in the first embodiment.

  Also in the present embodiment, there is necessarily a point in time every day when the temperature Tp of the purifier 5 becomes equal to the diagnostic temperature Td during the start-up operation of the fuel cell system 100. Therefore, a special operation is performed during the start-up operation. It is possible to easily obtain a reformed gas that temporarily contains carbon monoxide at a high concentration without being performed and without preparing special components.

  Other points are the same as those in the first embodiment.

(Embodiment 3)
In the third embodiment according to the present invention, the control method for obtaining the reformed gas containing carbon monoxide for diagnostic operation is different from the control method in the first and second embodiments.

  Specifically, in the first and second embodiments, when the diagnostic operation of the fuel cell 15 is started, the temperature Ts of the transformer 4 or the temperature Tp of the purifier 5 is a predetermined value for causing the shift reaction or the selective oxidation reaction to proceed. When the temperature reaches a diagnostic temperature Td, which is lower than the temperature Tpd, the reformed gas containing carbon monoxide for diagnostic operation generated by the fuel reforming unit 7 is supplied to the fuel cell 15. Instead, in the fuel cell system 100 of the third embodiment, the temperature Tfr of the fuel reforming unit 7 (that is, the temperature Tsr of the reformer 3, the temperature Ts of the transformer 4, and the temperature Tp of the purifier 5) is set. After reaching the predetermined temperature Tpd, the supply amount of air to the purifier 5 is reduced or stopped to obtain a reformed gas containing carbon monoxide for diagnostic operation. Then, the reformed gas containing carbon monoxide for diagnostic operation generated by the fuel reforming unit 7 is supplied to the fuel cell 15 and the diagnostic operation of the fuel cell 15 is started. In addition, after canceling the decrease or stop of the supply of air to the purifier 5, the normal power generation operation of the fuel cell system 100 is started.

  In other respects, the configuration and operation of the fuel cell system 100 shown in the third embodiment are the same as the configuration and operation of the fuel cell system 100 shown in the first and second embodiments. Therefore, in the third embodiment, regarding the configuration and operation of the fuel cell system 100, the description of the same configuration and operation as those described in the first and second embodiments is omitted.

  Hereinafter, with respect to the operation of the fuel cell system 100 of the third embodiment, differences from the operation of the fuel cell system 100 shown in the first and second embodiments will be described in detail with reference to FIG.

  FIG. 6 is a flowchart schematically showing an operation during start-up operation of fuel cell system 100 shown in Embodiment 3 of the present invention. In FIG. 6, step S <b> 3 indicates a diagnostic step for determining an optimum increase amount of the air bleed amount based on the output voltage value Vd of the fuel cell 15 during the start-up operation.

  As shown in FIG. 6, in the fuel cell system 100 of Embodiment 3, heating of the fuel reforming unit 7 is started (step S1), and generation of reformed gas is started in the fuel reforming unit 7 (step S1). S2), the diagnostic step S3 (step SS1 to step SS8) for determining the optimum increase amount of the air bleed amount on the basis of the output voltage value Vd of the fuel cell 15 proceeds.

  The control unit 101 sequentially monitors changes in the temperature Tsr of the reformer 3, the temperature Ts of the transformer 4, and the temperature Tp of the purifier 5 in the fuel reforming unit 7 using temperature sensors. On the other hand, the temperature Tsr of the reformer 3, the temperature Ts of the transformer 4 and the temperature Tp of the purifier 5 are the heat generated by the combustor 6 burning the mixed gas, and the reformer 3 and the transformer 4 are discharged. It is heated directly or indirectly by the heat of the reformed gas to rise and gradually rises. Then, the control unit 101 determines whether or not the temperature Tsr of the reformer 3 has reached a predetermined temperature Tpd (for example, 650 ° C.) for causing the steam reforming reaction to proceed, and the temperature Ts of the transformer 4 is It is determined whether or not a predetermined temperature Tpd (for example, 200 ° C.) for proceeding with the shift reaction has been reached, and the predetermined temperature Tpd (for example, 150 ° C.) for allowing the temperature Tp of the purifier 5 to proceed with the selective oxidation reaction. ) Is determined. That is, the control unit 101 determines whether or not the temperature Tfr of the fuel reforming unit 7 has reached a predetermined temperature Tpd (step SS1).

  If the control unit 101 determines that the temperature Tfr of the fuel reforming unit 7 has reached the predetermined temperature Tpd (YES in step SS1), the control unit 101 controls the selective oxidation flow rate adjustment unit 11 to purify from the air flow rate adjustment unit 17. The amount of air supplied to the vessel 5 is decreased (step SS2). Alternatively, when the control unit 101 determines that the temperature Tfr of the fuel reforming unit 7 has reached the predetermined temperature Tpd, the control unit 101 controls the selective oxidation flow rate adjustment unit 11 to transfer the air flow rate adjustment unit 17 to the purifier 5. Stop the air supply. By the control shown in step SS2, the concentration of carbon monoxide in the reformed gas generated by the fuel reforming unit 7 increases.

  Next, the fuel reforming unit 7 is shown in FIG. 2 after the amount of air supplied from the air flow rate adjusting unit 17 to the purifier 5 is reduced at a predetermined reduction rate (for example, 50% during normal power generation operation). The reformed gas containing carbon monoxide at a concentration (for example, 150 ppm) corresponding to the CO concentration C2 is started to be supplied from the purifier 5 to the fuel cell 15 at a predetermined supply amount. At this time, the control unit 101 controls the air flow rate adjusting unit 17. Thereby, the humidifier 18 starts to supply air to the fuel cell 15 at a predetermined supply amount. And the control part 101 starts the diagnostic driving | operation of the fuel cell 15 (step SS3).

  If the control unit 101 determines that the temperature Tfr of the fuel reforming unit 7 has not reached the predetermined temperature Tpd (NO in step SS1), the control unit 101 continues to change the temperature Tfr of the fuel reforming unit 7 using the temperature sensor. Monitor. Then, the control unit 101 repeatedly determines whether or not the temperature Tfr of the fuel reforming unit 7 has reached a predetermined temperature Tpd.

  Next, after measuring the output voltage value Vd of the fuel cell 15 during the diagnostic operation (Step SS4), the control unit 101 ends the diagnostic operation of the fuel cell 15 (Step SS5).

  Next, after the diagnostic operation of the fuel cell 15 is completed, the control unit 101 controls the selective oxidation flow rate adjusting unit 11 to return the amount of air supplied from the air flow rate adjusting unit 17 to the purifier 5 (step). SS6). Alternatively, after the diagnostic operation of the fuel cell 15 is completed, the control unit 101 controls the selective oxidation flow rate adjustment unit 11 to restore the stop of air supply from the air flow rate adjustment unit 17 to the purifier 5. By the control shown in step SS6, the concentration of carbon monoxide in the reformed gas generated by the fuel reforming unit 7 is restored.

  Next, the control unit 101 compares the output voltage value Vd of the fuel cell 15 measured and stored in step SS4 with the reference voltage value Vs, and determines whether or not the output voltage value Vd is lower than the reference voltage value Vs. (Step SS7).

  When the control unit 101 determines that the output voltage value Vd (for example, 725 mV) of the fuel cell 15 is lower than the reference voltage value Vs (for example, 730 mV) (YES in step SS7), the reference voltage value Vs and the output voltage value Vd. The ruthenium residual rate in the platinum-ruthenium alloy catalyst is accurately obtained based on the voltage difference ΔV with respect to the fuel cell 15, and then an accurate increase amount Sb (for example, 6% as the increase rate) of the air bleed amount to the fuel cell 15 is obtained. . Then, the control unit 101 sets the accurate increase amount Sb of the air bleed amount as the increase amount of the air bleed amount of the air bleed mechanism 12 (step SS8), and then ends the diagnostic step S3.

  If the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS7), the control unit 101 derives an accurate increase amount Sb of the ruthenium remaining rate and the air bleed amount. And the diagnostic step S3 is terminated without setting.

  Next, when the control unit 101 determines that the value of the output voltage value Vd of the fuel cell 15 is lower than the value of the reference voltage value Vs (in the case of YES in step SS7), by controlling the air bleed mechanism 12, Supply of air to the reformed gas is started with the supply amount of air bleed amount Sn + Sb (step S4a). On the other hand, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS7), the control unit 101 maintains the air bleed amount Sn and returns to the reformed gas. The air supply is started (step S4b).

  Then, the control unit 101 starts the normal power generation operation of the fuel cell system 100 after step S4a or step S4b (step S5).

  As described above, in the fuel cell system 100 shown in the present embodiment, during the start-up operation of the fuel cell system 100, after the temperature Tfr of the fuel reforming unit 7 reaches the predetermined temperature Tpd, the selective oxidation flow rate adjusting unit 11 is set. By controlling or reducing the supply amount of air to the purifier 5 in the fuel reforming unit 7 from the air flow rate adjusting unit 17 or stopping the supply, the reformed gas temporarily containing high concentration of carbon monoxide is fueled. The fuel is supplied from the reforming unit 7 to the fuel cell 15. As a result, the voltage difference ΔV between the output voltage value Vd of the fuel cell 15 and the reference voltage value Vs is accurately detected, the ruthenium residual rate in the platinum-ruthenium alloy catalyst of the fuel cell 15 is accurately obtained, and the fuel is improved. The amount of air bleed into the reformed gas generated by the mass part 7 is accurately increased. Even with this configuration, it is possible to obtain the same effects as those of the first and second embodiments.

  Further, according to the present embodiment, during the start-up operation of the fuel cell system 100, the selective oxidation flow rate adjusting unit 11 is controlled to supply air from the air flow rate adjusting unit 17 to the purifier 5 in the fuel reforming unit 7. It is very easy to reduce the volume or stop the supply, so that the carbon monoxide is temporarily increased without any special operation during the start-up operation and without any special components being prepared. The reformed gas included in the concentration can be easily obtained.

  Other points are the same as those in the first and second embodiments.

(Embodiment 4)
In the fourth embodiment according to the present invention, the control method for obtaining the reformed gas containing carbon monoxide for diagnostic operation is different from the control method in the first to third embodiments.

  That is, in the first to third embodiments, the diagnosis operation of the fuel cell 15 is performed during the start-up operation of the fuel cell system 100, whereas in the fourth embodiment, the diagnosis of the fuel cell 15 is performed during the stop operation of the fuel cell system 100. Do the driving.

  Specifically, in the fourth embodiment, when determining whether or not to start the diagnostic operation of the fuel cell 15 when the fuel cell system 100 is stopped, the transformer 4 is the same as in the first embodiment. The temperature Ts is detected. Then, it is determined whether or not the temperature Ts of the transformer 4 has decreased to a diagnostic temperature Td that is lower than a predetermined temperature Tpd for causing the shift reaction to proceed, and the temperature Ts of the transformer 4 becomes the diagnostic temperature Td. When the fuel gas is reduced to, the reformed gas containing carbon monoxide for diagnostic operation generated by the fuel reforming unit 7 is supplied to the fuel cell 15. Then, the diagnostic operation of the fuel cell 15 is started. In addition, after the temperature Tfr of the fuel reforming unit 7 has decreased to the predetermined temperature Tpd and the temperature of the fuel cell 15 has decreased to the predetermined temperature, the operation of the fuel cell system 100 is completely stopped.

  In other respects, the configuration and operation of the fuel cell system 100 shown in the fourth embodiment are the same as the configuration and operation of the fuel cell system 100 shown in the first to third embodiments. Therefore, in the fourth embodiment, regarding the configuration and operation of the fuel cell system 100, the description of the same configuration and operation as those described in the first to third embodiments is omitted.

  Hereinafter, with respect to the operation of the fuel cell system 100 of the fourth embodiment, differences from the operation of the fuel cell system 100 shown in the first to third embodiments will be described in detail with reference to FIG.

  FIG. 7 is a flowchart schematically showing an operation during stop operation of fuel cell system 100 shown in Embodiment 4 of the present invention. In FIG. 7, step S <b> 3 indicates a diagnostic step for determining an optimum increase amount of the air bleed amount based on the output voltage value Vd of the fuel cell 15 during the stop operation.

  When the fuel cell system 100 shown in FIG. 1 is stopped, the control unit 101 first cuts off the electrical connection between the fuel cell 15 and a load such as an inverter connected to the power output terminal of the fuel cell 15. Thus, the normal power generation operation of the fuel cell 15 is stopped (step S1).

  At this time, the control unit 101 purifies the state of the bypass valve 13 from the state where the purifier 5 and the fuel cell 15 of the fuel reforming unit 7 are connected and the connection between the purifier 5 and the condenser 19 is cut off. The connection between the purifier 5 and the fuel cell 15 is cut off and the purifier 5 and the condenser 19 are connected. Thereby, the supply of the reformed gas from the fuel reforming unit 7 to the fuel cell 15 is stopped. At this time, the control unit 101 controls the operation of the air flow rate adjusting unit 17. Thereby, the humidifier 18 stops the supply of air to the fuel cell 15.

  Next, the control unit 101 connects the raw material flow rate adjustment valve 1 and the reforming water supply pump 8 in a state where the purifier 5 and the condenser 19 of the fuel reforming unit 7 are connected via the bypass valve 13 and the bypass path 14. By controlling, the supply amount of city gas to the desulfurizer 2 and the supply amount of water to the reformer 3 are decreased. Or the control part 101 controls the city gas supply valve 9 for combustion in the state which connected the purifier 5 and the condenser 19 of the fuel reforming part 7 via the bypass valve 13 and the bypass path | route 14, and combustion The supply of city gas to the vessel 6 is stopped. At this time, the supply of air from the combustion air supply valve 10 to the combustor 6 is continued.

  By reducing the supply amount of city gas to the desulfurizer 2 and the supply amount of water to the reformer 3, or by stopping the supply of city gas to the combustor 6, the control unit 101 causes the fuel modification. Cooling of the mass part 7 is started (step S2).

  Thereafter, the diagnostic step S3 (step SS1 to step SS6) for determining the optimum increase amount Sb of the air bleed amount based on the output voltage value Vd of the fuel cell 15 during the stop operation of the fuel cell system 100 proceeds.

  The control unit 101 sequentially monitors changes in the temperature Ts of the transformer 4 in the fuel reforming unit 7 using a temperature sensor. On the other hand, the temperature Ts of the transformer 4 is directly decreased by decreasing the supply amount of city gas to the desulfurizer 2 and the supply amount of water to the reformer 3, or stopping the supply of city gas to the combustor 6. Or it cools indirectly and falls gradually. Then, has the controller 101 lowered the temperature Ts of the transformer 4 to a diagnostic temperature Td (eg, 130 ° C.) that is lower than a predetermined temperature Tpd (eg, 200 ° C.) for causing the shift reaction to proceed? It is determined whether or not (step SS1).

  When the control unit 101 determines that the temperature Ts of the transformer 4 has decreased to the diagnostic temperature Td (YES in step SS1), the fuel reforming unit 7 shows a diagram when the temperature Ts of the transformer 4 is the diagnostic temperature Td. The reformed gas containing carbon monoxide at a concentration (for example, 110 ppm) corresponding to the CO concentration C2 shown in 2 is started to be supplied from the purifier 5 to the fuel cell 15 at a predetermined supply amount. At this time, the control unit 101 controls the air flow rate adjusting unit 17. Thereby, the humidifier 18 starts to supply air to the fuel cell 15 at a predetermined supply amount. And the control part 101 starts the diagnostic driving | operation of the fuel cell 15 (step SS2).

  If the controller 101 determines that the temperature Ts of the transformer 4 has not yet decreased to the diagnostic temperature Td (NO in step SS1), the controller 101 continues to monitor the change of the temperature Ts of the transformer 4 using the temperature sensor. Then, the control unit 101 repeatedly determines whether or not the temperature Ts of the transformer 4 has decreased to the diagnostic temperature Td.

  Next, after measuring the output voltage value Vd of the fuel cell 15 during the diagnostic operation (Step SS3), the control unit 101 ends the diagnostic operation of the fuel cell 15 (Step SS4).

  Next, the control unit 101 compares the output voltage value Vd of the fuel cell 15 measured and stored in step SS3 with the reference voltage value Vs, and determines whether or not the output voltage value Vd is lower than the reference voltage value Vs. (Step SS5).

  In step SS5, as for the reference voltage value Vs, the output voltage value of the fuel cell 15 immediately before stopping the normal power generation operation of the fuel cell system 100 can be set as the reference voltage value Vs.

  When the control unit 101 determines that the output voltage value Vd (eg, 740 mV) of the fuel cell 15 is lower than the reference voltage value Vs (eg, 750 mV) (YES in step SS5), the reference voltage value Vs and the output voltage value Vd. The ruthenium residual rate in the platinum-ruthenium alloy catalyst is accurately obtained based on the voltage difference ΔV with respect to the fuel cell 15, and then an accurate increase amount Sb (for example, 5% as the increase rate) of the air bleed amount to the fuel cell 15 is obtained. . Then, the control unit 101 sets the accurate increase amount Sb of the air bleed amount as the increase amount of the air bleed amount of the air bleed mechanism 12 (step SS6), and then ends the diagnostic step S3.

  If the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS5), the control unit 101 derives an accurate increase amount Sb of the ruthenium residual rate and the air bleed amount. And the diagnostic step S3 is terminated without setting.

  Next, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is lower than the reference voltage value Vs (YES in step SS5), the air bleed amount Sn + Sb is controlled by controlling the air bleed mechanism 12. The supply of air to the reformed gas is started at a supply amount of (step S4a). On the other hand, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS5), the control unit 101 maintains the air bleed amount Sn and returns to the reformed gas. The air supply is started (step S4b).

  At this time, the supply of air to the reformed gas by the air bleed mechanism 12 is not necessarily performed. In other words, the configuration may be such that the controller 101 only changes the air bleed amount setting in the diagnosis step S3 and applies the air bleed amount that is changed during the normal power generation operation of the fuel cell system 100 next time.

  The control unit 101 determines that the temperature of the fuel cell 15 has decreased to a predetermined temperature (for example, 40 ° C.), and the raw material flow rate adjustment valve 1, the reforming water supply pump 8, and the combustion city gas supply valve. 9 and the combustion air supply valve 10 are completely closed, the temperature Tsr of the reformer 3 is lowered to a predetermined temperature (for example, 300 ° C.), and the temperature Ts of the transformer 4 is The temperature Tp of the purifier 5 is lowered to a predetermined temperature (for example, 100 ° C.) and the temperature Tfr of the fuel reforming unit 7 is lowered to the predetermined temperature Tpd. If it is determined that it has decreased (YES in step S5), the operation of the fuel reforming unit 7 and other components is completely stopped, and the operation of the fuel cell system 100 is completely stopped (step S6).

  If the control unit 101 determines that the temperature Tfr of the fuel reforming unit 7 has not decreased to the predetermined temperature Tpd (NO in step S5), the change in the temperature Tfr of the fuel reforming unit 7 is detected by the temperature sensor. Continue to monitor. Then, the control unit 101 repeatedly determines whether or not the temperature Tfr of the fuel reforming unit 7 has decreased to a predetermined temperature Tpd.

  As described above, in the fuel cell system 100 shown in the present embodiment, when the fuel cell system 100 is stopped, the temperature Ts of the transformer 4 reaches the diagnostic temperature Td that is lower than the predetermined temperature Tpd for the shift reaction. When it decreases, a reformed gas that temporarily contains carbon monoxide at a high concentration is supplied from the fuel reformer 7 to the fuel cell 15. As a result, the voltage difference ΔV between the output voltage value Vd of the fuel cell 15 and the reference voltage value Vs is accurately detected, the ruthenium residual rate in the platinum-ruthenium alloy catalyst of the fuel cell 15 is accurately obtained, and the fuel is improved. The amount of air bleed into the reformed gas generated by the mass part 7 is accurately increased. Even with such a configuration, it is possible to obtain the same effects as in the first to third embodiments.

  Further, according to the present embodiment, when the fuel cell system 100 is in a stop operation, there is necessarily a time when the temperature Ts of the transformer 4 becomes equal to the diagnostic temperature Td every day. It is possible to easily obtain a reformed gas that temporarily contains carbon monoxide at a high concentration without performing the above steps and without preparing special components.

  Other points are the same as those in the first to third embodiments.

(Embodiment 5)
In the fifth embodiment according to the present invention, the control method for obtaining the reformed gas containing carbon monoxide for diagnostic operation is different from the control method in the fourth embodiment.

  Specifically, when determining whether to start the diagnostic operation of the fuel cell 15 during the stop operation of the fuel cell system 100, in Embodiment 4, instead of detecting the temperature Ts of the transformer 4, In the fifth embodiment, the temperature Tp of the purifier 5 is detected. Then, it is determined whether or not the temperature Tp of the purifier 5 has decreased to a diagnostic temperature Td that is lower than a predetermined temperature Tpd for causing the selective oxidation reaction to proceed. When the temperature drops to Td, the reformed gas containing carbon monoxide for diagnostic operation generated by the fuel reforming unit 7 is supplied to the fuel cell 15. Then, the diagnostic operation of the fuel cell 15 is started. In addition, after the temperature Tfr of the fuel reforming unit 7 has decreased to the predetermined temperature Tpd and the temperature of the fuel cell 15 has decreased to the predetermined temperature, the operation of the fuel cell system 100 is completely stopped.

  In other respects, the configuration and operation of the fuel cell system 100 shown in the fifth embodiment are the same as the configuration and operation of the fuel cell system 100 shown in the fourth embodiment. Therefore, in the fifth embodiment, regarding the configuration and operation of the fuel cell system 100, the description of the same configuration and operation as those described in the fourth embodiment is omitted.

  Hereinafter, with respect to the operation of the fuel cell system 100 of the fifth embodiment, differences from the operation of the fuel cell system 100 shown in the fourth embodiment will be described in detail with reference to FIG.

  FIG. 8 is a flowchart schematically showing an operation during stop operation of fuel cell system 100 shown in Embodiment 5 of the present invention. In FIG. 8, step S3 indicates a diagnostic step for determining an optimum increase amount of the air bleed amount based on the output voltage value Vd of the fuel cell 15 during the stop operation.

  As shown in FIG. 8, in the fuel cell system 100 of the fifth embodiment, after the normal power generation operation of the fuel cell 15 is stopped (step S1), cooling of the fuel reforming unit 7 is started (step S2). Diagnosis step S3 (step SS1 to step SS6) for determining an optimum increase amount Sb of the air bleed amount on the basis of the output voltage value Vd of the battery 15 proceeds.

  The control unit 101 sequentially monitors changes in the temperature Tp of the purifier 5 in the fuel reforming unit 7 using a temperature sensor. On the other hand, the temperature Tp of the purifier 5 is directly decreased by decreasing the supply amount of city gas to the desulfurizer 2 and the supply amount of water to the reformer 3 or by stopping supply of city gas to the combustor 6. Or it cools indirectly and falls gradually. Then, the controller 101 reduces the temperature Tp of the purifier 5 to a diagnostic temperature Td (eg, 90 ° C.) that is lower than a predetermined temperature Tpd (eg, 150 ° C.) for causing the selective oxidation reaction to proceed. Whether or not (step SS1).

  When the control unit 101 determines that the temperature Tp of the purifier 5 has decreased to the diagnostic temperature Td (YES in step SS1), the fuel reforming unit 7 shows a diagram when the temperature Tp of the purifier 5 is the diagnostic temperature Td. The reformed gas containing carbon monoxide corresponding to the CO concentration C2 shown in FIG. 2 (for example, 120 ppm) is started to be supplied from the purifier 5 to the fuel cell 15 at a predetermined supply amount. At this time, the control unit 101 controls the air flow rate adjusting unit 17. Thereby, the humidifier 18 starts to supply air to the fuel cell 15 at a predetermined supply amount. And the control part 101 starts the diagnostic driving | operation of the fuel cell 15 (step SS2).

  If the control unit 101 determines that the temperature Tp of the purifier 5 has not yet decreased to the diagnostic temperature Td (NO in step SS1), the control unit 101 continues to monitor the change in the temperature Tp of the purifier 5 using the temperature sensor. Then, the controller 101 repeatedly determines whether or not the temperature Tp of the purifier 5 has decreased to the diagnostic temperature Td.

  Next, after measuring the output voltage value Vd of the fuel cell 15 during the diagnostic operation (Step SS3), the control unit 101 ends the diagnostic operation of the fuel cell 15 (Step SS4).

  Next, the control unit 101 compares the output voltage value Vd of the fuel cell 15 measured and stored in step SS3 with the reference voltage value Vs, and determines whether or not the output voltage value Vd is lower than the reference voltage value Vs. (Step SS5).

  When the control unit 101 determines that the output voltage value Vd (for example, 730 mV) of the fuel cell 15 is lower than the reference voltage value Vs (for example, 750 mV) (YES in step SS5), the reference voltage value Vs and the output voltage value Vd. The ruthenium residual rate in the platinum-ruthenium alloy catalyst is accurately obtained based on the voltage difference ΔV with respect to the fuel cell 15, and then an accurate increase amount Sb (for example, 5% as the increase rate) of the air bleed amount to the fuel cell 15 is obtained. . Then, the control unit 101 sets the accurate increase amount Sb of the air bleed amount as the increase amount of the air bleed amount of the air bleed mechanism 12 (step SS6), and then ends the diagnostic step S3.

  If the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS5), the control unit 101 derives an accurate increase amount Sb of the ruthenium residual rate and the air bleed amount. And the diagnostic step S3 is terminated without setting.

  Next, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is lower than the reference voltage value Vs (YES in step SS5), the air bleed amount Sn + Sb is controlled by controlling the air bleed mechanism 12. The supply of air to the reformed gas is started at a supply amount of (step S4a). On the other hand, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS5), the control unit 101 maintains the air bleed amount Sn and returns to the reformed gas. The air supply is started (step S4b).

  Then, the control unit 101 determines that the temperature of the fuel cell 15 has decreased to a predetermined temperature (for example, 40 ° C.), and the temperature Tsr of the reformer 3 has decreased to a predetermined temperature (for example, 300 ° C.). The temperature Ts of the transformer 4 is reduced to a predetermined temperature (for example, 200 ° C.), the temperature Tp of the purifier 5 is decreased to a predetermined temperature (for example, 100 ° C.), and the fuel is improved. If it is determined that the temperature Tfr of the mass portion 7 has decreased to the predetermined temperature Tpd (YES in step S5), the operation of the fuel cell system 100 is completely stopped (step S6).

  If the control unit 101 determines that the temperature Tfr of the fuel reforming unit 7 has not decreased to the predetermined temperature Tpd (NO in step S5), the change in the temperature Tfr of the fuel reforming unit 7 is detected by the temperature sensor. Continue to monitor. Then, the control unit 101 repeatedly determines whether or not the temperature Tfr of the fuel reforming unit 7 has decreased to a predetermined temperature Tpd.

  As described above, in the fuel cell system 100 shown in the present embodiment, when the fuel cell system 100 is stopped, the temperature Tp of the purifier 5 is set to the diagnostic temperature Td that is lower than the predetermined temperature Tpd for the selective oxidation reaction. When the fuel gas is reduced to a low level, the reformed gas that temporarily contains carbon monoxide at a high concentration is supplied from the fuel reformer 7 to the fuel cell 15. As a result, the voltage difference ΔV between the output voltage value Vd of the fuel cell 15 and the reference voltage value Vs is accurately detected, the ruthenium residual rate in the platinum-ruthenium alloy catalyst of the fuel cell 15 is accurately obtained, and the fuel is improved. The amount of air bleed into the reformed gas generated by the mass part 7 is accurately increased. Even with this configuration, it is possible to obtain the same effect as in the fourth embodiment.

  Further, according to the present embodiment, when the fuel cell system 100 is in a stop operation, there is always a point in time when the temperature Tp of the purifier 5 becomes equal to the diagnosis temperature Td. It is possible to easily obtain a reformed gas that temporarily contains carbon monoxide at a high concentration without performing the above steps and without preparing special components.

  Other points are the same as those in the first to fourth embodiments.

(Embodiment 6)
In the sixth embodiment according to the present invention, the control method for obtaining the reformed gas containing carbon monoxide for diagnostic operation is different from the control method in the fourth and fifth embodiments.

  Specifically, in the fourth and fifth embodiments, when the diagnostic operation of the fuel cell 15 is started, the temperature Ts of the transformer 4 or the temperature Tp of the purifier 5 is a predetermined value for causing a shift reaction or a selective oxidation reaction to proceed. When the temperature drops to a diagnostic temperature Td, which is lower than the temperature Tpd, the reformed gas containing carbon monoxide for diagnostic operation generated by the fuel reformer is supplied to the fuel cell. Instead, in the fuel cell system 100 of the sixth embodiment, after the normal power generation operation of the fuel cell 15 is stopped, the supply amount of air to the purifier 5 is reduced or the supply is stopped to perform the diagnostic operation. A reformed gas containing carbon monoxide is obtained. Then, the reformed gas containing carbon monoxide for diagnostic operation generated by the fuel reforming unit 7 is supplied to the fuel cell 15 and the diagnostic operation of the fuel cell 15 is started. Further, the decrease in the supply amount of air to the purifier 5 or the stoppage of the supply is canceled, and the temperature Tfr of the fuel reforming unit 7 (that is, the temperature Tsr of the reformer 3, the temperature Ts of the transformer 4, the purifier After the temperature Tp) of 5 has dropped to the predetermined temperature Tpd, the operation of the fuel cell system 100 is completely stopped.

  In other respects, the configuration and operation of the fuel cell system 100 shown in the sixth embodiment are the same as the configuration and operation of the fuel cell system 100 shown in the fourth and fifth embodiments. Therefore, in the sixth embodiment, regarding the configuration and operation of the fuel cell system 100, the description of the same configuration and operation as those described in the fourth and fifth embodiments is omitted.

  Hereinafter, with respect to the operation of the fuel cell system 100 of the sixth embodiment, differences from the operation of the fuel cell system 100 shown in the fourth and fifth embodiments will be described in detail with reference to FIG.

  FIG. 9 is a flowchart schematically showing an operation during stop operation of fuel cell system 100 shown in Embodiment 6 of the present invention. In FIG. 9, step S <b> 2 indicates a diagnostic step for determining an optimal increase amount of the air bleed amount based on the output voltage value Vd of the fuel cell 15 during the stop operation.

  As shown in FIG. 9, in the fuel cell system 100 of the sixth embodiment, after the normal power generation operation of the fuel cell 15 is stopped (step S1), the optimum air bleed amount is determined based on the output voltage value Vd of the fuel cell 15. The diagnostic step S2 (step SS1 to step SS7) for determining a large increase amount Sb proceeds.

  After stopping the normal power generation operation of the fuel cell 15 (step S1), the control unit 101 controls the selective oxidation flow rate adjustment unit 11 to reduce the amount of air supplied from the air flow rate adjustment unit 17 to the purifier 5. (Step SS1). Alternatively, after stopping the normal power generation operation of the fuel cell 15, the control unit 101 controls the selective oxidation flow rate adjustment unit 11 to stop the supply of air from the air flow rate adjustment unit 17 to the purifier 5. By the control shown in step SS1, the concentration of carbon monoxide in the reformed gas generated by the fuel reforming unit 7 increases.

  Next, the fuel reforming unit 7 is shown in FIG. 2 after the amount of air supplied from the air flow rate adjusting unit 17 to the purifier 5 is reduced at a predetermined reduction rate (for example, 50% during normal power generation operation). The reformed gas containing carbon monoxide at a concentration (for example, 150 ppm) corresponding to the CO concentration C2 is started to be supplied from the purifier 5 to the fuel cell 15 at a predetermined supply amount. At this time, the control unit 101 controls the air flow rate adjusting unit 17. Thereby, the humidifier 18 starts to supply air to the fuel cell 15 at a predetermined supply amount. And the control part 101 starts the diagnostic driving | operation of the fuel cell 15 (step SS2).

  Next, after measuring the output voltage value Vd of the fuel cell 15 during the diagnostic operation (Step SS3), the control unit 101 ends the diagnostic operation of the fuel cell 15 (Step SS4).

  Next, after the diagnostic operation of the fuel cell 15 is completed, the control unit 101 controls the selective oxidation flow rate adjusting unit 11 to return the amount of air supplied from the air flow rate adjusting unit 17 to the purifier 5 (step). SS5). Alternatively, after the diagnostic operation of the fuel cell 15 is completed, the control unit 101 controls the selective oxidation flow rate adjustment unit 11 to restore the stop of air supply from the air flow rate adjustment unit 17 to the purifier 5. By the control shown in step SS5, the concentration of carbon monoxide in the reformed gas generated by the fuel reforming unit 7 is restored.

  Next, the control unit 101 compares the output voltage value Vd of the fuel cell 15 measured and stored in step SS3 with the reference voltage value Vs, and determines whether or not the output voltage value Vd is lower than the reference voltage value Vs. (Step SS6).

  When the control unit 101 determines that the output voltage value Vd (for example, 720 mV) of the fuel cell 15 is lower than the reference voltage value Vs (for example, 730 mV) (YES in step SS6), the control voltage value Vs and the output voltage value Vd. The ruthenium residual rate in the platinum-ruthenium alloy catalyst is accurately obtained based on the voltage difference ΔV with respect to the fuel cell 15, and then an accurate increase amount Sb (for example, 6% as the increase rate) of the air bleed amount to the fuel cell 15 is obtained. . Then, the control unit 101 sets the accurate increase amount Sb of the air bleed amount as the increase amount of the air bleed amount of the air bleed mechanism 12 (step SS7), and then ends the diagnosis step S2.

  If the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS6), the control unit 101 derives an accurate increase amount Sb of the ruthenium remaining rate and the air bleed amount. And the diagnostic step S2 is finished without setting.

  Next, when the control unit 101 determines that the value of the output voltage value Vd of the fuel cell 15 is lower than the value of the reference voltage value Vs (YES in step SS6), the control unit 101 controls the air bleed mechanism 12 to Supply of air to the reformed gas is started with the supply amount of air bleed amount Sn + Sb (step S3a). On the other hand, when the control unit 101 determines that the output voltage value Vd of the fuel cell 15 is not lower than the reference voltage value Vs (NO in step SS6), the control unit 101 maintains the air bleed amount Sn and returns to the reformed gas. The air supply is started (step S3b).

  Thereafter, the control unit 101 starts cooling the fuel reforming unit 7 (step S4).

  The control unit 101 sequentially monitors changes in the temperature Tsr of the reformer 3, the temperature Ts of the transformer 4, and the temperature Tp of the purifier 5 in the fuel reforming unit 7 using temperature sensors. On the other hand, the temperature Tsr of the reformer 3, the temperature Ts of the transformer 4, and the temperature Tp of the purifier 5 are reduced in the amount of city gas supplied to the desulfurizer 2 and the amount of water supplied to the reformer 3, or It is cooled directly or indirectly by stopping the supply of city gas to the combustor 6 and gradually decreases. Then, the control unit 101 determines that the temperature of the fuel cell 15 has decreased to a predetermined temperature (for example, 40 ° C.), and the temperature Tsr of the reformer 3 has decreased to a predetermined temperature (for example, 300 ° C.). The temperature Ts of the transformer 4 is reduced to a predetermined temperature (for example, 200 ° C.), the temperature Tp of the purifier 5 is decreased to a predetermined temperature (for example, 100 ° C.), and the fuel is improved. If it is determined that the temperature Tfr of the mass portion 7 has decreased to the predetermined temperature Tpd (YES in step S5), the operation of the fuel cell system 100 is completely stopped (step S6).

  If the control unit 101 determines that the temperature Tfr of the fuel reforming unit 7 has not decreased to the predetermined temperature Tpd (NO in step S5), the change in the temperature Tfr of the fuel reforming unit 7 is detected by the temperature sensor. Continue to monitor. Then, the control unit 101 repeatedly determines whether or not the temperature Tfr of the fuel reforming unit 7 has decreased to a predetermined temperature Tpd.

  As described above, in the fuel cell system 100 shown in the present embodiment, during the stop operation of the fuel cell system 100, after the normal power generation operation of the fuel cell 15 is stopped, the flow rate adjustment unit 11 for selective oxidation is controlled to adjust the air flow rate. By reducing or stopping the supply of air from the unit 17 to the purifier 5 in the fuel reforming unit 7, the reformed gas that temporarily contains carbon monoxide at a high concentration is supplied from the fuel reforming unit 7 to the fuel. The battery 15 is supplied. As a result, the voltage difference ΔV between the output voltage value Vd of the fuel cell 15 and the reference voltage value Vs is accurately detected, the ruthenium residual rate in the platinum-ruthenium alloy catalyst of the fuel cell 15 is accurately obtained, and the fuel is improved. The amount of air bleed into the reformed gas generated by the mass part 7 is accurately increased. Even with such a configuration, it is possible to obtain the same effects as those of the fourth and fifth embodiments.

  Further, according to the present embodiment, when the fuel cell system 100 is stopped, the selective oxidation flow rate adjusting unit 11 is controlled to supply air from the air flow rate adjusting unit 17 to the purifier 5 in the fuel reforming unit 7. It is very easy to reduce the volume or stop the supply, so that the carbon monoxide is temporarily increased without any special operation or preparation of special components during the shutdown operation. The reformed gas included in the concentration can be easily obtained.

  Other points are the same as those in the fourth and fifth embodiments.

(Embodiment 7)
In the first to third embodiments according to the present invention, the mode of increasing the amount of air bleed to the reformed gas based on the result of the diagnostic operation of the fuel cell 15 during the start-up operation of the fuel cell system 100 has been described. On the other hand, in Embodiments 4 to 6 according to the present invention, the mode of increasing the amount of air bleed to the reformed gas based on the result of the diagnostic operation of the fuel cell 15 during the stop operation of the fuel cell system 100 has been described.

  By the way, in the best mode for carrying out the present invention, the time when the diagnostic operation of the fuel cell 15 is executed is any time during the start-up operation of the fuel cell system 100 or the stop operation of the fuel cell system 100. It is not necessary to limit to. That is, in the best mode for carrying out the present invention, the diagnostic operation of the fuel cell 15 is performed during the start-up operation or the stop operation of the fuel cell system 100 as in the first to third embodiments or the fourth to fourth embodiments. It is good also as a form performed at both the time of the starting operation of the fuel cell system 100, and a stop operation other than the form performed at any time of these.

  Hereinafter, a mode in which the diagnosis operation of the fuel cell 15 is executed at both the start-up operation time and the stop-operation time of the fuel cell system 100 will be described with a plurality of examples. Note that the configuration exemplified in the seventh embodiment is a combination of the configurations shown in the first to sixth embodiments. Therefore, in Embodiment 7, only the example of the combined configuration of Embodiments 1 to 6 is shown, and for the detailed description of each embodiment, refer to the description in Embodiments 1 to 6 and FIGS. I will omit it.

  Further, the configuration and basic operation of the fuel cell system 100 used in the seventh embodiment are the same as the configuration and basic operation of the fuel cell system 100 described in the first to sixth embodiments. Therefore, in Embodiment 7, the description regarding the structure and basic operation of the fuel cell system 100 common to Embodiments 1 to 6 is omitted.

  First, the first embodiment according to the seventh embodiment can include a combination of the first embodiment and the fourth embodiment (see FIGS. 4 and 7). In the form in which the first embodiment and the fourth embodiment are combined, when the temperature Ts of the transformer 4 of the fuel reforming unit 7 reaches the diagnostic temperature Td during the start-up operation of the fuel cell system 100, the fuel cell 15 Then, the amount of air bleed into the reformed gas is corrected as necessary based on the result of the diagnostic operation. Further, when the temperature Ts of the transformer 4 of the fuel reforming unit 7 is lowered to the diagnostic temperature Td during the stop operation of the fuel cell system 100, the diagnostic operation of the fuel cell 15 is performed, and based on the result of the diagnostic operation. The amount of air bleed into the reformed gas is corrected as necessary.

  Further, as the second embodiment according to the seventh embodiment, a combination of the first embodiment and the fifth embodiment can be cited (see FIGS. 4 and 8). In the form in which the first embodiment and the fifth embodiment are combined, when the temperature Ts of the transformer 4 of the fuel reforming unit 7 reaches the diagnostic temperature Td during the start-up operation of the fuel cell system 100, the fuel cell 15 Then, the amount of air bleed into the reformed gas is corrected as necessary based on the result of the diagnostic operation. Further, when the temperature Tp of the purifier 5 of the fuel reformer 7 is lowered to the diagnostic temperature Td during the stop operation of the fuel cell system 100, the diagnostic operation of the fuel cell 15 is performed, and based on the result of this diagnostic operation. The amount of air bleed into the reformed gas is corrected as necessary.

  Further, as the third embodiment according to the seventh embodiment, a combination of the first embodiment and the sixth embodiment can be cited (see FIGS. 4 and 9). In the form in which the first embodiment and the sixth embodiment are combined, when the temperature Ts of the transformer 4 of the fuel reforming unit 7 reaches the diagnostic temperature Td during the start-up operation of the fuel cell system 100, the fuel cell 15 Then, the amount of air bleed into the reformed gas is corrected as necessary based on the result of the diagnostic operation. In addition, during the stop operation of the fuel cell system 100, the amount of air supplied to the purifier 5 of the fuel reforming unit 7 is reduced to perform the diagnosis operation of the fuel cell 15, and based on the result of this diagnosis operation, the improvement is made. Correct the amount of air bleed into the quality gas as necessary.

  Further, as a fourth embodiment according to the seventh embodiment, a combination of the second embodiment and the fourth embodiment can be given (see FIGS. 5 and 7). In the form in which the second embodiment and the fourth embodiment are combined, when the temperature Tp of the purifier 5 of the fuel reforming unit 7 reaches the diagnostic temperature Td during the start-up operation of the fuel cell system 100, the fuel cell 15 Then, the amount of air bleed into the reformed gas is corrected as necessary based on the result of the diagnostic operation. Further, when the temperature Ts of the transformer 4 of the fuel reforming unit 7 is lowered to the diagnostic temperature Td during the stop operation of the fuel cell system 100, the diagnostic operation of the fuel cell 15 is performed, and based on the result of the diagnostic operation. The amount of air bleed into the reformed gas is corrected as necessary.

  Further, as a fifth embodiment according to the seventh embodiment, a combination of the second embodiment and the fifth embodiment can be given (see FIGS. 5 and 8). In the embodiment in which the second embodiment and the fifth embodiment are combined, when the temperature Tp of the purifier 5 of the fuel reforming unit 7 reaches the diagnostic temperature Td during the start-up operation of the fuel cell system 100, the fuel cell 15 Then, the amount of air bleed into the reformed gas is corrected as necessary based on the result of the diagnostic operation. Further, when the temperature Tp of the purifier 5 of the fuel reformer 7 is lowered to the diagnostic temperature Td during the stop operation of the fuel cell system 100, the diagnostic operation of the fuel cell 15 is performed, and based on the result of this diagnostic operation. The amount of air bleed into the reformed gas is corrected as necessary.

  Further, as a sixth embodiment according to the seventh embodiment, a combination of the second embodiment and the sixth embodiment can be given (see FIGS. 5 and 9). In the embodiment in which the second embodiment and the sixth embodiment are combined, when the temperature Tp of the purifier 5 of the fuel reforming unit 7 reaches the diagnostic temperature Td during the start-up operation of the fuel cell system 100, the fuel cell 15 Then, the amount of air bleed into the reformed gas is corrected as necessary based on the result of the diagnostic operation. In addition, during the stop operation of the fuel cell system 100, the amount of air supplied to the purifier 5 of the fuel reforming unit 7 is reduced to perform the diagnosis operation of the fuel cell 15, and based on the result of this diagnosis operation, the improvement is made. Correct the amount of air bleed into the quality gas as necessary.

  Further, as a seventh embodiment according to the seventh embodiment, a combination of the third embodiment and the fourth embodiment can be given (see FIGS. 6 and 7). In the embodiment in which the third embodiment and the fourth embodiment are combined, the amount of air supplied to the purifier 5 of the fuel reforming unit 7 during the start-up operation of the fuel cell system 100 is reduced to reduce the fuel cell 15 A diagnostic operation is performed, and the air bleed amount to the reformed gas is corrected as necessary based on the result of the diagnostic operation. Further, when the temperature Ts of the transformer 4 of the fuel reforming unit 7 is lowered to the diagnostic temperature Td during the stop operation of the fuel cell system 100, the diagnostic operation of the fuel cell 15 is performed, and based on the result of the diagnostic operation. The amount of air bleed into the reformed gas is corrected as necessary.

  Further, as an eighth embodiment according to the seventh embodiment, a combination of the third embodiment and the fifth embodiment can be given (see FIGS. 6 and 8). In the embodiment in which the third embodiment and the fifth embodiment are combined, the amount of air supplied to the purifier 5 of the fuel reforming unit 7 during the start-up operation of the fuel cell system 100 is reduced to reduce the fuel cell 15 A diagnostic operation is performed, and the air bleed amount to the reformed gas is corrected as necessary based on the result of the diagnostic operation. Further, when the temperature Tp of the purifier 5 of the fuel reformer 7 is lowered to the diagnostic temperature Td during the stop operation of the fuel cell system 100, the diagnostic operation of the fuel cell 15 is performed, and based on the result of this diagnostic operation. The amount of air bleed into the reformed gas is corrected as necessary.

  Furthermore, the ninth embodiment according to the seventh embodiment can include a combination of the third embodiment and the sixth embodiment (see FIGS. 6 and 9). In the embodiment in which the third embodiment and the sixth embodiment are combined, the amount of air supplied to the purifier 5 of the fuel reforming unit 7 during the start-up operation of the fuel cell system 100 is reduced to reduce the fuel cell 15 A diagnostic operation is performed, and the air bleed amount to the reformed gas is corrected as necessary based on the result of the diagnostic operation. In addition, during the stop operation of the fuel cell system 100, the amount of air supplied to the purifier 5 of the fuel reforming unit 7 is reduced to perform the diagnosis operation of the fuel cell 15, and based on the result of this diagnosis operation, the improvement is made. Correct the amount of air bleed into the quality gas as necessary.

  As described above, according to the present embodiment, the diagnosis operation of the fuel cell 15 is executed at the time of both the start operation and the stop operation of the fuel cell system 100, so that the start operation and the stop operation are performed. Since the deterioration state of the anode catalyst of the fuel cell 15 can be diagnosed at both times, it is possible to adjust the increase amount of the air bleed amount with higher accuracy.

  Other points are the same as those in the first to sixth embodiments.

  The fuel cell system according to the present invention is capable of accurately grasping the performance deterioration of the anode catalyst of the fuel cell with a simple configuration and accurately increasing the amount of air bleed, and has excellent durability and power generation efficiency. As a suitable fuel cell system having the stability of the output voltage value during the power generation operation, it can be used industrially.

  Moreover, the fuel cell power generation system according to the present invention can be industrially used as a fuel cell system used in portable devices, electric vehicles, household cogeneration systems, and the like.

It is a block diagram which shows typically a part of structure of the fuel cell system shown in Embodiment 1 of this invention. It is a schematic diagram explaining the principle for calculating | requiring the residual rate of ruthenium correctly in a platinum-ruthenium alloy catalyst. The correlation between the difference between the output voltage value of the fuel cell and the reference voltage value stored in the control unit of the fuel cell system, the residual rate of ruthenium in the platinum-ruthenium alloy catalyst, and the optimum increase in the air bleed amount It is a data table shown. 3 is a flowchart schematically showing an operation during start-up operation of the fuel cell system shown in Embodiment 1 of the present invention. 6 is a flowchart schematically showing an operation during start-up operation of the fuel cell system shown in Embodiment 2 of the present invention. 6 is a flowchart schematically showing an operation during start-up operation of the fuel cell system shown in Embodiment 3 of the present invention. 6 is a flowchart schematically showing an operation during a stop operation of the fuel cell system shown in Embodiment 4 of the present invention. 10 is a flowchart schematically showing an operation during a stop operation of the fuel cell system shown in Embodiment 5 of the present invention. It is a flowchart which shows typically the operation | movement at the time of the stop driving | operation of the fuel cell system shown in Embodiment 6 of this invention. It is a block diagram which shows typically a part of general structure of the conventional fuel cell system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material flow control valve 2 Desulfurizer 3 Reformer 4 Transformer 5 Purifier 6 Combustor 7 Fuel reforming part 8 Reformed water supply pump 9 City gas supply valve for combustion 10 Air supply valve for combustion 11 Flow for selective oxidation Adjustment part 12 Air bleed mechanism 13 Bypass valve 14 Bypass path 15 Fuel cell 16 Heat exchange part 17 Air flow rate adjustment part 18 Humidifier 18a Air flow path 18b Exhaust air flow path 18c Polymer electrolyte membrane 19 Condenser 20 Control part 101 Raw material flow rate adjustment valve 102 Desulfurizer 103 Reformer 104 Transformer 105 Purifier 106 Fuel reforming unit 107 Reformed water supply pump 108 Flow rate adjusting unit for selective oxidation 109 Fuel cell 110 Heat exchange unit 111 Air flow rate adjusting unit 112 Humidifier 113 Air bleed mechanism 114 Combustor 100, 200 Fuel cell system

Claims (12)

An air bleed mechanism for supplying air;
An oxidant gas supply unit for supplying an oxidant gas;
A fuel gas supply unit for reforming the raw material and supplying a fuel gas containing hydrogen;
A gas mixture of the fuel gas and the air obtained by the air bleed mechanism supplying the air to the fuel gas supplied by the fuel gas supply unit; A fuel cell that generates electricity using
A fuel cell system including at least the air bleed mechanism, the oxidant gas supply unit, the fuel gas supply unit, and a control unit that controls the fuel cell to perform start-up operation and stop operation,
The control unit diagnoses a decrease in performance of the anode catalyst of the fuel cell during the start-up operation, and controls the air bleed mechanism based on a result of the diagnosis to control the supply amount of the air to the fuel gas. Increase the fuel cell system.   Based on a voltage difference between an output voltage value of the fuel cell and a predetermined reference voltage value when the control unit supplies the fuel gas having a carbon monoxide concentration exceeding that during normal power generation operation. The fuel cell system according to claim 1, wherein the diagnosis is performed. The fuel gas supply unit includes a transformer that reduces the carbon monoxide concentration of the fuel gas to a first temperature or higher and a first concentration or lower;
The control unit determines that the temperature of the transformer is lower than the first temperature, and the transformer reduces the carbon monoxide concentration of the fuel gas so as to exceed the first concentration. The fuel cell system according to claim 2, wherein the fuel gas having a carbon monoxide concentration exceeding that during power generation operation is supplied. The fuel gas supply unit includes a purifier that reduces the carbon monoxide concentration of the fuel gas to a second temperature or higher but not lower than a second temperature;
The control unit determines that the temperature of the purifier is lower than the second temperature, and the purifier reduces the carbon monoxide concentration of the fuel gas to exceed the second concentration. The fuel cell system according to claim 2, wherein the fuel gas having a carbon monoxide concentration exceeding that during power generation operation is supplied. An air supply unit for supplying air at a predetermined flow rate or more to the purifier in order to reduce the carbon monoxide concentration of the fuel gas from the second temperature to the second concentration;
The control unit determines that at least the temperatures of the transformer and the purifier are equal to or higher than the first and second temperatures, and the air supply unit supplies or stops supplying the air below the predetermined flow rate. The fuel cell system according to claim 2, wherein the fuel gas having a carbon monoxide concentration exceeding that during the normal power generation operation is supplied. An air bleed mechanism for supplying air;
An oxidant gas supply unit for supplying an oxidant gas;
A fuel gas supply unit for reforming the raw material and supplying a fuel gas containing hydrogen;
A gas mixture of the fuel gas and the air obtained by the air bleed mechanism supplying the air to the fuel gas supplied by the fuel gas supply unit; A fuel cell that generates electricity using
A fuel cell system including at least the air bleed mechanism, the oxidant gas supply unit, the fuel gas supply unit, and a control unit that controls the fuel cell to perform start-up operation and stop operation,
The control unit diagnoses a decrease in performance of the anode catalyst of the fuel cell during the stop operation, and controls the air bleed mechanism based on a result of the diagnosis to control the supply amount of the air to the fuel gas. Increase the fuel cell system.   Based on a voltage difference between an output voltage value of the fuel cell and a predetermined reference voltage value when the control unit supplies the fuel gas having a carbon monoxide concentration exceeding that during normal power generation operation. The fuel cell system according to claim 6, wherein the diagnosis is performed. The fuel gas supply unit includes a transformer that reduces the carbon monoxide concentration of the fuel gas to a first temperature or higher and a first concentration or lower;
The control unit determines that the temperature of the transformer is lower than the first temperature, and the transformer reduces the carbon monoxide concentration of the fuel gas so as to exceed the first concentration. The fuel cell system according to claim 7, wherein the fuel gas having a carbon monoxide concentration exceeding that during power generation operation is supplied. The fuel gas supply unit includes a purifier that reduces the carbon monoxide concentration of the fuel gas to a second temperature or higher but not lower than a second temperature;
The control unit determines that the temperature of the purifier is lower than the second temperature, and the purifier reduces the carbon monoxide concentration of the fuel gas to exceed the second concentration. The fuel cell system according to claim 7, wherein the fuel gas having a carbon monoxide concentration exceeding that during power generation operation is supplied. An air supply unit for supplying air at a predetermined flow rate or more to the purifier in order to reduce the carbon monoxide concentration of the fuel gas from the second temperature to the second concentration;
The control unit determines that at least the temperatures of the transformer and the purifier are equal to or higher than the first and second temperatures, and the air supply unit supplies or stops supplying the air below the predetermined flow rate. The fuel cell system according to claim 7, wherein the fuel gas having a carbon monoxide concentration exceeding that during the normal power generation operation is supplied.   2. The fuel cell system according to claim 1, wherein the control unit diagnoses a decrease in performance of the anode catalyst of the fuel cell during the start-up operation and also during the stop operation.   The fuel cell includes an anode catalyst on one surface of a polymer electrolyte membrane having proton conductivity and a cathode catalyst on the other surface, and at least the anode catalyst of the anode catalyst and the cathode catalyst is a platinum-ruthenium alloy catalyst. The fuel cell system according to claim 1, which is a polymer electrolyte fuel cell.

Images