JP2020031007A - Fuel cell system - Google Patents

Abstract

To inhibit occurrence of coking at a reformer, water immersion of a fuel cell stack, acceleration of oxidation degradation of an anode at the time of a system stop.SOLUTION: When a vaporizer's temperature detected by a vaporizer temperature sensor reaches a temperature lower than a second threshold in the case that a temperature detected by a temperature detector is equal to or higher than a first threshold at the time of system stop, abnormal time stop processing for controlling a raw material gas supply device, a reforming water supply device, and an oxidant gas supply device so that all of raw material gas supply from the raw material gas supply device, supply of reforming water from the reforming water supply device, and supply of oxidant gas from the oxidant gas supply device are stopped is executed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel cell system.

  Conventionally, this type of fuel cell system includes a fuel cell stack that generates electric power based on a hydrogen-containing gas supplied to an anode and an oxidizing gas (air) supplied to a cathode, and a hydrocarbon gas formed by evaporating water. And a reformer for reforming the hydrocarbon gas from the vaporizer into a hydrogen-containing gas and supplying it to the anode, a fuel pump for supplying the hydrocarbon gas to the vaporizer, and a vaporizer. A water supply pump for supplying water, an air pump for supplying oxidant gas to the cathode, a heating burner for receiving air and fuel gas to heat the fuel cell stack, a fuel cell stack and a carburetor There has been proposed a device having a heat-insulating container for accommodating a reformer and a gas burner (for example, see Patent Document 1). In this fuel cell system, when the system is stopped, the supply amount of the hydrocarbon gas supplied to the fuel cell stack is reduced while supplying the oxidizing gas to the fuel cell stack and supplying only air to the heating burner. . When the temperature of the reformer drops to 200 ° C. to 550 ° C., the supply of the hydrocarbon gas is stopped, and when the temperature of the vaporizer reaches 100 ° C. while the supply of steam is continued, a certain amount of gas is supplied to the vaporizer. After supplying water, stop supplying water.

JP 2010-80192 A

  In the above-described fuel cell system, when the system is stopped, for example, when the temperature in the heat insulating container is not uniform, the temperature of the vaporizer may drop sharply compared to the temperature of the fuel cell stack or the reformer. . In this case, it is difficult to generate steam in the vaporizer, and there is a concern that caulking (fuel carbonization phenomenon) occurs in the reformer or the fuel cell stack is flooded. In addition, when the supply of water is stopped after supplying a certain amount of water to the vaporizer as in the above-described fuel cell system, the progress of the endothermic reaction in the vaporizer further hinders the generation of steam, and the reforming is performed. Coking in the vessel and flooding of the fuel cell stack are likely to occur. In order to suppress coking in the reformer and flooding of the fuel cell stack, it is conceivable to stop the supply of hydrocarbon gas when the temperature of the vaporizer suddenly drops, but if the temperature of the fuel cell stack is high, In addition, there is a concern that the anode is exposed to an oxygen atmosphere at a high temperature, thereby promoting the oxidative deterioration of the anode.

  A main object of the fuel cell system of the present invention is to suppress coking in a reformer, flooding of a fuel cell stack, and promotion of oxidative deterioration of an anode when the system is stopped.

  The fuel cell system of the present invention employs the following means to achieve the above-described main object.

The fuel cell system of the present invention comprises:
A fuel cell that generates power based on the fuel gas supplied to the anode and the oxidant gas supplied to the cathode,
A vaporizer for evaporating the reformed water to produce steam,
A reformer that reforms the mixed gas of the steam and the raw material gas into the fuel gas and supplies the fuel gas to the anode;
A combustion unit that heats the vaporizer and the reformer by burning off-gas that has passed through the fuel cell,
A source gas supply device for supplying the source gas to the reformer,
A reforming water supply device for supplying the reforming water to the vaporizer,
An oxidizing gas supply device that supplies the oxidizing gas to the cathode,
A vaporizer temperature sensor that is provided in a fuel cell module having the fuel cell, the vaporizer, the reformer, and the combustion unit, and detects a temperature of the vaporizer;
A temperature detector provided at a position different from the vaporizer temperature sensor in the fuel cell module;
When the system is stopped, when the temperature detected by the temperature detector falls below a first threshold, the source gas supply device is controlled such that the supply of the source gas from the source gas supply device is stopped. Together with or after controlling the reforming water supply device so that the supply of the reforming water from the reforming water supply device is stopped, and thereafter, the oxidizing gas from the oxidizing gas supply device is controlled. A control device that executes a normal stop process for controlling the oxidizing gas supply device so that the supply of the gas is stopped,
A fuel cell stem comprising:
The control device is configured such that, when the system is stopped, the temperature of the vaporizer detected by the vaporizer temperature sensor when the temperature detected by the temperature detector is equal to or higher than the first threshold is lower than a second threshold. At this time, the supply of the source gas from the source gas supply device, the supply of the reforming water from the reforming water supply device, and the supply of the oxidizing gas from the oxidizing gas supply device all stop. Executing an abnormal time stop process for controlling the raw material gas supply device, the reformed water supply device, and the oxidizing gas supply device so that
That is the gist.

  In the fuel cell system of the present invention, when the system is stopped, the supply of the source gas from the source gas supply device is stopped when the temperature detected by the temperature detector falls below the first threshold. Controlling or controlling the supply device, then controlling the reformed water supply device so that the supply of the reformed water from the reformed water supply device is stopped, and then controlling the oxidizing gas from the oxidizing gas supply device. A normal stop process for controlling the oxidizing gas supply device so as to stop the supply of oxygen is performed. Then, when the system is stopped, when the temperature detected by the temperature detector is equal to or higher than the first threshold and the temperature of the vaporizer detected by the vaporizer temperature sensor is lower than the second threshold, the raw material from the raw material gas supply device is The raw material gas supply device, the reformed water supply device, and the oxidant such that the gas supply, the supply of the reformed water from the reformed water supply device, and the supply of the oxidant gas from the oxidant gas supply device are all stopped. An abnormal time stop process for controlling the gas supply device is executed. This makes it possible to suppress coking in the reformer and water intrusion of the fuel cell stack, and to suppress the anode from being exposed to an oxygen atmosphere at a high temperature, thereby suppressing the promotion of oxidative deterioration of the anode. .

  In such a fuel cell system of the present invention, when the system is stopped by the abnormal stop processing, the control device prohibits a user from instructing the next start of the system, stores a system abnormality, and reports a system abnormality. And at least one of contacting the service center. By doing so, it is possible to prevent secondary failure, improve safety, and improve the workability of maintenance by the service center operator.

  In the fuel cell system of the present invention, the temperature detector includes a battery temperature sensor for detecting a temperature of the fuel cell, a reformer temperature sensor for detecting a temperature of the reformer, and a combustion for detecting a temperature of the combustion unit. The temperature sensor may include at least one of the unit temperature sensors. Here, when the temperature detector has the battery temperature sensor and the reformer temperature sensor, the control device detects the temperature of the fuel cell detected by the battery temperature sensor and the temperature of the fuel cell detected by the reformer temperature sensor. The temperature detected by the temperature detector may be determined to be less than the first threshold when the temperature of the reformer is lower than the respective threshold. Further, when the temperature detector has the battery temperature sensor and the combustion unit temperature sensor, the control device is configured to detect the temperature of the fuel cell detected by the battery temperature sensor and the temperature of the fuel cell detected by the combustion unit temperature sensor. When the temperature of the combustion section falls below the respective thresholds, it may be determined that the temperature detected by the temperature detector has fallen below the first threshold.

FIG. 1 is a configuration diagram illustrating a schematic configuration of a fuel cell system 10 according to an embodiment. 9 is a flowchart illustrating an example of a stop control routine executed by a CPU 81 of the control device 80. FIG. 5 is an explanatory diagram showing an example of a state of a time change of a combustion section temperature Tc, a stack temperature Ts, and a carburetor temperature Tv when the system is stopped. 9 is a flowchart illustrating an example of a stop control routine according to a modification.

  Next, an embodiment for carrying out the present invention will be described.

  FIG. 1 is a configuration diagram schematically illustrating the configuration of a fuel cell system 10 according to the present embodiment. As shown in FIG. 1, the fuel cell system 10 according to the present embodiment includes a power generation unit 20 having a fuel cell stack 36 that receives a supply of a fuel gas containing hydrogen and an oxidant gas (air) containing oxygen to generate power. A hot water supply unit 100 having a hot water storage tank 101 for recovering and supplying hot water generated by the power generation of the power generation unit 20, and a control device 80 for controlling the entire system.

  The power generation unit 20 includes a fuel cell module 30 including a vaporizer 32, a reformer 33, and a fuel cell stack 36, a source gas supply device 40 that supplies a source gas (for example, natural gas or LP gas) to the vaporizer 32, An air supply device 50 for supplying air to the fuel cell stack 36, a reformed water supply device 55 for supplying reformed water to the vaporizer 32, and an exhaust heat recovery device 60 for recovering exhaust heat generated in the fuel cell module 30 And. These are housed in the housing 22. The casing 22 is provided with an intake port 22a and an exhaust port 22b, and a ventilation fan 24 for taking in outside air and ventilating the inside of the casing 22 is provided near the intake port 22a.

  The vaporizer 32 evaporates the reformed water from the reformed water supply device 55 to generate steam and preheats the raw material gas from the raw material gas supply device 40. The reformer 33 is configured by supporting a reforming catalyst (for example, a Ru or Ni-based catalyst) on a carrier such as a ceramic, and steam reforming a mixed gas of the raw material gas and the steam supplied from the vaporizer 32. It is reformed into fuel gas (reformed gas) by the reaction. Near the inlet of the reformer 33, a temperature sensor 91 for detecting the temperature of the vaporizer 32 (vaporizer temperature Tv) is provided.

  The vaporizer 32, the reformer 33, and the fuel cell stack 36 are housed in a box-shaped module case 31 formed of a heat insulating material. In the module case 31, a combustion section 34 for supplying heat necessary for starting the fuel cell stack 36, generating steam in the vaporizer 32, and performing a steam reforming reaction in the reformer 33 is provided. A fuel off-gas (anode off-gas) and an oxidant off-gas (cathode off-gas) that have passed through the fuel cell stack 36 are supplied to the combustion unit 34, and the mixed gas is ignited by an ignition heater 35 and burned, thereby burning the fuel cell. The stack 36, the vaporizer 32, and the reformer 33 are heated. The combustion section 34 is provided with a temperature sensor 92 for detecting the temperature of the combustion section 34. The combustion exhaust gas generated by the combustion of the fuel off-gas and the oxidant off-gas is supplied to the heat exchanger 62 via the combustion catalyst 37. The combustion catalyst 37 is an oxidation catalyst that reburns the fuel gas remaining in the combustion section 34 with the catalyst.

  The exhaust heat recovery device 60 includes a circulation pipe 61 that connects a heat exchanger 62 to which combustion exhaust gas is supplied from the fuel cell module 30 and a hot water storage tank 101 that stores hot water to form a circulation path of the hot water. The circulation pipe 61 is provided with a circulation pump 63. By driving the circulation pump 63, the hot water is heated by heat exchange between the hot water and the combustion exhaust gas in the heat exchanger 62, and the hot water is heated. Water is stored in hot water storage tank 101. The heat exchanger 62 is connected to the reforming water tank 57 via a condensed water supply pipe 66 and to the outside air via an exhaust gas discharge pipe 67. The combustion exhaust gas supplied to the heat exchanger 62 is condensed with a steam component by heat exchange with the hot water, and the condensed water (condensed water) is purified by a water purifier (not shown) and collected in the reformed water tank 57. Is done. Further, the remaining exhaust gas (gas component) is exhausted to the outside air via an exhaust gas exhaust pipe 67.

  The source gas supply device 40 has a source gas supply pipe 41 that connects the gas supply source 1 and the vaporizer 32. The source gas supply pipe 41 is provided with source gas supply valves (electromagnetic valves) 42 and 43, an orifice 44, a source gas pump 45, and a desulfurizer 46 in this order from the gas supply source 1 side. By driving the source gas pump 45 with the valve 43 opened, the source gas from the gas supply source 1 is supplied to the vaporizer 32 through the desulfurizer 46. The raw material gas supplied to the vaporizer 32 is supplied to the reformer 33 via the vaporizer 32 and is reformed into a fuel gas. The source gas supply valves 42 and 43 are double valves connected in series. The desulfurizer 46 is for removing sulfur contained in the raw material gas. For example, a normal temperature desulfurization method in which a sulfur compound is adsorbed on an adsorbent such as zeolite and removed can be employed. In addition, the desulfurization method is not limited to the normal temperature desulfurization method, and various methods can be adopted. A pressure sensor 47 for detecting the pressure of the source gas in the source gas supply pipe 41 is provided between the source gas supply valve 43 and the orifice 44 of the source gas supply pipe 41. Between them, a flow rate sensor 48 for detecting a flow rate (gas flow rate Fg) of the raw material gas flowing through the raw material gas supply pipe 41 per unit time is provided.

  The air supply device 50 has an air supply pipe 51 that connects the filter 52 communicating with the outside air and the fuel cell stack 36. The air supply pipe 51 is provided with an air blower 53. By driving the air blower 53, the air sucked through the filter 52 is supplied to the fuel cell stack 36. The air supply pipe 51 is provided, downstream of the air blower 53, with a flow rate sensor 54 for detecting a flow rate of air flowing through the air supply pipe 51 per unit time (air flow rate Fa).

  The reformed water supply device 55 has a reformed water supply pipe 56 that connects the reformed water tank 57 that stores the reformed water and the vaporizer 32. The reforming water supply pipe 56 is provided with a reforming water pump 58. By driving the reforming water pump 58, the reforming water in the reforming water tank 57 is supplied to the vaporizer 32. The reforming water supplied to the vaporizer 32 is converted into steam in the vaporizer 32 and used for a steam reforming reaction in the reformer 33. The reformed water tank 57 is provided with a water purifier (not shown) for purifying the stored reformed water.

  The fuel cell stack 36 includes a solid oxide fuel cell including a solid electrolyte made of an oxygen ion conductor, an anode provided on one surface of the solid electrolyte, and a cathode provided on the other surface of the solid electrolyte. They are stacked. The fuel cell stack 36 generates power by an electrochemical reaction between hydrogen in the fuel gas supplied to the anode and oxygen in the air supplied to the cathode. A temperature sensor 93 that detects the temperature of the fuel cell stack 36 (stack temperature Ts) is provided near or inside the fuel cell stack 36. The power line 3 from the commercial power supply 2 to the load 4 is connected to the output terminal of the fuel cell stack 36 via the power conditioner 70.

  The power conditioner 70 is capable of connecting a DC / DC converter that boosts a DC voltage output from the fuel cell stack 36 to a predetermined voltage (for example, DC 250 V to 300 V), and interconnects the boosted DC voltage with the commercial power system 2. It has an inverter for converting to an AC voltage (for example, AC200V). A power supply board 78 is connected to a power line branched from the power conditioner 70. The power supply board 78 converts a DC voltage output from the fuel cell stack 36 or an AC voltage from the commercial power system 2 into a DC voltage suitable for the operation of the accessories and supplies the DC voltage to the accessories. In the embodiment, the auxiliary equipment includes source gas supply valves 42 and 43, a source gas pump 45, an air blower 53, a reforming water pump 58, a circulation pump 63, and the like.

  The control device 80 is configured as a microprocessor with a CPU 81 at the center. In addition to the CPU 81, a ROM 82 for storing a processing program, a RAM 83 for temporarily storing data, and a non-volatile EEPROM 84 for storing and holding data. , A timer (not shown) for measuring time, and an input / output port (not shown). Various detection signals from the pressure sensor 47, the flow sensors 48 and 54, the temperature sensors 91 to 93, and the like are input to the control device 80 via input ports. In addition, the control device 80 sends a drive signal to the fan motor of the ventilation fan 24, a drive signal to the solenoids of the source gas supply valves 42 and 43, a drive signal to the pump motor of the source gas pump 45, and a drive signal of the air blower 53 to the blower motor. Drive signal, drive signal to the pump motor of the reforming water pump 58, drive signal to the pump motor of the circulation pump 63, control signal to the power conditioner 70 (DC / DC converter or inverter), control to the power supply board 78 A signal, a drive signal to the ignition heater 35, a display control signal to a display panel 90 for displaying various information, and the like are output via an output port.

  In the fuel cell system 10 configured as described above, a system request value (system request output) based on the request output required by the load 4 is input, and the target stack current Iout * of the fuel cell stack 36 is calculated based on the input system request value. The power generation control for controlling the raw material gas supply device 40, the reformed water supply device 55, and the air supply device 50 according to the set target stack current Iout * is executed. More specifically, the control of the source gas supply device 40 is performed by setting a target gas flow rate Fg * to be supplied by the source gas supply device 40 based on the target stack current Iout *, and using the target gas flow rate Fg * and the flow rate sensor 48. The duty Dg is set by feedback control based on a deviation from the detected gas flow rate Fg, and the pump motor of the raw material gas pump 45 is controlled based on the set duty Dg. The control of the reforming water supply device 55 is such that the steam carbon ratio (S / C), which is the ratio of the flow rate of steam per unit time to the flow rate of the raw material gas supplied to the reformer 33, is set to The target reforming water flow rate Fw * is set so as to have a predetermined ratio predetermined according to the type, the duty Dw is set based on the set target reforming water flow rate Fw *, and based on the set duty Dw. This is performed by controlling the pump motor of the reforming water pump 58. The air supply device 50 is controlled by setting a target air flow rate Fa * to be supplied by the air supply device 50 so as to have a predetermined ratio (air-fuel ratio) with respect to a target gas flow rate Fg * of the raw material gas, and setting the target value. This is performed by setting the duty Da by feedback control based on the difference between the air flow rate Fa * and the air flow rate Fa detected by the flow rate sensor 54, and controlling the blower motor of the air blower 53 based on the set duty Da.

  In addition, in the fuel cell system 10, when the system is started, the corresponding accessories are sequentially controlled to adsorb the fuel component to the desulfurizer 46 to suppress the air-fuel ratio deviation of the mixed gas. The purging process of the unit 34, the off-gas ignition process in the combustion unit 34, the steam reforming process, and the like are executed. When the fuel cell system 10 is started by executing these processes, power generation by the fuel cell stack 36 and hot water supply by the hot water supply unit 100 become possible. Note that the above-described activation processing is merely an example, and some processing may be omitted depending on the configuration of the fuel cell system 10, the state of accessories, and the like.

  Next, an operation when the system is stopped in the fuel cell system 10 will be described. FIG. 2 is a flowchart illustrating an example of a stop control routine executed by the CPU 81 of the control device 80. This routine is executed when an instruction to stop the system is issued.

  When the stop control routine of FIG. 2 is executed, the CPU 81 of the control device 80 changes the source gas from the source gas supply device 40 and the reformed water supply device 55 to the source gas in order to stop the power generation in the fuel cell stack 36. The source gas pump 45 and the reforming water pump 58 are controlled so that a small amount of high quality water is supplied, and the air blower 53 is supplied with the maximum amount of air from the air supply device 50 to cool the fuel cell stack 36. Control is performed to start the system stop processing (step S100). When the anode of the fuel cell stack 36 is exposed to an oxygen atmosphere at a high temperature, the anode is oxidized, and the power generation performance is reduced. For this reason, when the system is stopped, the source gas supply device 40 and the reforming water supply device 55 need to supply the fuel gas to the anode until the fuel cell stack 36 is sufficiently cooled. It supplies a minimum of raw material gas and reforming water.

  Subsequently, the carburetor temperature Tv from the temperature sensor 91, the combustion section temperature Tc from the temperature sensor 92, and the stack temperature Ts from the temperature sensor 93 are input (Step S110), and the input combustion section temperature Tc is compared with a threshold value Tcref1. At the same time (step S120), the stack temperature Ts is compared with a threshold value Tsref1 (step S130). Here, the threshold value Tcref1 and the threshold value Tsref1 are threshold values used to determine whether or not the combustion section temperature Tc and the stack temperature Ts have decreased to a temperature at which the anode of the fuel cell stack 36 is not easily oxidized. For example, 310 ° C., 320 ° C., 330 ° C., or the like is used, and as the threshold Tsref, for example, 240 ° C., 250 ° C., 260 ° C., or the like is used.

  When the combustion section temperature Tc is equal to or higher than the threshold value Tcref1 in step S120 or when the stack temperature Ts is equal to or higher than the threshold value Tsref1 in step S130, the carburetor temperature Tv is compared with the threshold value Tvref (step S140), and the carburetor temperature Tv is equal to or higher than the threshold value Tvref. In the case of, the process returns to step S110. Here, the threshold value Tvref is a threshold value used to determine whether or not the vaporizer temperature Tv has decreased to a temperature at which steam is not easily generated in the vaporizer 32, and is, for example, 105 ° C., 110 ° C., or 115 ° C. Is used.

  FIG. 3 is an explanatory diagram showing an example of how the combustion section temperature Tc, the stack temperature Ts, and the carburetor temperature Tv change over time when the system is stopped. When the system is stopped, basically, as shown in FIG. 3A, the combustion section temperature Tc, the stack temperature Ts, and the carburetor temperature Tv decrease in the same tendency, and are not shown. When the vaporizer temperature Tv is equal to or higher than the threshold Tvref, the combustion section temperature Tc is lower than the threshold Tcref1, and the stack temperature Ts is lower than the threshold Tsref1. However, as shown in FIG. 3 (B), the vaporizer temperature Tv becomes lower than the combustion section temperature Tc and the stack temperature Ts due to the supply of excess reforming water (inhibition of the generation of steam due to the progress of the endothermic reaction) and the like. There is a case where the temperature of the carburetor Tv suddenly decreases and reaches a value lower than the threshold value Tvref when the combustion portion temperature Tc is equal to or higher than the threshold value Tcref1 or when the stack temperature Ts is equal to or higher than the threshold value Tsref1. The process of steps S110 to S140 is a process of determining whether the operation is normal as shown in FIG. 3A or abnormal as shown in FIG. When the temperature in the fuel cell module 30 (module case 31) is not uniform when the system is stopped, for example, when the system is stopped or immediately after power generation in the fuel cell stack 36 is started, the system shown in FIG. It is likely to be abnormal at the time as shown in FIG.

  When the combustion section temperature Tc is less than the threshold value Tcref1 in step S120 and the stack temperature Ts is less than the threshold value Tsref1 in step S130 while the processing of steps S110 to S140 is being repeatedly executed, as shown in FIG. It is determined that the operation is normal, and a normal stop process is executed (steps S150 to S190), and the present routine ends (the system stop process ends).

  In the normal stop processing, first, the raw material gas pump 45 and the reformed water pump 58 are operated so that the supply of the raw material gas from the raw material gas supply device 40 and the supply of the reformed water from the reformed water supply device 55 are stopped. Is controlled (step S150). At this time, the maximum supply of air from the air supply device 50 is continued to continuously cool the fuel cell stack 36.

  Subsequently, the combustion unit temperature Tc from the temperature sensor 92 and the stack temperature Ts from the temperature sensor 93 are input (step S160), and the input combustion unit temperature Tc is compared with a threshold Tcref2 lower than the threshold Tcref1 (step S170). ), The stack temperature Ts is compared with a threshold Tsref2 lower than the threshold Tsref1 (Step S180). Here, the threshold value Tcref2 and the threshold value Tsref2 are threshold values used to determine whether or not the supply of air from the air supply device 50 may be stopped. For example, 140 ° C., 150 ° C., 160 ° C., etc. Used.

  When the combustion section temperature Tc is equal to or higher than the threshold value Tcref2 in Step S170, or when the stack temperature Ts is equal to or higher than the threshold value Tsref2 in Step S180, the process returns to Step S160. In this way, the processing of steps S160 to S180 is repeatedly executed, and when the combustion section temperature Tc is less than the threshold value Tcref2 in step S170 and the stack temperature Ts is less than the threshold value Tsref2 in step S180, the supply of air from the air supply device 50 is stopped. The air blower 53 is controlled to be stopped (step S190), and the normal stop processing ends.

  When the carburetor temperature Tv falls below the threshold value Tvref in step S140 during the repetitive execution of the processing in steps S110 to S140, it is determined that an abnormal state as shown in FIG. As the processing, the source gas pump 45 is controlled so that the supply of the source gas from the source gas supply device 40, the supply of the reforming water from the reforming water supply device 55, and the supply of the air from the air supply device 50 are all stopped. , The reforming water pump 58 and the air blower 53 are controlled (step S200), and this routine ends. In the embodiment, the abnormal stop processing is processing for shutting down the system, and in addition to these, other auxiliary equipment (for example, the raw material gas supply valves 42 and 43 and the circulation pump 63) are also stopped.

  If the vaporizer temperature Tv falls below the threshold value Tvref when the combustion section temperature Tc is equal to or higher than the threshold value Tcref1 or when the stack temperature Ts is equal to or higher than the threshold value Tsref1, it becomes difficult for the vaporizer 32 to generate sufficient steam, and the reformer 33 There is a fear that the steam supplied to the fuel cell is insufficient, and caulking (fuel carbonization phenomenon) occurs in the reformer 33 or the fuel cell stack 36 is flooded. On the other hand, when the supply of the raw material gas is stopped when the vaporizer temperature Tv falls below the threshold value Tvref in order to suppress the coking in the reformer 33 and the flooding of the fuel cell stack 36, the combustion section temperature Tc In addition, since the stack temperature Ts is relatively high, the anode of the fuel cell stack 36 is exposed to an oxygen atmosphere at a high temperature, and there is a concern that the oxidative deterioration of the anode is promoted. Based on these, in the present embodiment, when the vaporizer temperature Tv falls below the threshold Tvref when the combustion section temperature Tc is equal to or higher than the threshold Tcref1 or when the stack temperature Ts is equal to or higher than the threshold Tsref1, the source gas supply device 40 The supply of the raw material gas, the supply of the reforming water from the reforming water supply device 55, and the supply of the air from the air supply device 50 are all stopped. By stopping the supply of the reforming water, it is possible to suppress the flooding of the fuel cell stack 36, and by stopping the supply of the raw material gas together with the stopping of the supply of the reforming water, the coking in the reformer 33 is reduced. By stopping the supply of air together with the supply of the raw material gas and the reforming water, the exposure of the anode of the fuel cell stack 36 to an oxygen atmosphere at a high temperature is suppressed, and the oxidative deterioration of the anode is suppressed. Can be suppressed from being promoted. That is, when the system is stopped, coking in the reformer 33, flooding of the fuel cell stack 36, and promotion of oxidative deterioration of the anode can be suppressed.

  In this embodiment, when the abnormal-time stop processing is executed, the user's next instruction to start the system is prohibited (rejected), or the fact that an abnormal time has occurred or the fact that the abnormal-time stop processing has been executed is stored in the EEPROM 84. These are automatically notified to the service center, or displayed on the display panel 90 to notify the user and the service center. By doing so, it is possible to prevent secondary failure, improve safety, and improve the workability of maintenance by the service center operator.

  In the fuel cell system 10 of the present embodiment described above, when the system is stopped, the carburetor temperature Tv falls below the threshold Tvref when the combustion section temperature Tc is equal to or higher than the threshold Tcref1 or when the stack temperature Ts is equal to or higher than the threshold Tsref1. Then, as an abnormal time stop process, the supply of the source gas from the source gas supply device 40, the supply of the reforming water from the reforming water supply device 55, and the supply of the air from the air supply device 50 are all stopped. This can prevent coking in the reformer 33, flooding of the fuel cell stack 36, and promotion of oxidative degradation of the anode when the system is stopped.

  In the above-described embodiment, when the combustion section temperature Tc is lower than the threshold Tcref1 and the stack temperature Ts is lower than the threshold Tsref1 when the vaporizer temperature Tv is equal to or higher than the threshold Tvref, the supply of the source gas from the source gas supply device 40 Although the supply of the reforming water from the reforming water supply device 55 is stopped at the same time, the supply of the raw material gas from the raw material gas supply device 40 is stopped, and then the reforming water from the reforming water supply device 55 is stopped. May be stopped.

  In the above embodiment, the temperature sensor 92 for detecting the combustion section temperature Tc and the temperature sensor 93 for detecting the stack temperature Ts are provided, but one of the temperature sensors 92 and 93 is not provided (omitted). It may be a thing. When the temperature sensor 92 is omitted, the processing of steps S120 and S170 of the stop control routine of FIG. 2 is omitted, and when the temperature sensor 93 is omitted, the processing of steps S130 and S180 of the stop control routine of FIG. 2 is omitted. Good.

  In the above-described embodiment, the temperature sensors 92 and 93 are provided. However, in addition to or instead of at least one of them, the temperature of the reformer 33 (reforming A reformer temperature sensor for detecting the reformer temperature Tr) may be provided.

  For example, when a reformer temperature sensor is provided instead of the temperature sensor 92, a stop control routine of FIG. 4 may be executed instead of the stop control routine of FIG. The stop control routine of FIG. 4 is the same as the stop control routine of FIG. 2 except that the processes of steps S110b, S120b, S160b, and S170b are executed instead of the processes of steps S110, S120, S160, and S170. Therefore, the same processing is denoted by the same step number, and the detailed description is omitted.

  In the stop control routine of FIG. 4, the vaporizer temperature Tv from the temperature sensor 91, the stack temperature Ts from the temperature sensor 93, and the reformer temperature Tr from the reformer temperature sensor are input (step S110b). The temperature Tr is compared with the threshold value Trref1 (step S120b), and the stack temperature Ts is compared with the threshold value Tsref1 (step S130). Here, the threshold value Trref1 is determined in the same manner as the threshold value Tcref1 and the threshold value Tsref1. When the reformer temperature Tr is equal to or higher than the threshold value Trref1 or when the stack temperature Ts is equal to or higher than the threshold value Tsref1, the process proceeds to step S140. On the other hand, when the reformer temperature Tr is less than the threshold value Trref1 and the stack temperature Ts is less than the threshold value Tsref1, the process proceeds to step 150.

  After executing the processing in step S150, the stack temperature Ts from the temperature sensor 93 and the reformer temperature Tr from the reformer temperature sensor are also input (step S160b), and the reformer temperature Tr is compared with the threshold value Trref2. At the same time (step S170b), the stack temperature Ts is compared with a threshold value Tsref2 (step S180). Here, the threshold value Trref2 is determined in the same manner as the threshold value Tcref2 and the threshold value Tsref2. When the reformer temperature Tr is equal to or higher than the threshold value Trref2 or when the stack temperature Ts is equal to or higher than the threshold value Tsref2, the process returns to step S160b. On the other hand, when the reformer temperature Tr is less than the threshold value Trref2 and the stack temperature Ts is less than the threshold value Tsref2, the routine proceeds to step 190.

  Even when the stop control routine of FIG. 4 is executed, the same effect as that when the stop control routine of FIG. 2 is executed can be obtained.

  In the above-described embodiment, the temperature sensor 91 is provided near the inlet of the reformer 33, but may be provided near the outlet of the vaporizer 32.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the section of “Means for Solving the Problems” will be described. In the embodiment, the fuel cell stack 36 corresponds to a “fuel cell”, the vaporizer 32 corresponds to a “vaporizer”, the reformer 33 corresponds to a “reformer”, and the combustion unit 34 corresponds to a “combustion unit”. , The raw material gas supply device 40 corresponds to the “raw material gas supply device”, the reformed water supply device 55 corresponds to the “reformed water supply device”, and the air supply device 50 corresponds to the “oxidizing gas supply device”. , The temperature sensor 91 corresponds to a “vaporizer temperature sensor”, the temperature sensors 92 and 93 correspond to a “temperature detector”, and the control device 80 corresponds to a “control device”. The temperature sensor 93 corresponds to a “battery temperature sensor”, the reformer temperature sensor corresponds to a “reformer temperature sensor”, and the temperature sensor 92 corresponds to a “combustion section temperature sensor”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the section of the means for solving the problem is as follows. This is merely an example for specifically describing a mode for carrying out the invention, and thus does not limit the elements of the invention described in the section of “Means for Solving the Problems”. That is, the interpretation of the invention described in the section of the means for solving the problem should be interpreted based on the description of the section, and the embodiment is an embodiment of the invention described in the section of the means for solving the problem. This is only a specific example.

  As described above, the embodiments for carrying out the present invention have been described. However, the present invention is not limited to these embodiments at all, and can be carried out in various forms without departing from the gist of the present invention. Of course.

  INDUSTRIAL APPLICABILITY The present invention is applicable to a fuel cell system manufacturing industry and the like.

  Reference Signs List 1 gas supply source, 2 commercial power system, 3 power line, 4 load, 10 fuel cell system, 20 power generation unit, 22 housing, 22a intake port, 22b exhaust port, 24 ventilation fan, 30 fuel cell module, 31 module case , 32 vaporizer, 33 reformer, 34 combustion section, 35 ignition heater, 36 fuel cell stack, 37 combustion catalyst, 40 source gas supply device, 41 source gas supply pipe, 42, 43 source gas supply valve, 44 orifice, 45 raw material gas pump, 46 desulfurizer, 47 pressure sensor, 48 flow sensor, 50 air supply device, 51 air supply tube, 52 filter, 53 air blower, 54 flow sensor, 55 reformed water supply device, 56 reformed water supply tube, 57 reformed water tank, 58 reformed water pump, 60 exhaust heat recovery device, 61 circulation pipe, 6 Heat exchanger, 63 circulation pump, 66 condensed water supply pipe, 67 exhaust gas discharge pipe, 70 power conditioner, 78 power supply board, 80 control device, 81 CPU, 82 ROM, 83 RAM, 84 timer, 90 display panel, 91 ~ 93 Temperature sensor, 100 hot water supply unit, 101 hot water storage tank.

Claims (5)

A fuel cell that generates power based on the fuel gas supplied to the anode and the oxidant gas supplied to the cathode,
A vaporizer for evaporating the reformed water to produce steam,
A reformer that reforms the mixed gas of the steam and the raw material gas into the fuel gas and supplies the fuel gas to the anode;
A combustion unit that heats the vaporizer and the reformer by burning off-gas that has passed through the fuel cell,
A source gas supply device for supplying the source gas to the reformer,
A reforming water supply device for supplying the reforming water to the vaporizer,
An oxidizing gas supply device that supplies the oxidizing gas to the cathode,
A vaporizer temperature sensor that is provided in a fuel cell module having the fuel cell, the vaporizer, the reformer, and the combustion unit, and detects a temperature of the vaporizer;
A temperature detector provided at a position different from the vaporizer temperature sensor in the fuel cell module;
When the system is stopped, when the temperature detected by the temperature detector falls below a first threshold, the source gas supply device is controlled such that the supply of the source gas from the source gas supply device is stopped. Together with or after controlling the reforming water supply device so that the supply of the reforming water from the reforming water supply device is stopped, and thereafter, the oxidizing gas from the oxidizing gas supply device is controlled. A control device that executes a normal stop process for controlling the oxidizing gas supply device so that the supply of the gas is stopped,
A fuel cell stem comprising:
The control device is configured such that, when the system is stopped, the temperature of the vaporizer detected by the vaporizer temperature sensor when the temperature detected by the temperature detector is equal to or higher than the first threshold is lower than a second threshold. At this time, the supply of the source gas from the source gas supply device, the supply of the reforming water from the reforming water supply device, and the supply of the oxidizing gas from the oxidizing gas supply device all stop. Executing an abnormal time stop process for controlling the raw material gas supply device, the reformed water supply device, and the oxidizing gas supply device so that
Fuel cell system. The fuel cell system according to claim 1, wherein
The control device, when the system is stopped by the abnormal time stop processing, prohibits the user from instructing the next system start, storage processing of the system abnormality, notification of the system abnormality, and notification to the service center. Do at least one,
Fuel cell system. The fuel cell system according to claim 1 or 2,
The temperature detector is at least one of a battery temperature sensor that detects the temperature of the fuel cell, a reformer temperature sensor that detects the temperature of the reformer, and a combustion part temperature sensor that detects the temperature of the combustion part. Having one,
Fuel cell system. The fuel cell system according to claim 3, wherein
The controller detects the temperature of the fuel cell when the temperature of the fuel cell detected by the battery temperature sensor and the temperature of the reformer detected by the reformer temperature sensor are lower than respective thresholds. It is determined that the temperature detected by has reached less than the first threshold,
Fuel cell system. The fuel cell system according to claim 3, wherein
The controller detects the temperature of the fuel cell detected by the battery temperature sensor and the temperature of the combustion unit detected by the combustion unit temperature sensor below the respective thresholds, and detects the temperature by the temperature detector. Determining that the temperature to be performed has reached less than the first threshold value;
Fuel cell system.

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