JP2013105735A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system in which thermal runaway in a selective oxidizer provided in a hydrogen generator can be prevented.SOLUTION: The fuel cell system includes a temperature sensor 17 for detecting the temperature of a selective oxidation catalyst layer of a selective oxidizer 10, and a control unit 18. When the temperature of the selective oxidation catalyst layer of the selective oxidizer 10 which is detected by the temperature sensor 17 becomes equal to or higher than a first predetermined temperature, the control unit 18 performs control so that a maximum flow rate of a raw material supplied to the hydrogen generator 2 becomes smaller compared with that before the temperature of the selective oxidation catalyst layer of the selective oxidizer 10 becomes equal to or higher than the first predetermined temperature.

Description

  The present invention relates to a fuel cell system including a hydrogen generator that generates a fuel gas containing hydrogen from a raw material.

  In recent years, a wide demand is expected for a fuel cell system which is a household power generation system using a fuel cell. In addition, various technical developments have been carried out for the practical use and popularization of household fuel cell systems. Conventionally, in a fuel cell system, hydrogen necessary for power generation in a fuel cell is reformed by a hydrogen generator by mixing, for example, a hydrocarbon-based material such as kerosene, city gas, LPG, or an alcohol material such as methanol with steam. The structure obtained by this is adopted.

  As such a hydrogen generator, a hydrogen generator including a desulfurizer, a reformer, a shift converter, and a selective oxidizer is known (for example, see Patent Document 1). FIG. 7 shows a hydrogen generator provided in a conventional fuel cell system described in Patent Document 1. As shown in FIG.

  In such a hydrogen generator, the following processing is performed.

  First, in a desulfurizer 123 provided upstream of the hydrogen generator 101, sulfur compounds contained as impurities or as an odorant for leakage detection are removed from the raw material. The raw material from which the sulfur compound has been removed in the desulfurizer 123 is mixed with steam and steam reformed in the reformer 124 to be generated into a fuel gas containing hydrogen and carbon monoxide. The fuel gas generated by the reformer 124 is sent to the transformer 125, where carbon monoxide, which causes deterioration of the catalyst and the like included in the fuel cell, reacts with water and converted to carbon dioxide. The

  The fuel gas that has passed through the transformer 125 is sent to the selective oxidizer 126. In the selective oxidizer 126, the carbon monoxide remaining in the fuel gas is selectively oxidized and converted to carbon dioxide. This selective oxidation reaction occurs when air supplied as an oxygen-containing gas to the selective oxidizer 126 and carbon monoxide in the fuel gas are brought into contact in the presence of a selective oxidation catalyst.

JP 2008-230867 A

  However, in the hydrogen generator 101 used in the conventional fuel cell system, the amount of air supplied to the selective oxidizer 126 is determined according to the flow rate of the raw material supplied to the reformer 124. Therefore, the amount of air supplied to the selective oxidizer 126 is suitable for selective oxidation of carbon monoxide due to the reforming performance of the reformer 124 and the accuracy of the flowmeter that measures the flow rate of air supplied to the selective oxidizer 126. There was a risk of deviating from the amount. Since the selective oxidation reaction performed in the selective oxidizer 126 is an exothermic reaction, when the selective oxidation reaction proceeds with the supply of air, the temperature of the selective oxidation catalyst layer rises. Further, when the air supply amount is excessive, the selective oxidation reaction is performed. The reaction is further promoted, and the selective oxidation catalyst layer temperature further increases.

Further, in the selective oxidizer 126 of the hydrogen generator 101 used in the conventional fuel cell system, a methanation reaction (methanation) can occur as a side reaction along with the selective oxidation reaction. The methanation reaction includes a reaction in which carbon monoxide and hydrogen in the fuel gas react to generate methane, and a reaction in which carbon dioxide and hydrogen in the reformed gas react to generate methane. . Since this methanation reaction is an exothermic reaction, this reaction also raises the selective oxidation catalyst layer temperature.

  Accordingly, when the amount of air supplied to the selective oxidizer 126 becomes excessive, the selective oxidation catalyst layer temperature rises, and when the temperature exceeds a certain limit temperature, the methanation reaction suddenly occurs and the selective oxidation catalyst layer temperature rises rapidly. In this state, the methanation reaction is further accelerated by this temperature rise, and the selective oxidizer 126 is in a state where the temperature of the selective oxidation catalyst layer rapidly rises regardless of the amount of air supply, and the temperature control becomes impossible. There was a case of thermal runaway. As a result, when the thermal runaway occurs, an excessive temperature load is applied to the hydrogen generator 101, the performance of the catalyst of the hydrogen generator 101 deteriorates, and the fuel cell system lacks hydrogen as a fuel due to the methanation reaction. There was a problem that it was impossible to continue driving.

  Accordingly, the present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a fuel cell system capable of preventing thermal runaway in a selective oxidizer provided in a hydrogen generator. .

  In order to solve the above-described conventional problems, the fuel cell system of the present invention includes a fuel cell that generates power using fuel gas and air, and at least a selective oxidizer, and contains hydrogen using raw material, water, and air. A hydrogen generator for generating fuel gas, a temperature detector for detecting the temperature of the selective oxidizer, a raw material supplier for supplying raw material to the hydrogen generator, a water supplier for supplying water to the hydrogen generator, An air supply device that supplies air to the selective oxidizer, and a controller that controls the fuel cell, the raw material supply device, the water supply device, and the air supply device are provided. As a result, when the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature, the controller increases the maximum amount of the raw material supplied to the hydrogen generator compared to before the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature. The flow rate can be controlled to be small.

  In the fuel cell system of the present invention, when the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature, the controller supplies the hydrogen generator to the hydrogen generator as compared with before the temperature of the selective oxidizer exceeds the first predetermined temperature. The maximum flow rate of the raw material to be processed is controlled to be small, and thermal runaway can be prevented by reducing the amount of heat generated by oxidation in the selective oxidizer.

1 is a block diagram showing the configuration of a fuel cell system according to Embodiments 1, 3, 4, and 5 of the present invention. FIG. 3 is a block diagram showing a configuration of a fuel cell system according to Embodiment 2 of the present invention. Flow chart of power generation control of the fuel cell system in Embodiment 2 of the present invention Raw material flow rate control flowchart of the fuel cell system in Embodiment 3 of the present invention Air flow control flowchart of the fuel cell system in Embodiment 3 of the present invention Flow chart for controlling water flow rate of fuel cell system in Embodiment 3 of the present invention Block diagram showing the configuration of a conventional fuel cell system

A first invention includes a fuel cell that generates power using fuel gas and air, a hydrogen generator that includes at least a selective oxidizer, and generates a fuel gas containing hydrogen using raw material, water, and air, and a selection A temperature detector for detecting the temperature of the oxidizer, a raw material supplier for supplying raw material to the hydrogen generator, a water supplier for supplying water to the hydrogen generator, and an air supplier for supplying air to the selective oxidizer; , A fuel cell system comprising a fuel cell, a raw material supplier, a water supplier and a controller for controlling the air supplier. With this configuration, when the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature, the controller supplies the raw material supplied to the hydrogen generator as compared with before the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature. The maximum flow rate is controlled to be small, and the amount of heat generated by oxidation in the selective oxidizer can be reduced, so that thermal runaway can be prevented.

  In particular, in the second aspect of the invention, in addition to the fuel cell system of the first aspect of the invention, the controller is configured such that the flow rate of the raw material supplied to the hydrogen generator is not less than the raw material flow rate lower limit value and not more than the first raw material flow rate upper limit value. When the temperature of the selective oxidizer is equal to or higher than the first predetermined temperature, the flow rate of the raw material is controlled to be equal to or lower than the second raw material flow rate upper limit value which is smaller than the first raw material flow rate upper limit value. The upper limit value of the supply amount of the raw material necessary for power generation can be reduced to the second raw material flow rate upper limit value or less, so that the upper limit value of the oxidation heat generation amount in the selective oxidizer can be reduced, thereby preventing thermal runaway. it can.

  In particular, in the third aspect of the invention, in addition to the fuel cell system of the second aspect, after the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature, the controller lowers the second predetermined temperature. In this case, by controlling the raw material flow rate to be equal to or lower than the first raw material flow rate upper limit value, the raw material flow rate is lower than the first raw material flow rate upper limit value according to the temperature of the selective oxidizer while preventing thermal runaway. Therefore, the upper limit of the flow rate of the raw material can be restored.

  In the fourth aspect of the invention, in particular, in addition to the fuel cell system of the first aspect of the invention, the controller causes the output power amount to be generated to be in a range not less than the power generation amount lower limit value and not more than the first power generation amount upper limit value. When the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature, the output power amount is controlled to be equal to or lower than the second power generation amount upper limit value that is smaller than the first power generation amount upper limit value. It is possible to reduce the upper limit value of the oxidation calorific value in the selective oxidizer by reducing the upper limit value of the necessary raw material, water and air supply amounts to the respective flow rate upper limit values corresponding to the second power generation amount upper limit value. Therefore, thermal runaway can be prevented.

  In the fifth aspect of the invention, in particular, in addition to the fuel cell system of the second aspect of the invention, the controller becomes lower than the second predetermined temperature after the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature. In this case, by controlling the output power amount to be equal to or lower than the first power generation upper limit value, while preventing thermal runaway, the output power amount is within a range equal to or lower than the first power generation amount upper limit value according to the temperature of the selective oxidizer. Therefore, the upper limit of the output power amount can be restored.

  In the sixth aspect of the invention, in particular, in addition to the fuel cell system of the first aspect of the invention, the controller has a flow rate of air supplied to the hydrogen generator that is not less than the lower limit value of the air flow rate and not more than the upper limit value of the first air flow rate. When the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature, the air flow rate is controlled to be equal to or lower than the second air flow rate upper limit value which is smaller than the first air flow rate upper limit value, and The upper limit value of the flow rate of air supplied to the selective oxidizer of the hydrogen generator is set to the second upper limit value of the air flow rate by controlling the flow rate of the raw material based on the target flow rate of the raw material reset using the air flow rate. By reducing the flow rate of the raw material using the reduced air flow rate and reducing it, the upper limit value of the oxidation heat generation amount in the selective oxidizer can be reduced, thereby preventing thermal runaway. be able to.

In the seventh invention, in particular, in addition to the fuel cell system of the sixth invention, the controller lowers the temperature of the selective oxidizer below the second predetermined temperature after the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature. In this case, the air flow rate is controlled to be equal to or lower than the first air flow rate upper limit value, thereby preventing the thermal runaway and the air flow rate to be equal to or lower than the first air flow rate upper limit value according to the temperature of the selective oxidizer Since it can control so that it may become a range, the flow volume upper limit of air can be returned.

  In the eighth aspect of the invention, in particular, in addition to the fuel cell system of the first aspect of the invention, the controller is configured such that the flow rate of water supplied to the hydrogen generator is not less than the water flow rate lower limit value and not more than the first water flow rate upper limit value. When the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature, the flow rate of water is controlled to be equal to or lower than the second water flow rate upper limit value smaller than the first water flow rate upper limit value, and The upper limit value of the flow rate of water supplied to the hydrogen generator is less than or equal to the second upper limit value of the water flow rate by controlling the flow rate of the raw material based on the target flow rate of the raw material reset using the flow rate of the water. By reducing the flow rate of the raw material using the reduced flow rate of water and resetting it, the upper limit of the oxidation calorific value in the selective oxidizer can be reduced to prevent thermal runaway Can do.

  In the ninth aspect of the invention, in particular, in addition to the fuel cell system of the eighth aspect of the invention, the controller has a temperature lower than the second predetermined temperature after the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature. The water flow rate is controlled to be equal to or lower than the first water flow rate upper limit value, and the raw material flow rate control based on the raw material target flow rate reset by the first raw material target resetting means is stopped. Thus, the flow rate of water can be controlled to be within the range of the first water flow rate upper limit value or less according to the temperature of the selective oxidizer while preventing thermal runaway. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a fuel cell system according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the fuel cell system according to the present embodiment includes a fuel cell 1 that generates electricity using a fuel gas containing hydrogen and oxygen in the air, and hydrogen using a raw material, water, and air. A hydrogen generator 2 that generates a fuel gas containing hydrogen, a first pump 3 that supplies a raw material from a raw material supply source to the hydrogen generator 2, and a raw material from the raw material supply source generates hydrogen through the first pump 3 A raw material supply channel 4 arranged to be supplied to the hydrogen generator 2, a raw material flow meter 5 for detecting the flow rate of the raw material supplied to the hydrogen generator 1, and the fuel gas generated by the hydrogen generator 2 is a fuel cell A fuel gas supply flow path 6 disposed so as to be supplied to the fuel cell 1 and a fuel gas discharge flow path 7 disposed so that residual fuel gas not used for power generation in the fuel cell 1 is discharged from the fuel cell 1. I have. The hydrogen generator 2 includes a reformer 8 that generates a fuel gas containing hydrogen and carbon monoxide by performing steam reforming with a raw material and water, and is included in the fuel gas generated by the reformer 8. The carbon monoxide to be converted into carbon dioxide by reacting with carbon monoxide, and the carbon monoxide remaining in the fuel gas that has passed through the transformer 9 is selectively oxidized using oxygen to be converted into carbon dioxide The selective oxidizer 10 is provided.

  Further, a second pump 11 that supplies air containing oxygen to the selective oxidizer 10 of the hydrogen generator 2, and air that is arranged so that the air taken in by the second pump 11 is supplied to the selective oxidizer 10. From the supply flow path 12, the air flow meter 13 for detecting the flow rate of the air supplied to the selective oxidizer 10, the third pump 14 for supplying water from the water supply source to the hydrogen generator 2, and the water supply source Water flow path 15 arranged so that the water is supplied to the hydrogen generator 2 through the third pump 14, a water flow meter 16 for detecting the flow rate of the water supplied to the hydrogen generator 2, and selective oxidation A temperature sensor 17 for detecting the selective oxidation catalyst layer temperature of the vessel 10 and a control unit 18 are provided.

The raw material supply channel 4 has an upstream side connected to a raw material supply source and a downstream side connected to the hydrogen generator 2. The upstream side of the fuel gas supply channel 6 is connected to the hydrogen generator 2, and the downstream side is connected to the fuel cell 1. The upstream side of the fuel gas discharge channel 7 is connected to the fuel cell 1, and the downstream side is opened so that the remaining fuel gas is discharged outside the system. The air supply flow path 12 has an upstream side connected to the second pump 11 and a downstream side connected to the selective oxidizer 10. The water supply flow path 15 is connected to the water supply source on the upstream side and connected to the hydrogen generator 2 on the downstream side.

  The raw materials supplied from the raw material supply source include hydrocarbon gases such as methane and propane, hydrocarbon mixed gases obtained by removing odorous components from city gas and LP gas, kerosene, and alcohols such as methanol. Can be used. A cylinder cartridge or a gas infrastructure line can be used as the raw material supply source. In this embodiment, “residual fuel gas is discharged outside the system”, but it may be burned by a processing device such as a burner (not shown) and discharged as combustion exhaust gas outside the system.

  The temperature sensor 17, the first pump 3, the third pump 14, and the second pump 11 in the present embodiment are respectively the temperature detector, the raw material supplier, the water supplier, and the air in the first invention. It is an example of concrete implementation of a feeder.

  Next, specific operations of the fuel cell system in the present embodiment will be described.

  In the fuel cell system shown in FIG. 1, the raw material supplied from the raw material supply source is supplied to the first pump 3 through the raw material supply channel 4. The first pump 3 can change the flow rate of the source gas by the control unit 18 as will be described later. The raw material derived from the first pump 3 is supplied to the hydrogen generator 2 through the raw material supply channel 4. On the other hand, the water supplied from the water supply source is supplied to the third pump 14 through the water supply channel 15. The third pump 14 can change the flow rate of water by the control unit 18 as will be described later. The water led out from the third pump 14 is supplied to the hydrogen generator 2 through the water supply channel 15. Further, air supplied from a second pump 11 described later is also supplied to the selective oxidizer 10 of the hydrogen generator 2, and hydrogen-rich fuel gas is generated using the raw material gas, water, and air. The fuel gas derived from the hydrogen generator 2 is supplied to the fuel cell 1 The fuel gas supplied to the fuel cell 1 electrochemically reacts with oxygen in the air supplied to the fuel cell 1 (not shown). , Generate electricity. Although the hydrogen in the fuel gas is consumed by the power generation in the fuel cell 1, the fuel gas that has not been used for power generation is discharged from the fuel cell 1 as a residual fuel gas. The residual fuel gas discharged from the fuel cell 1 is discharged out of the system through the fuel gas discharge flow path 7. Further, air as an oxidant gas used for fuel gas generation is taken from the periphery of the second pump 11 by driving the second pump 11. The taken-in air is supplied to the selective oxidizer 10 of the hydrogen generator 2 through the air supply flow path 12 and is used for a chemical reaction with the raw material gas and water to generate a fuel gas.

  In order to supply raw material, water and air necessary for power generation to the hydrogen generator 2, the control unit 18 first calculates the flow rate of the necessary raw material gas according to the amount of power generated in the fuel cell 1, and the target flow rate of the raw material gas Set. Next, according to the set target flow rate of the source gas, the flow rates of water and air necessary for fuel gas generation in the hydrogen generator 2 are calculated, and the target flow rates of water and air are set. Further, the controller 18 controls the second pump 11 / the third pump 14 / according to the detected flow rates of the raw material, water, and air detected by the raw material flow meter 5, the water flow meter 16, and the air flow meter 13, respectively. Feedback control is performed to change the drive amount of the second pump 11.

  Next, an example of a specific operation relating to the first invention in the fuel cell system shown in the present embodiment will be described.

The controller 18 includes the second pump 11 / the third pump 14 / the second pump according to the detected flow rates of the raw material, the water flow meter 16, and the air flow meter 13, which are detected by the raw material flow meter 5, the water flow meter 16, and the air flow meter 13, respectively. Feedback control for changing the drive amount of the pump 11 is performed. At this time, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 is equal to or higher than the “first predetermined temperature (for example, 190 ° C.)”, the controller 18 supplies the raw material supplied to the hydrogen generator 2. The maximum flow rate of the second pump 11 is reset so that the driving amount of the second pump 11 is changed within the range. The first predetermined temperature is set lower than the limit temperature at which the methanation reaction occurs abruptly.

  With this configuration, since the power generation is not continued at the maximum flow rate of the raw material gas before the selective oxidation catalyst layer temperature of the selective oxidizer 10 exceeds the first predetermined temperature, the methanation reaction is prevented from abruptly occurring. can do. Further, since the controller 18 sets the target flow rate of air according to the reset raw material gas flow rate with a small maximum flow rate, the maximum flow rate of air supplied to the selective oxidizer 10 is also reduced. As a result, when the selective oxidation catalyst layer temperature becomes equal to or higher than the first predetermined temperature, the amount of heat generated in the selective oxidation reaction performed in the selective oxidizer 10 can be automatically reduced / suppressed. It is possible to prevent the catalyst layer temperature from rapidly rising and falling into a thermal runaway state where temperature control becomes impossible.

  The maximum flow rate of the raw material gas supplied to the hydrogen generator 2 is set according to at least one of the installation time of the fuel cell system, the cumulative power generation time, the cumulative number of start / stop times, and the cumulative combustion time. May be. By doing so, even if the selective oxidation treatment capacity of the selective oxidizer 10 of the hydrogen generator 2 decreases with time, even if the selective oxidation treatment amount with respect to the selective oxidation catalyst layer temperature decreases, thermal runaway is prevented. It becomes possible to do.

  Further, the first predetermined temperature set for controlling the maximum flow rate of the raw material supplied to the hydrogen generator 2 is the fuel cell system installation time, the cumulative power generation time, the cumulative start / stop count, and the cumulative combustion time. You may make it set with respect to at least any one of these. By doing so, even if the selective oxidation treatment capability of the selective oxidizer 10 of the hydrogen generator 2 decreases with time, even if the selective oxidation treatment capability with respect to the selective oxidation catalyst layer temperature decreases, thermal runaway is prevented. It becomes possible to do.

(Embodiment 2)
FIG. 2 is a block diagram showing the configuration of the fuel cell system according to Embodiment 2 of the present invention. In FIG. 2, the same components as those in FIG.

  In the present embodiment, in addition to the fuel cell power generation system described in the first embodiment, the DC power generated by the fuel cell 1 is converted into AC power, and the power is supplied to the power load 22 in conjunction with the system power 21. An inverter 23 and a power detector 24 that detects the amount of power supplied to the power load 22 are provided. And the controller 18 is AC power from the inverter 23 according to the electric energy which the electric power detector 24 detects in the range below the electric power generation lower limit (for example, 250W) and below the first electric power generation upper limit (for example, 750W). Is controlled to output.

  Next, an example of a specific operation related to the fourth invention and the fifth invention in the fuel cell power generation system in the present embodiment will be described using the power generation amount control flowchart shown in FIG.

First, the controller 18 performs control so that the upper limit of the output power amount from the inverter 23 is output as a first power generation amount upper limit value (for example, 750 W) (S101). The controller 18 determines whether the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 is higher or lower than a first predetermined temperature (for example, 190 ° C.) (S102), and first predetermined If it is lower than the temperature, the process returns to step S101. On the other hand, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 in step S102 is equal to or higher than the first predetermined temperature, the controller 18 sets the upper limit of the output power amount from the inverter 23 to the first value. Control is performed so as to output a second power generation amount upper limit value (for example, 700 W) smaller than the power generation amount upper limit value (for example, 750 W) (S103).
. The controller 18 further determines whether the selective oxidation catalyst layer temperature of the selective selective oxidizer 10 detected by the temperature sensor 17 is higher or lower than a second predetermined temperature (for example, 180 ° C.) (S104), and the second If the temperature exceeds the predetermined temperature, the process returns to step S103. On the other hand, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 in step S104 becomes lower than the second predetermined temperature, the controller 18 sets the upper limit of the output power amount from the inverter 23. Control is performed so as to output the power generation amount upper limit value of 1 (S105).

  With this configuration, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 becomes equal to or higher than the first predetermined temperature, the maximum power generation amount is reduced, so that the methanation reaction can be prevented from occurring rapidly. Further, since the controller 18 sets the target flow rates of the raw material gas, water, and air according to the reset power generation amount, the maximum flow rates of the raw material gas, water, and air supplied to the selective oxidizer 10 are also reduced. As a result, when the selective oxidation catalyst layer temperature becomes equal to or higher than the first predetermined temperature, the amount of heat generated in the selective oxidation reaction performed in the selective oxidizer 10 can be automatically reduced / suppressed. It is possible to prevent the catalyst layer temperature from rapidly rising and falling into a thermal runaway state where temperature control becomes impossible.

  Further, the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 when the control is performed so as to output the second power generation amount upper limit value (for example, 700 W) is lower than the second predetermined temperature. When it becomes, the controller 18 performs control to output the upper limit of the output power amount from the inverter 23 as the first power generation amount upper limit value. Thereby, while preventing the thermal runaway of the selective oxidizer 10, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 becomes lower than the second predetermined temperature, the upper limit of the output power amount is returned to the original and electric power is generated. be able to.

  The first predetermined temperature that is set to control the output power amount by setting the upper limit of the output power amount from the inverter 23 as a smaller second power generation amount upper limit value is the installation time of the fuel cell system, the accumulated power generation time. Further, it may be set for at least one of the cumulative start / stop count and the cumulative combustion time. By doing so, even if the selective oxidation treatment capability of the selective oxidizer 10 of the hydrogen generator 2 decreases with time, even if the selective oxidation treatment capability with respect to the selective oxidation catalyst layer temperature decreases, thermal runaway is prevented. It becomes possible to do.

  In addition, the second predetermined temperature set for returning the upper limit of the output power amount from the inverter 23 to the original first power generation amount upper limit value and controlling the output power amount is the installation time of the fuel cell system, It may be set for at least one of the cumulative power generation time, the cumulative number of start / stop times, and the cumulative combustion time. By doing so, even if the selective oxidation treatment capability of the selective oxidizer 10 of the hydrogen generator 2 decreases with time, even if the selective oxidation treatment capability with respect to the selective oxidation catalyst layer temperature decreases, thermal runaway is prevented. It becomes possible to do.

(Embodiment 3)
Next, regarding the fuel cell system according to Embodiment 3 of the present invention, an example of a specific operation will be described using the block diagram showing the configuration of the fuel cell system shown in FIG. 1 and the raw material flow rate control flowchart shown in FIG. explain.

First, the controller 18 controls to supply the upper limit of the raw material flow rate to the hydrogen generator 2 as a first raw material flow rate upper limit value (for example, 3.5 NLM) (S201). The controller 18 determines whether the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 is higher or lower than the first predetermined temperature (for example, 190 ° C.) (S202), and the first predetermined If it is lower than the temperature, the process returns to step S201. On the other hand, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 in step S202 is equal to or higher than the first predetermined temperature, the controller 18 sets the upper limit of the raw material flow rate to the hydrogen generator 2 to the first. Is controlled so as to be supplied as a second raw material flow rate upper limit value (for example, 3.0 NLM) that is smaller than the raw material flow rate upper limit value (for example, 3.5 NLM) (S2).
03). The controller 18 further determines whether the selective oxidation catalyst layer temperature of the selective oxidation oxidizer 10 detected by the temperature sensor 17 is higher or lower than the second predetermined temperature (for example, 180 ° C.) (S204). If the temperature is equal to or higher than the predetermined temperature, the process returns to step S203. On the other hand, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 in step S204 becomes lower than the second predetermined temperature, the controller 18 sets the upper limit of the raw material flow rate to the hydrogen generator 2. Control is performed so that the first raw material flow rate upper limit value is supplied (S205).

  With this configuration, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 is equal to or higher than the first predetermined temperature, the maximum flow rate is reduced, so that the methanation reaction can be prevented from occurring rapidly. Further, since the controller 18 sets the target flow rates of the source gas, water, and air according to the reset maximum flow rates, the maximum flow rates of the source gas, water, and air supplied to the selective oxidizer 10 are also reduced. As a result, when the selective oxidation catalyst layer temperature becomes equal to or higher than the first predetermined temperature, the amount of heat generated in the selective oxidation reaction performed in the selective oxidizer 10 can be automatically reduced / suppressed. It is possible to prevent the catalyst layer temperature from rapidly rising and falling into a thermal runaway state where temperature control becomes impossible.

  Furthermore, the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 when the control is performed so that the second raw material flow rate upper limit value (for example, 3.0 NLM) is supplied to the hydrogen generator 2. When the temperature is lower than the second predetermined temperature, the controller 18 can perform control so that the upper limit of the raw material flow rate to the hydrogen generator 2 is supplied as the first raw material flow rate upper limit value. Therefore, while preventing the thermal runaway of the selective oxidizer 10, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 becomes lower than the second predetermined temperature, power can be generated with the upper limit of the raw material flow rate restored. it can.

  The first predetermined temperature may be set for at least one of the fuel cell system installation time, the cumulative power generation time, the cumulative number of start / stop times, and the cumulative combustion time. By doing so, even if the selective oxidation treatment capacity of the selective oxidizer 10 of the hydrogen generator 2 decreases with time, even if the selective oxidation treatment amount with respect to the selective oxidation catalyst layer temperature decreases, thermal runaway is prevented. It becomes possible to do.

  In addition, the second predetermined temperature set for controlling the upper limit of the raw material flow rate to the hydrogen generator 2 to be returned to the original first raw material flow rate upper limit value and supplied to the hydrogen generator 2 is the fuel cell You may make it set with respect to at least any one of the installation time of a system, the cumulative power generation time, the cumulative number of start / stops, and the cumulative combustion time. By doing so, even if the selective oxidation treatment capability of the selective oxidizer 10 of the hydrogen generator 2 decreases with time, even if the selective oxidation treatment capability with respect to the selective oxidation catalyst layer temperature decreases, thermal runaway is prevented. It becomes possible to do.

(Embodiment 4)
Next, regarding the fuel cell system according to Embodiment 4 of the present invention, the fuel cell according to the present embodiment will be described using the block diagram showing the configuration of the fuel cell system shown in FIG. 1 and the air flow rate control flowchart shown in FIG. An example of a specific operation related to the second invention and the third invention in the fuel cell power generation system according to the present embodiment in the power generation system will be described. In addition to the controller 18 shown in the first embodiment, the controller 18 in the present embodiment further has a function of resetting the target flow rate of the raw material based on the air flow rate.

First, the controller 18 controls to supply the upper limit of the air flow rate to the hydrogen generator 2 as a first air flow rate upper limit value (for example, 1.2 NLM) (S301). The controller 18 determines whether the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 is higher or lower than a first predetermined temperature (for example, 190 ° C.) (S302), and first predetermined If it is lower than the temperature, the process returns to step S301. On the other hand, if the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 in step S302 is equal to or higher than the first predetermined temperature, the controller 18 sets the upper limit of the air flow rate to the hydrogen generator 2 to the first. Is supplied as a second air flow rate upper limit value (for example, 1.0 NLM) smaller than the air flow rate upper limit value (for example, 1.2 NLM), and control is performed so as to reset the target flow rate of the raw material based on the air flow rate. (S303). The controller 18 further determines whether the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 is higher or lower than a second predetermined temperature (for example, 180 ° C.) (S304), and the second If the temperature exceeds the predetermined temperature, the process returns to step S303. On the other hand, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 in step S304 becomes lower than the second predetermined temperature, the controller 18 sets the upper limit of the air flow rate to the hydrogen generator 2. Control is performed so that the first air flow rate upper limit value is supplied (S305).

  With this configuration, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 becomes equal to or higher than the first predetermined temperature, the upper limit of the air flow rate is reduced, so that the methanation reaction can be prevented from occurring rapidly. Further, since the controller 18 sets the target flow rates of the source gas and water according to the reset air flow rate, the maximum flow rates of the source gas and water supplied to the selective oxidizer 10 are also reduced. As a result, when the selective oxidation catalyst layer temperature becomes equal to or higher than the first predetermined temperature, the amount of heat generated in the selective oxidation reaction performed in the selective oxidizer 10 can be automatically reduced / suppressed. It is possible to prevent the catalyst layer temperature from rapidly rising and falling into a thermal runaway state where temperature control becomes impossible.

  Furthermore, the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 when the control is performed so that the second air flow rate upper limit value (for example, 3.0 NLM) is supplied to the hydrogen generator 2. When the temperature becomes lower than the second predetermined temperature, the controller 18 can perform control so as to supply the upper limit of the air flow rate to the hydrogen generator 2 as the first air flow rate upper limit value. Therefore, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 becomes lower than the second predetermined temperature while preventing the thermal runaway of the selective oxidizer 10, electric power can be generated with the upper limit of the air flow rate restored. it can.

  The first predetermined temperature may be set for at least one of the fuel cell system installation time, the cumulative power generation time, the cumulative number of start / stop times, and the cumulative combustion time. By doing so, even if the selective oxidation treatment capability of the selective oxidizer 10 of the hydrogen generator 2 decreases with time, even if the selective oxidation treatment capability with respect to the selective oxidation catalyst layer temperature decreases, thermal runaway is prevented. It becomes possible to do.

  The second predetermined temperature may be set for at least one of the installation time of the fuel cell system, the cumulative power generation time, the cumulative number of start / stop times, and the cumulative combustion time. By doing so, even if the selective oxidation treatment capability of the selective oxidizer 10 of the hydrogen generator 2 decreases with time, even if the selective oxidation treatment capability with respect to the selective oxidation catalyst layer temperature decreases, thermal runaway is prevented. It becomes possible to do.

(Embodiment 5)
Next, regarding the fuel cell system according to Embodiment 5 of the present invention, the fuel cell according to the present embodiment will be described with reference to the block diagram showing the configuration of the fuel cell system shown in FIG. 1 and the water flow rate control flowchart shown in FIG. An example of a specific operation related to the eighth invention and the ninth invention in the power generation system will be described. In addition to the controller 18 shown in the first embodiment, the controller 18 in the present embodiment further has a function of resetting the target flow rate of the raw material based on the water flow rate.

First, the controller 18 controls to supply the upper limit of the water flow rate to the hydrogen generator 2 as a first water flow rate upper limit value (for example, 9.0 CCM) (S401). The controller 18 detects that the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 is a first predetermined temperature (for example, 190).
Whether the temperature is higher or lower than (° C.) is determined (S402). If the temperature is lower than the first predetermined temperature, the process returns to step S401. On the other hand, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 in step S402 is equal to or higher than the first predetermined temperature, the controller 18 sets the upper limit of the water flow rate to the hydrogen generator 2 to the first. Is supplied as a second water flow rate upper limit value (for example, 8.0 CCM) smaller than the water flow rate upper limit value (for example, 9.0 CCM), and control is performed so as to reset the target flow rate of the raw material based on the water flow rate. (S403). The controller 18 further determines whether the selective oxidation catalyst layer temperature of the selective selective oxidizer 10 detected by the temperature sensor 17 is higher or lower than a second predetermined temperature (for example, 180 ° C.) (S404), and the second If the temperature is equal to or higher than the predetermined temperature, the process returns to step S403. On the other hand, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 in step S404 becomes lower than the second predetermined temperature, the controller 18 sets the upper limit of the water flow rate to the hydrogen generator 2. Control is performed so as to supply the first water flow rate upper limit value (S405).

  With this configuration, when the selective oxidation catalyst layer temperature of the selective oxidizer 10 becomes equal to or higher than the first predetermined temperature, the upper limit of the water flow rate is reduced, so that the methanation reaction can be prevented from occurring rapidly. Further, since the controller 18 sets the target flow rates of the source gas and air in accordance with the reset water flow rate, the maximum flow rates of the source gas and air supplied to the selective oxidizer 10 are also reduced. As a result, when the selective oxidation catalyst layer temperature becomes equal to or higher than the first predetermined temperature, the amount of heat generated in the selective oxidation reaction performed in the selective oxidizer 10 can be automatically reduced / suppressed. It is possible to prevent the catalyst layer temperature from rapidly rising and falling into a thermal runaway state where temperature control becomes impossible.

  Furthermore, the selective oxidation catalyst layer temperature of the selective oxidizer 10 detected by the temperature sensor 17 when the control is performed so that the second water flow rate upper limit value (for example, 8.0 CCM) is supplied to the hydrogen generator 2. When the temperature is lower than the second predetermined temperature, the upper limit of the water flow rate can be restored to generate power.

  Note that the first predetermined temperature set for controlling the upper limit of the water flow rate to the hydrogen generator 2 to be supplied to the hydrogen generator 2 as a smaller second water flow rate upper limit value is the fuel cell system installation It may be set for at least one of time, accumulated power generation time, accumulated start / stop count, and accumulated combustion time. By doing so, even if the selective oxidation treatment capability of the selective oxidizer 10 of the hydrogen generator 2 decreases with time, even if the selective oxidation treatment capability with respect to the selective oxidation catalyst layer temperature decreases, thermal runaway is prevented. It becomes possible to do.

  Further, the second predetermined temperature set for controlling the upper limit of the water flow rate to the hydrogen generator 2 to be returned to the original first water flow rate upper limit value and supplied to the hydrogen generator 2 is the fuel cell You may make it set with respect to at least any one of the installation time of a system, the cumulative power generation time, the cumulative number of start / stops, and the cumulative combustion time. By doing so, even if the selective oxidation treatment capability of the selective oxidizer 10 of the hydrogen generator 2 decreases with time, even if the selective oxidation treatment capability with respect to the selective oxidation catalyst layer temperature decreases, thermal runaway is prevented. It becomes possible to do.

  As described above, since the fuel cell system according to the present invention can reduce the amount of heat generated by oxidation in the selective oxidizer, it is possible to prevent thermal runaway, so at least a hydrogen generator having a selective oxidizer. It is useful for a fuel cell system equipped with Further, the present invention can be applied to uses such as a hydrogen station that generates hydrogen using a hydrogen generator having at least a selective oxidizer.

DESCRIPTION OF SYMBOLS 1 Fuel cell 2,101 Hydrogen generator 3 1st pump 4 Raw material supply flow path 5 Raw material flow meter 6 Fuel gas supply flow path 7 Fuel gas discharge flow path 8,124 Reformer 9,125 Transformer 10,126 selection Oxidizer 11 Second pump 12 Air supply flow path 13 Air flow meter 14 Third pump 15 Water supply flow path 16 Water flow meter 17 Temperature sensor 18 Control unit 21 System power 22 Power load 23 Inverter 24 Power detector 123 Desulfurization vessel

Claims (9)

A fuel cell that generates power using fuel gas and air;
A hydrogen generator that includes at least a selective oxidizer and generates a fuel gas containing hydrogen using raw material, water, and air;
A temperature detector for detecting the temperature of the selective oxidizer;
A raw material supplier for supplying raw material to the hydrogen generator;
A water supply for supplying water to the hydrogen generator;
An air supply for supplying air to the selective oxidizer;
A controller for controlling the fuel cell, the raw material supplier, the water supplier and the air supplier;
With
When the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature, the controller supplies the raw material supplied to the hydrogen generator as compared to before the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature. A fuel cell system that controls the maximum flow rate of the fuel cell to be small.   The controller controls the flow rate of the raw material supplied to the hydrogen generator to be in a range not less than the raw material flow rate lower limit value and not more than the first raw material flow rate upper limit value, and the temperature of the selective oxidizer is the first 2. The fuel cell system according to claim 1, wherein when the temperature is equal to or higher than a predetermined temperature, the flow rate of the raw material is controlled to be equal to or lower than a second raw material flow rate upper limit value smaller than the first raw material flow rate upper limit value.   When the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature and then becomes lower than the second predetermined temperature, the controller sets the flow rate of the raw material to the first raw material flow rate upper limit value. The fuel cell system according to claim 2, which is controlled as follows.   The controller controls an output power amount generated by the fuel cell to be in a range not less than a power generation amount lower limit value and not more than a first power generation amount upper limit value, and the temperature of the selective oxidizer is a first predetermined value. 2. The fuel cell system according to claim 1, wherein when the temperature is equal to or higher than a temperature, the output power amount is controlled to be equal to or lower than a second power generation amount upper limit value that is smaller than the first power generation amount upper limit value.   When the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature and then becomes lower than the second predetermined temperature, the controller reduces the output power amount to the first power generation upper limit value or less. The fuel cell system according to claim 4, which is controlled.   The controller controls the flow rate of the air supplied to the hydrogen generator to be in a range not less than an air flow rate lower limit value and not more than a first air flow rate upper limit value, and the temperature of the selective oxidizer is a first value. When the temperature is higher than a predetermined temperature, the flow rate of the air is controlled to be equal to or lower than a second air flow rate upper limit value smaller than the first air flow rate upper limit value, and the target of the raw material is reset using the air flow rate. The fuel cell system according to claim 1, wherein the flow rate of the raw material is controlled based on the flow rate.   The controller is configured such that when the temperature of the selective oxidizer becomes equal to or higher than the first predetermined temperature and then becomes lower than the second predetermined temperature, the air flow rate is the first selected air flow upper limit value. The fuel cell system according to claim 6, which is controlled as follows.   The controller controls the flow rate of water supplied to the hydrogen generator to be in a range not less than a water flow rate lower limit value and not more than a first water flow rate upper limit value, and the temperature of the selective oxidizer is a first value. When the temperature is equal to or higher than a predetermined temperature, the flow rate of the water is controlled to be equal to or lower than a second water flow rate upper limit value smaller than the first water flow rate upper limit value, and the target of the raw material is reset using the water flow rate. The fuel cell system according to claim 1, wherein the flow rate of the raw material is controlled based on the flow rate. The controller is configured such that when the temperature of the selective oxidizer becomes equal to or higher than a first predetermined temperature and then becomes lower than a second predetermined temperature, the flow rate of the water is the first water flow rate upper limit value. The fuel cell system according to claim 8, which is controlled as follows.

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