JP2019149346A - Fuel cell system and operation method therefor - Google Patents

Abstract

To provide a fuel cell system and operation method therefor, capable of performing self start-up without performing power supply to a system.SOLUTION: A fuel cell device (2) comprises: a SOFC (10) for generating power using electrochemical reaction between fuel gas and oxidant gas; an inverter (20) connected to a system power supply (3) to convert DC current generated by the SOFC to AC current; auxiliaries (30) actuated by predetermined power supply; and a first switching unit (40) capable of performing switching between a connection state and non-connection state of the auxiliaries to the inverter. A fuel cell system (1) comprises: the fuel cell device; a second switching unit (4) capable of performing switching between an interconnection state and parallel-off state of the fuel cell device with the system power supply; and a control unit (70) for controlling actuation of the first switching unit, the second switching unit, and the auxiliaries.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system and an operation method thereof.

  In recent years, development of a solid oxide fuel cell (SOFC) has been promoted. SOFC is a power generation mechanism in which oxide ions generated at the air electrode permeate the electrolyte and move to the fuel electrode, where the oxide ions react with hydrogen or carbon monoxide to generate electrical energy. . The SOFC has the characteristics that the power generation operating temperature is the highest (for example, 600 ° C. to 1000 ° C.) and the power generation efficiency is the highest among the currently known fuel cell configurations.

  Patent Document 1 discloses a fuel cell system in which a solid oxide fuel cell is connected to an external load such as a motor. In such a fuel cell system, at the time of start-up, before the power generated by the fuel cell is supplied to an external load, power is supplied to the reformer and the blower to use the energy.

JP 2010-282831 A

  However, the fuel cell system of Patent Document 1 is not connected to the system power, and thus there is no disclosure regarding a technique for starting without supplying power to the system power. In a fuel cell system, it has been desired to be able to start up independently without supplying power to the system at the preparation stage after installation or during maintenance.

  This invention is made | formed in view of this point, and it is set as one of the objectives to provide the fuel cell system which can be started independently, without supplying electric power to a system | strain, and its operating method.

  In one aspect, the fuel cell system of the present embodiment includes a solid oxide fuel cell that generates electric power by an electrochemical reaction between a fuel gas and an oxidant gas, and an anode that supplies the fuel gas to the solid oxide fuel cell. A gas supply path, an inverter connected to a system power supply and converting a direct current generated by the solid oxide fuel cell into an alternating current; a load in a power generation device that operates by a predetermined power supply; and the power generation for the inverter A fuel cell device including a first switching unit capable of switching between a connected state and a non-connected state of the in-device load, and a connection state and a disconnection state between the fuel cell device and the system power source can be switched. A second switching unit, the first switching unit, the second switching unit, and a control unit that controls the operation of the load in the power generation device are provided.

  In one aspect of the method for operating the fuel cell system of the present embodiment, a solid oxide fuel cell that generates electric power by an electrochemical reaction between a fuel gas and an oxidant gas, and the fuel gas into the solid oxide fuel cell. An anode gas supply path for supplying, a recirculation path for recirculating exhaust gas discharged from the solid oxide fuel cell to the anode gas supply path, and a system power supply; An inverter that converts generated DC current into AC current, a load in the power generator that operates by supplying a predetermined power, and a first switching unit that can switch between a connected state and a disconnected state of the load in the power generator relative to the inverter. And a second switching unit capable of switching between a connected state and a disconnected state of the fuel cell device and the system power supply. The solid oxide fuel cell, wherein the power supply is supplied from the system power supply to the load in the power generation device as the interconnected state in the second switching unit while the non-connected state in the first switching unit. And after the solid oxide fuel cell has been heated to a predetermined temperature, the disconnected state is established in the second switching portion and the connected state is established in the first switching portion. And a step of consuming electric power generated in the battery by the load in the power generation device via the inverter.

  According to the present invention, at the time of start-up, until the solid oxide fuel cell is heated to a predetermined temperature, the second switching unit feeds power from the system power source to the load in the power generation apparatus as a connected state, and the power of the system power source Thus, the solid oxide fuel cell can be heated. At this time, the inverter and the load in the power generator can be disconnected from each other by the first switching unit. On the other hand, after the temperature of the solid oxide fuel cell rises to a predetermined temperature, the second switching unit disconnects the power supply from the system power supply and stops the power supply from the system power source. Can be connected. At this time, the electric power generated in the solid oxide fuel cell can be consumed by the load in the power generation apparatus via the inverter, and can be brought into a self-starting state without supplying power to the system. Thereby, it is possible to maintain the disconnected state while generating power with the solid oxide fuel cell, and it is possible to perform various operations on the condition.

It is a block diagram which shows the fuel cell system of 1st Embodiment. It is a block diagram which shows the fuel cell apparatus of 1st Embodiment. It is a functional block diagram which shows the control system of the fuel cell system by 1st Embodiment. It is a flowchart which shows the operation | movement at the time of starting of the fuel cell system by 1st Embodiment. It is a flowchart which shows the operation | movement at the time of starting of the fuel cell system by 1st Embodiment. It is a time chart for demonstrating the operation | movement at the time of starting of the fuel cell system by 1st Embodiment. It is a block diagram which shows the fuel cell apparatus of 2nd Embodiment.

[First Embodiment]
The fuel cell system according to the first embodiment will be described in detail with reference to FIG. FIG. 1 is a block diagram showing the fuel cell system of the first embodiment.

  As shown in FIG. 1, the fuel cell system 1 includes a fuel cell device 2 and a system power supply 3. The system power source 3 may be a commercial power source or a backup power source including a simple power generator having a secondary battery, an engine, and the like. The fuel cell device 2 includes a solid oxide fuel cell (SOFC) 10, an inverter 20, an auxiliary device 30, a first switching unit 40, and a second switching unit 4. .

  The SOFC 10 has a cell stack in which a plurality of cells are stacked or assembled. Each cell has a basic configuration in which an electrolyte is sandwiched between an air electrode and a fuel electrode, and a separator is interposed between the cells. Each cell of the cell stack is electrically connected in series. The SOFC 10 is a power generation mechanism that generates electric energy when oxide ions generated at the air electrode permeate the electrolyte and move to the fuel electrode, and the oxide ions react with hydrogen or carbon monoxide at the fuel electrode. .

  The inverter 20 converts a direct current generated (generated) by the SOFC 10 into an alternating current. The inverter 20 has means for switching between current control or power control and voltage control. These controls will be described later.

  The auxiliary machinery 30 includes a first heater (heating means) 31 that heats reformed water, which will be described later, a second heater (heating means) 32 that heats air (oxidant gas) supplied to the SOFC 10, and a third heater ( Heating means) 33. Further, the auxiliary machinery 30 includes a reaction air blower (sending means) 34 for supplying air to the SOFC 10 and a recirculation blower (sending means) 35 for sending exhaust gas discharged through the fuel electrode of the SOFC 10. . The devices 31 to 35 constituting the auxiliary machinery 30 are operated by power supply from the SOFC 10 or the system power supply 3, and each is used as a load in the power generator.

  The inverter 20 of the fuel cell device 2 is connected to the system power supply 3 via the power transmission path M1. In the power transmission path M1, a first switching unit 40 is provided on the inverter 20 side, and a second switching unit 4 is provided on the system power source 3 side from the first switching unit 40. An electromagnetic switch or the like is used for the first switching unit 40 and the second switching unit 4. In the power transmission path M <b> 1, the auxiliary power transmission path M <b> 2 branches from between the first switching unit 40 and the second switching unit 4.

  The generated power of the SOFC 10 passes through the inverter 20 and is connected to the auxiliary machinery 30 via the first switching unit 40. The first switching unit 40 is provided to be able to switch between a connected state and a disconnected state of the auxiliary machinery 30 with respect to the inverter 20. The output power from the inverter 20 (generated power of the SOFC 10) is connected to the auxiliary machinery 30 when the first switching unit 40 is on, and the auxiliary power 30 when the first switching unit 40 is off. Disconnected state.

  The AC power of the system power supply 3 is connected to the fuel cell device 2 via the second switching unit 4. The second switching unit 4 is provided so as to be able to switch between a connected state and a disconnected state between the fuel cell device 2 and the system power supply 3. The system power supply 3 is connected to the fuel cell device 2 when the second switching unit 4 is on, and is disconnected from the fuel cell device 2 when the second switching unit 4 is off. The device 2 performs a self-sustained operation. When the second switching unit 4 is in the on state (interconnection state) and the first switching unit 40 is in the off state, the AC power of the system power supply 3 is supplied to the accessories 30.

  During the interconnected operation in which both the first switching unit 40 and the second switching unit 4 are in the on state, the generated power of the SOFC 10 is supplied to the system, while during the independent operation, the generated power is supplemented with a load smaller than the rated maximum power. It is consumed in the apparatus by the machinery 30 or the like.

  Next, the configuration of the fuel cell device 2 will be described. FIG. 2 is a block diagram showing the fuel cell device according to the first embodiment. As shown in FIG. 2, the SOFC 10 of the fuel cell device 2 includes an anode gas channel (fuel gas channel, reducing gas channel) 11 and a cathode gas channel (oxidant gas channel) 12. Yes.

  The fuel cell device 2 includes an anode gas supply path 51 connected to the inlet of the anode gas flow path 11 and a cathode gas supply path 52 connected to the inlet of the cathode gas flow path 12. During power generation of the SOFC 10, fuel gas is supplied to the anode gas passage 11 via the anode gas supply passage 51, and the fuel gas flows through the anode gas passage 11. Further, the oxidant gas is supplied to the cathode gas channel 12 via the cathode gas supply channel 52, and the oxidant gas flows through the cathode gas channel 12. A direct current is generated when the fuel gas (reducing gas) supplied to the anode gas passage 11 and the oxidant gas supplied to the cathode gas passage 12 cause an electrochemical reaction (the SOFC 10 generates electricity). . The direct current generated by the SOFC 10 is converted into alternating current (DC / AC conversion) by the inverter 20.

  The fuel cell device 2 includes a reforming steam supply path 53 connected to the anode gas supply path 51. The reforming steam supply path 53 is provided with a first heater 31 constituting auxiliary equipment. In the reforming steam supply path 53, the supplied reforming water is heated by the first heater 31 to generate reforming steam. Then, the generated reforming steam is supplied to the anode gas supply path 51, and the fuel gas is steam reformed into a reducing gas. As the fuel gas, a gas composed of a hydrocarbon-based fuel such as city gas (methane gas) natural gas or biogas such as digestion gas is used.

  The fuel cell device 2 includes a second heater 32, a third heater 33, and a reaction air blower 34 that are provided in the cathode gas supply path 52 and respectively constitute auxiliary machinery. Air in the atmosphere is taken into the cathode gas supply path 52 as an oxidant gas by the reaction air blower 34. In the cathode gas supply path 52, the taken oxidant gas (air) is heated by the second heater 32 and the third heater 33 and supplied to the cathode gas flow path 12.

  The cathode gas supply path 52 is provided with the second heater 32 and the third heater 33 as two heaters. However, either one of them may be omitted and a single heater may be provided. A heater may be provided. By using two or more heaters, it is possible to adjust the amount of heat and power consumption by changing the number of heaters and the number of heaters that are operated by switching on / off control of each heater. You can plan.

  The fuel cell device 2 includes an anode gas discharge path 55 connected to the outlet portion of the anode gas flow path 11 and a cathode gas discharge path 56 connected to the outlet portion of the cathode gas flow path 12. The fuel cell device 2 also includes a combustor 57 connected to the anode gas discharge path 55 and the cathode gas discharge path 56. The anode gas discharge path 55 discharges exhaust gas from the outlet of the anode gas flow path 11 to the combustor 57, and the cathode gas discharge path 56 discharges exhaust gas from the outlet of the cathode gas flow path 12 to the combustor 57. To discharge.

  The combustor 57 removes impurities in the exhaust gas by burning the exhaust gas discharged from the SOFC 10, and then exhausts the exhaust gas. The heat generated when the combustor 57 burns the exhaust gas is used by the hot water heat exchanger 58 to heat the low temperature water circulating from an external tank (not shown) or the like to the high temperature water.

  The fuel cell device 2 includes a recirculation path 60 that branches from the anode gas discharge path 55. The recirculation path 60 recirculates the exhaust gas from the outlet of the anode gas flow path 11 from the anode gas discharge path 55 to the anode gas supply path 51. The recirculation path 60 is provided with a recirculation blower 35 constituting auxiliary equipment for sending exhaust gas into the recirculation path 60.

  A control valve 61 is provided on the downstream side of the branch point of the recirculation path 60 in the anode gas discharge path 55. The control valve 61 adjusts the pressure of the anode gas discharge path 55 by switching its open / closed state. Further, the control valve 61 adjusts the flow rate of the exhaust gas flowing from the anode gas discharge path 55 to the combustor 57 and the flow rate of the exhaust gas flowing to the recirculation path 60 according to the degree of opening and closing thereof.

  FIG. 3 is a functional block diagram showing a control system of the fuel cell system according to the first embodiment. As shown in FIG. 3, the fuel cell system 1 includes a control unit 70 that comprehensively drives and controls each component of the fuel cell system 1. More specifically, the control unit 70 includes the first switching unit 40, the second switching unit 4, the first heater 31, the second heater 32, the third heater 33, the reaction air blower 34, the recirculation blower 35, and the regulating valve 61. The drive control, on / off control or open / close control of each of these components is executed when the SOFC 10 is activated.

  Further, the control unit 70 executes control for switching the control method (current control, power control, voltage control) of the inverter 20. In the inverter 20, in voltage control (voltage constant control: AVR operation), when power is supplied to the auxiliary machinery 30, the current flowing through the auxiliary machinery 30 is made constant when the load on the auxiliary machinery 30 changes and the voltage is constant. Change. In the power control, when power is supplied to the system power supply 3, the active power to be output and the reactive power control are controlled as necessary.

  4 and 5 are flowcharts showing the operation at the time of starting the fuel cell system according to the first embodiment, and FIG. 6 explains the operation at the time of starting the fuel cell system according to the first embodiment. It is a time chart for. Hereinafter, with reference to FIGS. 4 to 6, the operation at the time of startup of the fuel cell system 1 (contents of control by the control unit 70) will be described in detail.

  In the flowchart of FIG. 4, in step ST <b> 1, the control unit 70 turns off the first switching unit 40. In step ST2, the control unit 70 turns on the second switching unit 4. By executing the processing of step ST1 and step ST2, the system power supply 3 and the fuel cell device 2 are connected to each other, and the AC power from the system power supply 3 can be supplied to the auxiliary devices 30.

  In step ST3, the control unit 70 turns on the reaction air blower 34. In step ST4, the control unit 70 turns on one of the second heater 32 and the third heater 33. In step ST5, the control unit 70 turns on the recirculation blower 35. By executing the processing of step ST3, step ST4, and step ST5, the oxidant gas (air) taken from the reaction air blower 34 is heated by the second heater 32 or the third heater 33 to the cathode gas supply path 52. Supplied. Then, the heated oxidant gas flows through the cathode gas flow path 12, so that the temperature of the SOFC 10 increases (see FIG. 6).

  In step ST6, the control unit 70 determines whether or not the SOFC 10 has reached a predetermined first temperature threshold T1 (predetermined temperature, see FIG. 6). When the SOFC 10 has reached the first temperature threshold value T1 (step ST6: Yes), the process proceeds to step ST7. When the SOFC 10 has not reached the first temperature threshold value T1 (step ST6: No), it waits for the SOFC 10 to reach the first temperature threshold value T1. The first temperature threshold T1 can be set, for example, within a range of 300 ° C to 600 ° C.

  In step ST7, the SOFC 10 has reached the first temperature threshold T1, and the control unit 70 turns on the first heater 31. In step ST8, supply of reforming water is started from a reforming water supply device (not shown) (see FIG. 6), and in step ST9, fuel gas is supplied from the fuel gas supply device (not shown) to the anode gas supply path 51. Start supplying. By performing the processing from step ST6 to step ST8, the reforming water is generated by heating the reforming water by the first heater 31. The fuel gas steam-reformed with the reforming steam is supplied to the SOFC 10 through the anode gas supply path 51. As a result, an oxidant gas supplied to the cathode gas passage 12 and a fuel gas supplied to the anode gas passage 11 cause an electrochemical reaction inside the SOFC 10 to generate a direct current (generate power). .

  As shown in FIG. 5, in step ST <b> 10, the control unit 70 performs back pressure adjustment on the SOFC 10 side of the anode gas discharge path 55 via the adjustment valve 61. By performing the process of step ST10, the exhaust gas discharged from the anode gas discharge path 55 via the anode gas flow path 11 of the SOFC 10 flows into the recirculation path 60. Then, exhaust gas flows from the recirculation path 60 to the anode gas supply path 51 and is recirculated as fuel gas. Since the recirculated exhaust gas is heated by passing through the SOFC 10, when it flows into the anode gas supply path 51, it contributes to reforming of the fuel gas supplied from the fuel gas supply device (not shown). It will be. You may perform the process of step ST6-step ST10 substantially simultaneously.

  In step ST11, the control unit 70 determines whether or not the SOFC 10 has reached a predetermined second temperature threshold T2 (predetermined temperature, see FIG. 6). When the SOFC 10 has reached the second temperature threshold T2 (step ST11: Yes), the process proceeds to step ST12. When the SOFC 10 has not reached the second temperature threshold value T2 (step ST11: No), it waits for the SOFC 10 to reach the second temperature threshold value T2. The second temperature threshold T2 can be set, for example, within a range of 600 ° C to 900 ° C.

  In step ST12, the control unit 70 activates the inverter 20, and converts the direct current generated in the SOFC 10 into an alternating current. In step ST13, the control unit 70 turns the second switching unit 4 off. In step ST14, the control unit 70 turns on the first switching unit 40. By performing the processing of step ST12 to step ST14, the system power supply 3 and the fuel cell device 2 are disconnected from each other, and the AC power of the inverter 20 can be supplied to the auxiliary machinery 30. In other words, the fuel cell device 2 is in a state of being operated independently by the power generation of the SOFC 10 without receiving external power supply.

  In step ST15, the control unit 70 turns on the other one of the second heater 32 and the third heater 33 that has not been turned on in step ST4, that is, turns both the second heater 32 and the third heater 33 on. To do. As a result, the SOFC 10 further rises in temperature from the second temperature threshold T2 via the cathode gas flow path 12.

  After executing the process of step ST4, the second heater 32 and the third heater 33 can be sequentially operated with a predetermined time lag when executing the process of step ST15. Thereby, the control unit 70 can control to gradually increase the output power of the SOFC 10 (see FIG. 6) and gradually increase the power consumed as the auxiliary machinery 30. Therefore, a rapid temperature rise from a low temperature state can be suppressed, and the cell stack of the SOFC 10 and thus the auxiliary machinery 30 can be prevented from being deteriorated and damaged, and a stable operation of the system can be realized.

  In step ST16, the control unit 70 stops the supply of the reforming water from the reforming water supplier (not shown) (see FIG. 6). In step ST17, the control unit 70 turns off the first heater 31. By performing the processing of step ST16 and step ST17, the reforming by the reforming steam is stopped, and the fuel gas is reformed by the exhaust gas recirculated from the recirculation path 60. In other words, only the water vapor contained in the anode gas channel 11 is the total amount of water vapor necessary for the fuel cell device 2 to reform and produce the fuel gas into the reducing gas without receiving the reformed water supply from the outside. The water self-sustained state secured in step 1 is established, and the start-up of the self-sustaining operation is completed. Such a water self-supporting state can be said to be a technique unique to SOFC 10 in which water (water vapor) is generated at the anode by the electrochemical reaction of SOFC 10.

  Note that the timing of executing the processes of step ST16 and step ST17 is such that the temperature of the SOFC 10 reaches a predetermined threshold, or the output power from the inverter 20 becomes a predetermined ratio (for example, 20 to 50%) with respect to the rated power. Can be illustrated.

  As described above, in the fuel cell system 1, when the SOFC 10 is activated, until the SOFC 10 is heated to the first temperature threshold value T <b> 1, the second switching unit 4 switches the system power supply 3 to the accessories 30 until the SOFC 10 is connected. The SOFC 10 can be heated by the power supplied from the system power supply 3. At this time, the inverter 20 and the auxiliary machinery 30 can be disconnected from each other by the first switching unit 40. On the other hand, after the SOFC 10 has risen to the second temperature threshold value T2, the second switching unit 4 disconnects the power supply from the system power source 3 and stops the power supply from the system power source 3, and the first switching unit 40 causes the inverter 20 and the auxiliary machinery 30 to be disconnected. Can be connected. At this time, the electric power generated by the SOFC 10 can be consumed by the auxiliary devices 30 via the inverter 20, and can be brought into a self-starting state without supplying power to the system power supply 3. As a result, the disconnected state can be easily maintained while generating power with the SOFC 10, and various operations (inverter operation check, maintenance operation, etc.) on the condition can be performed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the following description, the same reference numerals are used for the same or equivalent components as those in the first embodiment, and the description may be omitted or simplified.

  FIG. 7 is a block diagram showing a fuel cell system according to the second embodiment. The fuel cell device 2 according to the second embodiment has a configuration in which fourth to eighth heaters (heating means) 74 to 78 are added to the first embodiment. The fourth heater 74 heats the fuel gas supplied from the fuel gas supply device (not shown) to the anode gas supply path 51. The fifth heater 75 heats the reducing gas flowing downstream from the junction of the reforming steam supply path 53 and the recirculation path 60 in the anode gas supply path 51. The sixth heater 76 heats the cell stack of the SOFC 10. The seventh heater 77 heats the hot water circulating in the hot water heat exchanger 58 as the hot water for exhaust heat recovery of the SOFC 10. The eighth heater 78 heats the atmosphere.

  Each of the fourth to eighth heaters 74 to 78 is also connected to the control unit 70 (see FIG. 3), and the control unit 70 performs operation control and on / off control. Although the case where each of the fourth to eighth heaters 74 to 78 is single for each of the above-described heating targets is illustrated, a configuration may be adopted in which a plurality of heaters are installed and heated in stages. Although not shown in FIG. 7, for example, a heater may be installed in the cathode gas discharge path 56 or the recirculation path 60.

  In the fuel cell device 2, the first to eighth heaters 31 to 33 and 74 to 78 may be appropriately omitted, and at least one of the heaters 31 to 33 and 74 to 78 may be used. It can be set as the structure which selected and installed. For example, when the first heater 31 and the eighth heater 78 are installed and the second to seventh heaters 31, 32, 74 to 77 are omitted, the target to be heated at the time of self-sustained activation of the fuel cell device 2 is not limited to reforming water. Becomes the atmosphere. That is, it is possible to consume the electric power generated in the SOFC 10 while suppressing the temperature increase rate of the fuel cell device 2 itself. As described above, in order to realize various functions and functions, any one of the first to eighth heaters 31 to 33 and 74 to 78 constituting the auxiliary machinery 30 to be installed or controlled for operation is selected in any combination. It becomes possible to drive.

  Here, the function when the first to eighth heaters 31 to 33, 74 to 78, etc. are operated will be exemplified below. In the SOFC 10, if the power generation load is low and the amount of water generated by power generation is small, the entire hydrocarbon fuel to be introduced cannot be steam reformed even if the exhaust gas discharged from the anode gas passage 11 is recirculated. Some of the catalyst used will coke. Thus, for example, coking can be prevented by consuming electric power by the first heater 31 and generating reformed steam. Further, the SOFC 10 can be maintained at a high temperature or a high temperature by consuming electric power by the second heater 32 and the third heater 33 and heating the oxidant gas (air). Further, the SOFC 10 can be maintained at a high temperature by heating the fuel gas by consuming electric power with the fourth heater 74. Further, water is consumed in the fifth heater 75 or a heater (not shown) installed in the recirculation path 60 or the piping at the outlet of the recirculation blower 35 to heat the recirculation gas, whereby water vapor in the recirculation path 60 is obtained. And the SOFC 10 can be maintained at a high temperature. Further, the sixth heater 76 can consume electric power to heat the SOFC 10 and maintain the SOFC 10 at a high temperature. By maintaining the SOFC 10 at a high temperature, high power generation efficiency can be maintained. Further, when the SOFC 10 has a high output or the outside air temperature is high, there is a possibility that the control target temperature may be exceeded, so that power is consumed by the heaters 77 and 78 to heat the hot water or the atmosphere. Prevent overheating of the battery. When heating the atmosphere, it can be used as a heat source for heating and drying processes. When warm water is heated, it can be used as a heat source such as hot water supply, heating, and steam generation. By consuming electric power with a heater for heating the exhaust, it is possible to prevent the exhaust from becoming white smoke when the outside air temperature is low.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, function, and the like of the components illustrated in the accompanying drawings are not limited thereto, and can be appropriately changed within a range in which the effects of the present invention are exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  In each of the above embodiments, the fuel gas supplied to the anode gas supply path 51 is steam reformed to generate the fuel gas. Instead, hydrogen gas is supplied from the cylinder or the like as the fuel gas to the anode gas supply path 51. May be. In this case, the supply of the reforming water, the first heater 31 and the heating thereof can be omitted, and the power consumption at the time of activation can be reduced and the configuration can be simplified.

  In each of the above embodiments, the power supply to the reaction air blower 34 and the recirculation blower 35 is switched between the SOFC 10 and the system power supply 3 as described above, but the power supply to at least one of them is not switched, You may make it perform electric power supply from the power supply 3 always. Further, in each of the heaters 31 to 33 and 74 to 78, power supply may be always performed from the system power supply 3 without switching power supply to at least one of them.

  In each of the above embodiments, the reforming by the reforming steam is started as a self-supporting state of water, but the supply amount of the reforming steam is reduced, and the reforming steam and the exhaust gas from the recirculation path 60 are reduced. The fuel gas may be reformed with both the water vapor contained in the fuel gas.

  In each of the above embodiments, the recirculation path 60 is provided. However, the recirculation path 60 may be omitted and the exhaust gas from the anode gas discharge path 55 may be discharged to the combustor 57.

  The fuel cell system and the operation method thereof according to the present invention are suitable for application to fuel cell systems for household use, business use, and other industrial fields.

DESCRIPTION OF SYMBOLS 1 Fuel cell system 2 Fuel cell apparatus 3 System power supply 4 2nd switching part 10 Solid oxide fuel cell (SOFC: Solid Oxide Fuel Cell)
20 Inverter 30 Auxiliary equipment (load in generator)
31 1st heater (electric generator internal load, heating means)
32 Second heater (load in generator, heating means)
33 3rd heater (load in generator, heating means)
34 Reaction air blower (load in power generator, delivery means)
35 Recirculation blower (load in generator, delivery means)
40 1st switching part 51 Anode gas supply path 60 Recirculation path 70 Control part 74 4th heater (electric generator internal load, heating means)
75 5th heater (load in generator, heating means)
76 6th heater (load in generator, heating means)
77 7th heater (load in generator, heating means)
78 8th heater (load in generator, heating means)

Claims (7)

A solid oxide fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidant gas;
An anode gas supply path for supplying the fuel gas to the solid oxide fuel cell;
An inverter connected to a system power source and converting a direct current generated by the solid oxide fuel cell into an alternating current;
A load in the power generator that operates by a predetermined power supply; and
A first switching unit capable of switching between a connected state and a disconnected state of the load in the power generator with respect to the inverter;
A second switching unit capable of switching between a connected state and a disconnected state between the fuel cell device and the system power supply;
A fuel cell system comprising: the first switching unit, the second switching unit, and a control unit that controls the operation of the load in the power generator. The solid oxide fuel cell;
The anode gas supply path;
The fuel cell system according to claim 1, further comprising a recirculation path for recirculating the exhaust gas discharged from the solid oxide fuel cell to the anode gas supply path. The load in the power generation device includes at least one of sending means and heating means,
The control unit controls each component of the fuel cell system,
The delivery means delivers at least one of the oxidant gas and the exhaust gas;
The heating means includes the oxidant gas, the fuel gas, reformed water for generating the fuel gas, hot water for recovering exhaust heat of the solid oxide fuel cell, the solid oxide fuel cell, and the atmosphere. The fuel cell system according to claim 1 or 2, wherein at least one of them is heated.   4. The fuel cell system according to claim 3, wherein the control unit performs control to gradually increase the power consumed by the load in the power generation device. 5.   The control unit heats the solid oxide fuel cell by controlling the operation of the load in the power generator, and generates water vapor necessary for generating the fuel gas with water vapor in the exhaust gas flowing through the recirculation path. The fuel cell system according to any one of claims 1 to 4, wherein the entire amount is secured.   6. The fuel cell system according to claim 1, wherein the inverter includes means for switching between current control or power control and voltage control. A solid oxide fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidant gas;
An anode gas supply path for supplying the fuel gas to the solid oxide fuel cell;
A recirculation path for recirculating exhaust gas discharged from the solid oxide fuel cell to the anode gas supply path;
An inverter connected to a system power source and converting a direct current generated by the solid oxide fuel cell into an alternating current;
A load in the power generator that operates by a predetermined power supply; and
A first switching unit capable of switching between a connected state and a disconnected state of the load in the power generator with respect to the inverter;
A second switching unit capable of switching between a connected state and a disconnected state between the fuel cell device and the system power supply, and a method of operating a fuel cell system,
Supplying the power from the system power supply to the load in the power generator as the interconnected state in the second switching unit while heating the solid oxide fuel cell in the disconnected state at the first switching unit;
After the temperature of the solid oxide fuel cell is raised to a predetermined temperature, the connection state is established in the first switching portion while the disconnection state is established in the second switching portion, and the electric power generated in the solid oxide fuel cell is Consuming the load in the power generator via the inverter;
A method for operating a fuel cell system, comprising:

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