JP6817729B2 - Fuel cell control device and control method and power generation system - Google Patents

Description

The present invention relates to a fuel cell control device, a control method, and a power generation system.

A fuel cell is a power generation device that uses a power generation method based on an electrochemical reaction. It has a fuel electrode, which is an electrode on the fuel side, an air electrode, which is an electrode on the air (oxidant gas) side, and only ions between them. It is composed of an electrolyte through which it passes, and various types have been developed depending on the type of electrolyte.

Of these, for example, solid oxide fuel cells (Solid Oxide Fuel Cell: hereinafter referred to as "SOFC") use ceramics such as zirconia ceramics as an electrolyte, and hydrogen, city gas, natural gas, oil, methanol, and coal. It is a fuel cell that is operated by using gas produced from a carbonaceous raw material such as gasified gas by a gasification facility. This SOFC has a high operating temperature of about 700 to 1000 ° C. in order to increase ionic conductivity, and is known as a highly efficient high-temperature fuel cell.

A combined cycle system has been developed in which such an SOFC is combined with an internal combustion engine such as a micro gas turbine (hereinafter referred to as "MGT"). In this MGT, the compressed air discharged from the compressor is supplied to the air electrode of the SOFC, and the high-temperature exhaust fuel gas discharged from the SOFC is supplied to the combustor of the MGT for combustion, and the combustion generated in the combustor is performed. By adiabatic expansion of the gas, the turbine of the MGT is rotationally driven and the generator is rotationally driven, so that power generation with high power generation efficiency is possible.

In such SOFC control, feedback control and feedforward control are used (see, for example, Patent Document 1).
Further, Patent Document 2 includes an exhaust fuel gas supply line for supplying exhaust fuel gas from the SOFC to the combustor of the MGT, a recirculation line for branching from the exhaust fuel gas supply line and circulating the exhaust fuel gas to the SOFC. It is disclosed that a flow rate adjusting valve provided on the path of the exhaust fuel gas supply line is provided, and the gain with respect to the opening degree of the flow rate adjusting valve is adjusted according to the cooperative operation state of the SOFC and the MGT.
Further, in Patent Document 3, when SOFC is started, an oxidant to which a flammable fuel gas is added is supplied to the air electrode of the power generation chamber, and heat generated by catalytic combustion by the added combustible fuel gas is used to generate power. It is disclosed that the temperature of the room is raised.
Further, in Patent Document 4, when the load of SOFC rises, the threshold values of the fuel utilization rate and the minimum temperature of the power generation cell are set for each current value when the load rises until the rated current value is reached, and the respective current values are set. When it reaches, it is determined whether or not the temperature of the power generation cell has reached the threshold value corresponding to each current value, and if there is a power generation cell whose temperature has not reached the threshold value, the load increase is stopped. A method of operating a fuel cell that holds for a certain period of time and thereby restarts the load increase when all the temperatures of the power generation cells reach the threshold value is disclosed.

Japanese Unexamined Patent Publication No. 2003-223912 JP 2015-50106 Japanese Patent No. 5601945 Japanese Unexamined Patent Publication No. 2012-216369

By the way, the power generation chamber of the SOFC has a large heat capacity, and a response delay occurs when controlling the operation amount (for example, air or fuel gas supplied to the SOFC) related to the temperature control of the power generation chamber. Therefore, for example, when the load rises, overshoot may occur in which each control amount (for example, the temperature of the power generation chamber) exceeds a specified value, and if the temperature of a part of the SOFC rises too much, the SOFC There was a risk of damaging.
In addition, in order to suppress overshoot when the load increases, if each operation amount is gradually changed, or if each operation is sequentially operated and each control amount is stabilized, then the next operation is performed. It takes a considerable amount of time for the controlled variable to reach the target value.

The present invention has been made in view of such circumstances, and is a fuel cell control device and control capable of shortening the time to reach a target while suppressing overshoot of a controlled amount when a load is increased. The purpose is to provide a method as well as a power generation system.

The present invention is a fuel cell control device including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged, and a target load setting unit for setting a target load and a target load setting unit. An output current command setting unit that sets an output current command of the fuel cell from the target load using a predetermined current change rate, and a plurality of output current command setting units for changing the load of the fuel cell using the output current command. A control command setting unit that sets a control command to the control system, and when the temperature of the power generation chamber reaches a preset first temperature threshold, the supply of flammable gas to the air electrode is started, and the power generation chamber is started. It is provided with a flammable gas flow rate control unit that stops the supply of the flammable gas to the air electrode when the temperature reaches the supply stop temperature set to be larger than the first temperature threshold and equal to or lower than the target temperature of the power generation room. The fuel cell control device is set by the supply stop temperature according to at least one of the predetermined current change rate, the output current command corresponding to the target load, and the change width of the output current command. provide.

According to the present invention, when the temperature of the power generation chamber reaches a preset first temperature threshold, the supply of flammable gas to the air electrode is started, and the temperature of the power generation chamber is larger than the first temperature threshold of the power generation chamber. When the supply stop temperature set below the target temperature is reached, the supply of flammable gas to the air electrode is stopped. In this way, the supply of flammable gas to the air electrode is stopped before the temperature of the power generation room reaches the target temperature of the power generation room. Therefore, after the supply of flammable gas is stopped, the temperature of the power generation room is generated only by the heat generated by the power generation. Will be raised. As a result, the temperature of the power generation room can be quickly raised to the first temperature threshold value, and then gradually raised to the target temperature of the power generation room, and overshoot can be suppressed, and the power generation room can be recooled by overshoot. Can be suppressed.
Further, the supply stop temperature is set according to at least one of a predetermined current change rate used when setting the output current command, an output current command corresponding to the target load, and a change width of the output current command. Therefore, it is possible to set the supply stop temperature to an appropriate temperature according to the state of load increase. Here, the current change rate indicates the gradient of the amount of current change per hour, and the change width indicates the increase width of the current value in the output current command.

The present invention is a fuel cell control device including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged, and a target load setting unit for setting a target load and a target load setting unit. Using the output current command setting unit that sets the output current command of the fuel cell from the target load using a predetermined first current change rate, and the output current command set by the output current command setting unit, the said The output current command setting unit includes a control command setting unit that sets control commands to a plurality of control systems for changing the load of the fuel cell, and the output current command setting unit has a target output current in which the output current command corresponds to the target load. When the current threshold set below is reached, or when the power generation chamber temperature reaches a predetermined temperature threshold set below the target temperature of the power generation chamber, the value is set to a value smaller than the first current change rate. The output current command is set by using the second current change rate, and the current threshold or the temperature threshold provides a control device for a fuel cell in which the current threshold or the temperature threshold is set according to the first current change rate.

According to the present invention, when the output current command reaches the current threshold set below the target output current corresponding to the target load, or when the power generation chamber temperature reaches a predetermined temperature threshold set below the target power generation chamber temperature. When it reaches, the output current command is set using the second current change rate set to a value smaller than the first current change rate, so the output current command is quickly raised to the current threshold or temperature threshold, and then the target output current. The target output current can be set gently toward. As a result, it is possible to reduce the tracking delay that occurs when the output current command is set at the first current change rate, and it is possible to gradually increase each control amount toward the target output current. .. As a result, it is possible to suppress overshoot of the temperature of the power generation chamber, and it is possible to suppress recooling of the power generation chamber due to overshoot. Further, since the current threshold value or the temperature threshold value is set according to the first current change rate, it is possible to set these threshold values at an appropriate temperature according to the state of load increase.

In the fuel cell control device, the output current command setting unit is used when a predetermined time has elapsed after the output current command reaches the current threshold value, or when a predetermined time has passed since the power generation chamber temperature reaches the temperature threshold value. When the lapse has passed, the output current command may be set using the third current change rate set to be larger than the second current change rate.
Further, in the fuel cell control device, the second current change rate may be set to zero.

As a result, when the output current command reaches the current threshold set below the target output current corresponding to the target load, or when the power generation chamber temperature reaches the predetermined temperature threshold set below the target power generation chamber temperature. In the meantime, since the load increase is stopped or decelerated by using the second current change rate, the response of the control amount of each control system can catch up with the output current command during this period. Then, after a predetermined period of time has elapsed from the start of setting the output current command using the second current change rate, the output current command is set using the third current change rate set larger than the second current change rate. , It is possible to gradually increase the output current command toward the target output current. This makes it possible to suppress overshoot.

In the fuel cell control device, the target load setting unit may set the target load of the fuel cell from the outside air temperature around the fuel cell.

As a result, changes in the temperature of the power generation chamber such as changes in the amount of air supplied from the MGT compressor due to the outside air temperature can be suppressed, and stable temperature control can be performed.

When the power generation chamber temperature reaches a preset first temperature threshold, the fuel cell control device starts supplying flammable gas to the air electrode, and the power generation chamber temperature becomes the first temperature. A flammable gas flow control unit that stops the supply of the flammable gas to the air electrode when the supply stop temperature set above the threshold value and below the target temperature of the power generation room is reached is further provided, and the supply stop temperature is set. , The predetermined current change rate, the output current command corresponding to the target load, and the change width of the output current command may be set according to at least one of them.

In the fuel cell control device, the supply stop temperature is set to a lower value as the change width of the predetermined current change rate, the output current command corresponding to the target load, or the output current command is larger. May be good.

According to the above configuration, the supply stop temperature can be set to a lower value as the temperature of the power generation chamber is more likely to overshoot. As a result, overshoot of the temperature of the power generation chamber can be suppressed more reliably.

In the fuel cell control device, the plurality of control systems include fuel gas supply flow rate to the fuel electrode, fuel cell air electrode inlet temperature, micro gas turbine output, differential pressure between the fuel electrode and the air electrode, and recirculation. Two or more of the blower rotation speed and the pure water flow rate may be included.

In the fuel cell control device, the fuel cell is, for example, a solid oxide fuel cell.

The present invention provides a fuel cell including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged, and a power generation system including the fuel cell control device according to any one of the above. provide.

The power generation system includes a plurality of temperature measuring units provided in the central region of the power generation chamber, and the maximum temperature among the plurality of measured temperatures measured by the temperature measuring unit is used as the power generation chamber temperature. May be good.

In this way, detailed temperature information in the power generation chamber can be grasped by measuring the temperature by a plurality of temperature measuring units provided in the central region where the temperature is highest in the power generation chamber. Then, by using the highest temperature among the measured temperatures as the power generation room temperature, it is possible to control the power generation room temperature from the safety side by preventing a part of the power generation room from exceeding the upper limit temperature, and the power generation room temperature can be adjusted. It is possible to suppress damage to the equipment due to exceeding the upper limit.

The present invention is a method for controlling a fuel cell including a power generation chamber in which a plurality of power generation cells including a fuel pole, a solid electrolyte, and an air pole are arranged, and a predetermined measurement point provided in the power generation chamber. A temperature measurement process for measuring temperature, a target load setting process for setting a target load, a current command setting process for setting an output current command for the fuel cell from the target load using a predetermined rate of change, and the output. A control command setting process for setting control commands to a plurality of control systems for changing the load of the fuel cell using a current command, and a power generation room temperature specified from the measured temperatures measured in the temperature measurement process. Is set to a supply start step of supplying a flammable gas to the air electrode when the first temperature threshold is reached, and the power generation chamber temperature is larger than the first temperature threshold and equal to or lower than the power generation chamber target temperature. The supply stop step includes a supply stop step of stopping the supply of the flammable gas to the air electrode when the supplied stop temperature is reached, and the supply stop temperature corresponds to the predetermined current change rate and the target load. Provided is a fuel cell control method set according to at least one of an output current command and a change width of the output current command.

The present invention is a method for controlling a fuel cell including a power generation chamber in which a plurality of power generation cells including a fuel pole, a solid electrolyte, and an air pole are arranged, and a predetermined measurement point provided in the power generation chamber. A temperature measurement process for measuring the temperature, a target load setting process for setting the target load, and an output current command setting process for setting the output current command of the fuel cell from the target load using a predetermined first current change rate. And a control command setting step of setting a control command to a plurality of control systems for changing the load of the fuel cell by using the output current command, the output current command setting step includes the output current. When the command reaches a current threshold set below the target output current corresponding to the target load, or when the power generation chamber temperature reaches a predetermined temperature threshold set below the target power generation chamber temperature, the first The output current command is set using the second current change rate set to a value smaller than the first current change rate, and the current threshold or the temperature threshold is set according to the first current change rate. A method for controlling a battery is provided.

According to the present invention, when the load of the fuel cell increases, it is possible to shorten the time required to reach the target while suppressing the overshoot of the controlled amount.

It is a schematic block diagram which showed the schematic structure of the power generation system which concerns on one Embodiment of this invention. It is a figure which showed one aspect of the cell stack of SOFC which concerns on one Embodiment of this invention. It is a figure which showed one aspect of the SOFC module which concerns on one Embodiment of this invention. It is sectional drawing of one aspect of the SOFC cartridge which concerns on one Embodiment of this invention. It is a functional block diagram which expanded and showed the function provided with the control device which concerns on one Embodiment of this invention. It is a functional block diagram which expanded and showed the function in the 2nd temperature rise mode and the load rise mode of the SOFC control apparatus which concerns on one Embodiment of this invention. It is a figure which showed the schematic structure of the load increase control part shown in FIG. It is a figure which showed an example of the target load information. It is a figure for demonstrating the current threshold. It is a figure which showed an example of the fuel gas flow rate information. It is a figure which showed an example of the inlet air temperature information. It is a figure which showed an example of MGT output information. It is a figure which showed an example of the differential pressure information. It is a figure which showed an example of the rotation speed information. It is a figure which showed an example of pure water flow rate information. It is a flowchart which showed the control procedure which is executed by the load rise control part which concerns on one Embodiment of this invention. It is a figure for demonstrating the control and effect executed by the load increase control part which concerns on one Embodiment of this invention. It is a figure which showed the schematic structure of the temperature rise control part shown in FIG. It is a figure which showed an example of the 2nd fuel gas information. It is a flowchart which showed an example of the setting procedure of the supply stop temperature. It is a figure for demonstrating the control and effect executed by the temperature rise control part which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of a fuel cell control device and a control method and a power generation system according to the present invention will be described with reference to the drawings.

[Power generation system configuration]
First, a schematic configuration of a power generation system according to an embodiment of the present invention will be described.
FIG. 1 is a schematic configuration diagram showing a schematic configuration of a power generation system 10 according to an embodiment of the present invention. As shown in FIG. 1, the power generation system 10 includes a micro gas turbine (hereinafter referred to as “MGT”) 11, a generator 12, and SOFC 13. The power generation system 10 is configured to obtain high power generation efficiency by combining power generation by the MGT 11 and power generation by the SOFC 13.

The MGT 11 has a compressor 21, a combustor 22, and a turbine 23, and the compressor 21 and the turbine 23 are integrally rotatably connected by a rotating shaft 24. The compressor 21 is rotationally driven by the rotation of the turbine 23, which will be described later. The compressor 21 compresses the air A taken in from the air take-in line 25.
Compressed air (hereinafter, simply referred to as “air”) A1 from the compressor 21 is supplied to the combustor 22 via the first air supply line 26, and fuel is supplied via the first fuel gas supply line 27. Gas L1 is supplied. The first air supply line 26 is provided with a control valve 65 for adjusting the amount of air supplied to the combustor 22, and the first fuel gas supply line 27 adjusts the flow rate of fuel gas supplied to the combustor 22. A control valve 70 is provided for this purpose. Further, a part of the exhaust fuel gas L3 circulating in the fuel gas recirculation line 49 of the SOFC 13 described later is supplied to the combustor 22 through the exhaust fuel gas supply line 45. The exhaust fuel gas supply line 45 is provided with a control valve 47 for adjusting the amount of exhaust fuel gas supplied to the combustor 22. Further, a part of the exhaust air A2 used in the air electrode 13B of the SOFC 13 is supplied to the combustor 22 through the exhaust air supply line 36 described later.

The combustor 22 mixes and burns the fuel gas L1, a part of the air A, the exhaust fuel gas L3, and the exhaust air A2 to generate the combustion gas G. The combustion gas G is supplied to the turbine 23 through the combustion gas supply line 28. The turbine 23 rotates due to the adiabatic expansion of the combustion gas G, and the exhaust gas is discharged from the combustion exhaust gas line 55. The generator 12 is provided coaxially with the turbine 23, and generates electricity by rotationally driving the turbine 23.

Fuel gas L2 to the fuel gas L1 and later supplied to the combustor 22 is a combustible gas, for example, liquefied natural gas (LNG), city gas, hydrogen _{(H 2)} and carbon monoxide (CO), methane (CH Hydrocarbon gas such as ₄ ) and gas produced by gasification equipment for carbonaceous raw materials (oil, coal, etc.) are used.

The SOFC 13 is supplied with the heated fuel gas L2 as a reducing agent and the heated air (oxidizing agent gas) as an oxidizing agent gas, and reacts at a predetermined operating temperature to generate power. The SOFC 13 is configured by accommodating a fuel electrode 13A, an air electrode 13B, and a solid electrolyte in a pressure vessel. The detailed configuration of SOFC 13 will be described later.
The SOFC 13 generates electricity by supplying an oxidant gas to the air electrode 13B and supplying the fuel gas to the fuel electrode 13A. The oxidant gas is, for example, a gas containing approximately 15% to 30% of oxygen, and air is typically preferable. However, in addition to air, a mixed gas of combustion exhaust gas and air or a mixed gas of oxygen and air is used. Etc. can be used. In the present embodiment, a case where at least a part of air A compressed by the compressor 21 is adopted as the oxidant gas supplied to the SOFC 13 will be illustrated and described.

Air A1 is supplied to the SOFC 13 as an oxidant gas through the second air supply line 31 branched from the first air supply line 26 to the air supply section which is the introduction section of the air electrode 13B. The second air supply line 31 is provided with a control valve 64 for adjusting the flow rate of the supplied air A1. Further, in the first air supply line 26, a heat exchanger 58 is provided on the upstream side (in other words, the compressor 21 side) of the air A1 from the branch point of the second air supply line 31. In the heat exchanger 58, the air A is heat-exchanged with the exhaust gas discharged from the combustion exhaust gas line 55 to raise the temperature. Further, the second air supply line 31 is provided with a bypass line 62 that bypasses the heat exchanger 58. The bypass line 62 is provided with a control valve 66 so that the bypass flow rate of the air A can be adjusted. By controlling the opening degree of the control valves 64 and 66 by the control device 60 described later, the flow rate ratio between the air A passing through the heat exchanger 58 and the air A bypassing the heat exchanger 58 is adjusted, and the air A is adjusted. The temperature of the air A1 supplied to the SOFC 13 is adjusted through the second air supply line 31 which is a part of the above.
The temperature of the air A1 supplied to the SOFC 13 has an upper limit of the temperature so as not to damage the constituent materials of the SOFC cartridge 203, including the air supply unit for introducing the air A1 into the SOFC cartridge 203 constituting the SOFC 13 and the air supply branch pipe. It is restricted.

Further, an air electrode fuel supply line 80 for supplying the fuel gas L2 as a flammable gas is connected to the second air supply line 31. The air electrode fuel supply line 80 is provided with a control valve 82 for adjusting the amount of fuel gas supplied to the second air supply line 31. By controlling the valve opening degree of the control valve 82 by the control device 60 described later, the supply amount of the fuel gas L2 added to the air A1 is adjusted. The amount of the fuel gas L2 added to the air A1 is supplied at a flammable limit concentration or less, and more preferably at 3% by volume or less.

An exhaust air discharge line 34 for discharging the exhaust air A2 used in the air electrode 13B is connected to the SOFC 13. An exhaust air supply line 36 for supplying exhaust air A2 to the combustor 22 is connected to the exhaust air discharge line 34. The exhaust air supply line 36 is provided with a shutoff valve 38 for disconnecting the system between the SOFC 13 and the task turbine 11.
Further, the exhaust air discharge line 34 is provided with a control valve (or shutoff valve) 37 for adjusting the amount of exhaust air discharged to the outside.

The SOFC 13 is further subjected to a second fuel gas supply line 41 for supplying the fuel gas L2 to the fuel gas supply unit 207 (see FIG. 3) which is an introduction unit of the fuel electrode 13A, and after being used for the reaction at the fuel electrode 13A. It is connected to the exhaust fuel gas line 43 that discharges the exhaust fuel gas L3. The second fuel gas supply line 41 is provided with a control valve 42 for adjusting the flow rate of the fuel gas L2 supplied to the fuel electrode 13A, and the exhaust fuel gas line 43 adjusts the amount of exhaust fuel gas discharged to the outside. A control valve (or shutoff valve) 46 is provided for this purpose. The excess pressure can be quickly adjusted by the control valve (or shutoff valve) 46 of the exhaust fuel gas line 43 and the control valve (or shutoff valve) 37 of the exhaust air discharge line 34. Further, the fuel air differential pressure between the fuel electrode 13A and the air electrode 13B of the SOFC 13 is controlled by the control valve 47 so that the fuel electrode 13A side becomes higher in a predetermined pressure range. Further, a fuel gas recirculation line 49 for recirculating the exhaust fuel gas L3 to the inlet of the fuel electrode 13A of the SOFC 13 is connected to the exhaust fuel gas line 43. The fuel gas recirculation line 49 is provided with a recirculation blower 50 for recirculating the exhaust fuel gas L3.

Further, the fuel gas recirculation line 49 is provided with a pure water supply line 44 for supplying pure water for reforming the fuel gas L2 to the fuel electrode 13A. A pump 48 is provided on the pure water supply line 44. The amount of pure water supplied to the fuel electrode 13A is adjusted by controlling the discharge flow rate of the pump 48 by the control device 60.

[SOFC configuration]
Next, the configuration of the SOFC 13 will be described with reference to FIGS. 2 to 4.
First, a cylindrical cell stack used for SOFC of the SOFC combined cycle power generation system (fuel cell combined cycle power generation system) according to the present embodiment will be described with reference to FIG. FIG. 2 is a diagram showing one aspect of the cell stack 101 according to the present embodiment. The cell stack 101 includes a cylindrical base tube 103, a plurality of fuel cell 105 formed on the outer peripheral surface of the base tube 103, and an interconnector 107 formed between adjacent fuel cell 105. The fuel cell 105 is formed by laminating a fuel electrode 13A, a solid electrolyte 111, and an air electrode 13B. Further, the cell stack 101 is an air electrode 13B of the fuel cell 105 formed at one end of the plurality of fuel cell 105 formed on the outer peripheral surface of the base pipe 103 in the longitudinal axis direction of the base pipe 103. A lead film 115 electrically connected to the fuel cell 105 via an interconnector 107, and electrically connected to a fuel electrode 109 of a fuel cell 105 formed at the other end of the end (not shown). To be equipped.

Substrate tube 103 is made of a porous material, for example, CaO-stabilized _ZrO 2 (CSZ), a mixture of CSZ and nickel oxide (NiO) (CSZ + NiO) , or _Y 2 _{O 3} stabilized ZrO ₂ (YSZ), or The main component is MgAl ₂ O _{4 and the} like. The base tube 103 supports the fuel cell 105, the interconnector 107, and the lead film 115, and the fuel gas supplied to the inner peripheral surface of the base tube 103 is supplied to the inner peripheral surface of the base tube 103 through the pores of the base tube 103. It is diffused into the fuel electrode 13A formed on the outer peripheral surface of the.

The fuel electrode 13A is composed of an oxide of a composite material of Ni and a zirconia-based electrolyte material, and for example, Ni / YSZ is used. The thickness of the fuel electrode 109 is 50 to 250 μm. In this case, in the fuel electrode 13A, Ni, which is a component of the fuel electrode 13A, has a catalytic action on the fuel gas. This catalytic action reacts a fuel gas supplied via the substrate tube 103, for example, a mixed gas of methane (CH ₄ ) and water vapor, and reforms it into hydrogen (H ₂ ) and carbon monoxide (CO). .. Further, the fuel electrode 13A is an interface between hydrogen (H ₂ ) and carbon monoxide (CO) obtained by reforming and oxygen ions (O ^2- ) supplied via the solid electrolyte 111 with the solid electrolyte 111. It reacts electrochemically in the vicinity to produce water (H ₂ O) and carbon dioxide (CO ₂ ). At this time, the fuel cell 105 generates electricity by the electrons emitted from the oxygen ions. The fuel gas L2 that can be supplied and used for the fuel electrode 13A of SOFC 13 is hydrocarbon gas such as hydrogen (H ₂ ), carbon monoxide (CO), and methane (CH ₄ ), city gas, natural gas, as well as oil. It is operated using gas produced from carbonaceous raw materials such as methanol and coal gas by a gasification facility as fuel. As the fuel gas L2 in the present embodiment, for example, city gas is used, and a fuel gas containing methane as a main component is used.

The solid electrolyte 111 is mainly composed of YSZ having airtightness that does not allow gas to pass through and high oxygen ion conductivity at high temperature. The solid electrolyte 111 moves oxygen ions (O ^2- ) generated at the air electrode 13B to the fuel electrode. The film thickness of the solid electrolyte 111 located on the surface of the fuel electrode 13A is 10 to 100 μm.

The air electrode 13B is composed of, for example, a LaSrMnO _3- based oxide or a LaCoO _3- based oxide. The air electrode 13B dissociates oxygen in the supplied oxidant gas such as air in the vicinity of the interface with the solid electrolyte 111 to generate oxygen ions (O ^2- ). The air electrode 13B may have a two-layer structure. In this case, the air electrode layer (air electrode intermediate layer) on the solid electrolyte 111 side is made of a material showing high ionic conductivity and excellent catalytic activity. The air electrode layer (air electrode conductive layer) on the air electrode intermediate layer may be composed of a perovskite-type oxide represented by Sr and Ca-doped LaMnO ₃ . By doing so, the power generation performance can be further improved.

The interconnector 107 is composed of a conductive perovskite-type oxide represented by M _1-x L _x TiO ₃ (M is an alkaline earth metal element and L is a lanthanoid element) such as SrTiO ₃ system. The interconnector 107 has a dense film so that the fuel gas and air do not mix with each other, and has stable durability and electrical conductivity in both an oxidizing atmosphere and a reducing atmosphere. In the adjacent fuel cell 105, the interconnector 107 electrically connects the air electrode 13B of one fuel cell 105 and the fuel electrode 13A of the other fuel cell 105, and the adjacent fuel cell 105 are connected to each other. Are connected in series. Since the lead film 115 needs to have electron conductivity and a coefficient of thermal expansion close to that of other materials constituting the cell stack 101, Ni such as Ni / YSZ and a zirconia-based electrolyte material are used. It is composed of a composite material. The lead film 115 derives the DC power generated by the plurality of fuel cell 105s connected in series by the interconnector to the vicinity of the end of the cell stack 101.

Next, the SOFC module and the SOFC cartridge according to the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a view showing one aspect of the SOFC module according to the present embodiment, and FIG. 4 is a cross-sectional view of one aspect of the SOFC cartridge according to the present embodiment.

As shown in FIG. 3, the SOFC module 201 includes, for example, a plurality of SOFC cartridges 203 and a pressure vessel 205 for accommodating the plurality of SOFC cartridges 203. Although FIG. 3 illustrates a cylindrical SOFC cell stack, this does not necessarily have to be the case, and for example, a flat cell stack may be used. Since the pressure vessel 205 is operated at an internal pressure of 0.1 MPa to about 1 MPa and an internal temperature of atmospheric temperature to about 550 ° C., it has a proof stress and corrosion resistance to an oxidant gas such as oxygen contained in the oxidizing gas. The material that owns is used. For example, a stainless steel material such as SUS304 is suitable.

The SOFC module 201 includes a fuel gas supply unit 207 and a plurality of fuel gas supply branch pipes 207a, and a fuel gas discharge unit 209 and a plurality of fuel gas discharge branch pipes 209a. Further, the SOFC module 201 includes an air supply unit (not shown), an air supply branch pipe (not shown), an air discharge unit (not shown), and a plurality of air discharge branch pipes (not shown).

The fuel gas L2 from the second fuel gas supply line 41 (see FIG. 1) is supplied to the plurality of SOFC cartridges 203 through the fuel gas supply unit 207 and the plurality of fuel gas supply branch pipes 207a. The fuel gas supply branch pipe 207a guides the fuel gas L2 supplied through the fuel gas supply unit 207 to the plurality of SOFC cartridges 203 at a substantially equal flow rate, and substantially equalizes the power generation performance of the plurality of SOFC cartridges 203.

The exhaust fuel gas L3 discharged from the SOFC cartridge 203 is guided to the exhaust fuel gas line 43 (see FIG. 1) at a substantially equal flow rate by passing through the fuel gas discharge branch pipe 209a and the fuel gas discharge unit 209.

In the present embodiment, a mode in which a plurality of SOFC cartridges 203 are assembled and stored in the pressure vessel 205 is described, but the present invention is not limited to this, and for example, the SOFC cartridge 203 is not assembled and is stored in the pressure vessel 205. It may be stored inside.

As shown in FIG. 4, the SOFC cartridge 203 includes a plurality of cell stacks 101, a power generation chamber 215, a fuel gas supply chamber 217, a fuel gas discharge chamber 219, an air supply chamber 221 and an air discharge chamber 223. I have. Further, the SOFC cartridge 203 includes an upper tube plate 225a, a lower tube plate 225b, an upper heat insulating body 227a, and a lower heat insulating body 227b. In the present embodiment, the SOFC cartridge 203 is provided with the fuel gas by arranging the fuel gas supply chamber 217, the fuel gas discharge chamber 219, the air supply chamber 221 and the air discharge chamber 223 as shown in FIG. The structure is such that air as an oxidant gas flows opposite to the inside and outside of the cell stack 101, but the embodiment is not necessarily limited to this example, and for example, the inside and outside of the cell stack are parallel to each other. Or air may flow in a direction orthogonal to the longitudinal axis of the cell stack.

The power generation chamber 215 is a region formed between the upper heat insulating body 227a and the lower heat insulating body 227b. The power generation chamber 215 is an area in which the fuel cell 105 of the cell stack 101 is arranged, and is an area in which fuel gas and air are electrochemically reacted to generate electricity. For example, the temperature near the central portion of the cell stack 101 in the power generation chamber 215 in the longitudinal direction is monitored by a temperature sensor 92 or the like, which will be described later, and becomes a high temperature atmosphere of about 700 ° C. to 1000 ° C. during steady operation of the SOFC module 201.

The fuel gas supply chamber 217 is an area surrounded by the upper casing 229a and the upper pipe plate 225a of the SOFC cartridge 203, and the fuel gas supply branch pipe 207a is provided by the fuel gas supply hole 231a provided in the upper part of the upper casing 229a. Is communicated with. The plurality of cell stacks 101 are joined to the upper pipe plate 225a by the seal member 237a, and the fuel gas supply chamber 217 receives the fuel gas supplied from the fuel gas supply branch pipe 207a through the fuel gas supply hole 231a. It is guided inside the base tubes 103 of the plurality of cell stacks 101 at a substantially uniform flow rate, and the power generation performance of the plurality of cell stacks 101 is substantially made uniform.

The fuel gas discharge chamber 219 is an area surrounded by the lower casing 229b and the lower pipe plate 225b of the SOFC cartridge 203, and the fuel gas discharge branch pipe 209a is provided by the fuel gas discharge hole 231b provided in the lower part of the lower casing 229b. Is communicated with. The plurality of cell stacks 101 are joined by a lower pipe plate 225b and a sealing member 237b, and the fuel gas discharge chamber 219 passes through the inside of the base pipe 103 of the plurality of cell stacks 101 and is supplied to the fuel gas discharge chamber 219. The exhaust fuel gas L3 to be generated can be aggregated and guided to the fuel gas discharge branch pipe 209a through the fuel gas discharge hole 231b.

The air supply chamber 221 is an area surrounded by the lower casing 229b, the lower pipe plate 225b, and the lower heat insulating body 227b of the SOFC cartridge 203, and is illustrated by the air supply hole 233a provided on the side surface of the lower casing 229b. Not communicated with the air supply branch pipe. The air supply chamber 221 can guide a predetermined flow rate of air supplied from an air supply branch pipe (not shown) through the air supply hole 233a to the power generation chamber 215 through the air supply gap 235a at a substantially uniform flow rate.

The air discharge chamber 223 is an area surrounded by the upper casing 229a of the SOFC cartridge 203, the upper pipe plate 225a, and the upper heat insulating body 227a, and is illustrated by the air discharge holes 233b provided on the side surface of the upper casing 229a. It is communicated with the air discharge branch pipe. The air discharge chamber 223 can guide the exhaust air supplied from the power generation chamber 215 to the air discharge chamber 223 through the air discharge gap 235b to an air discharge branch pipe (not shown) through the air discharge hole 233b.

The DC power generated in the power generation chamber 215 is led out to the vicinity of the end of the cell stack 101 by a lead film 115 (see FIG. 2) made of Ni / YSZ or the like provided in the plurality of fuel cell 105, and then the SOFC cartridge. The current is collected by the current collecting rod (not shown) of 203 via the current collecting plate (not shown), and is taken out to the outside of each SOFC cartridge 203. The electric power led out to the outside of the SOFC cartridge 203 by the current collector rod is led out to the outside of the SOFC module 201, converted into predetermined AC power by an inverter (not shown) or the like, and supplied to the power load.

As described above, in the SOFC 13 according to the present embodiment, the fuel gas L2 and the air A1 flow so as to face the inside and the outside of the cell stack 101. As a result, the exhaust air A2 exchanges heat with the fuel gas L2 supplied to the power generation chamber 215 through the inside of the base pipe 103, and the upper pipe plate 225a and the like made of a metal material are deformed such as buckling. It is cooled to a temperature that does not allow it to be supplied to the air discharge chamber 223. Further, the fuel gas L2 is heated by heat exchange with the exhaust air A2 discharged from the power generation chamber 215 and supplied to the power generation chamber 215. As a result, the fuel gas L2 preheated to a temperature suitable for power generation can be supplied to the power generation chamber 215 without using a heater or the like. Further, the exhaust fuel gas L3 that has passed through the inside of the base pipe 103 and passed through the power generation chamber 215 is heat-exchanged with the air A1 supplied to the power generation chamber 215, and the lower pipe plate 225b and the like made of a metal material are formed. It is cooled to a temperature at which it does not deform such as buckling and is supplied to the fuel gas discharge chamber 219. Further, the air A1 is heated by heat exchange with the exhaust fuel gas L3 and supplied to the power generation chamber 215. As a result, air heated to a temperature required for power generation can be supplied to the power generation chamber 215 without using a heater or the like.

Further, as shown in FIG. 4, at least one or more temperature sensors 92 are arranged in each SOFC cartridge 203. For example, when the SOFC 13 is configured to include four SOFC cartridges 203, at least a total of four temperature sensors will be provided. The temperature sensor 92 is arranged at least in the central region of the cell stack 101 in the power generation chamber 215 in the longitudinal direction. The central region in the present embodiment is a region including the position where the temperature becomes the highest when the temperature distribution in the longitudinal direction of the cell stack 101 is taken, and the lower portion of the cell stack 101 is 0% and the upper portion is 100%. In the case, it is in the range of about 30% to 65%. More preferably, the central region is in the range of about 45% to 55%.
Further, the SOFC 13 is provided with various sensors such as a differential pressure sensor 90 (see FIG. 1) that measures the differential pressure between the fuel pole 13A and the air pole 13B. The measured values of the various sensors 90 and 92 provided at each part of the SOFC 13 are transmitted to the control device 60.

Further, the power generation system 10 is provided with an outside air temperature sensor 94 (see FIG. 1) that measures the outside air temperature around the SOFC 13. In the present embodiment, the outside air temperature sensor 94 is provided near the suction port of the compressor 21 of the MGT 11 and measures the temperature of the air A sucked by the compressor 21. The measured value of the outside air temperature sensor 94 is transmitted to the control device 60.

Further, the power generation system 10 includes a temperature sensor (not shown) that measures the air temperature (inlet air temperature) supplied to the SOFC 13 through the second air supply line 31, and the exhaust gas L3 that circulates in the fuel gas recirculation line 49. A temperature sensor (not shown) or the like for measuring the temperature of the air is provided. The measured value of each temperature sensor is transmitted to the control device 60.

The control device 60 acquires measured values from various sensors, opening degree information of each control valve, and the like, performs calculations based on the acquired information, and controls the operation of each part of the power generation system 10.

[How to operate the power generation system]
Next, in the power generation system 10 having the above configuration, the control executed by the control device 60 will be briefly described.

At the time of starting the power generation system 10, the control device 60 first starts the MGT 11, stabilizes the output of the MGT 11 with a certain load, and then supplies a part of the air supplied from the compressor 21 to the SOFC 13. Then, the air electrode 13B of the SOFC 13 can be pressurized. Further, the fuel electrode 13A is pressurized by using a mixed gas or the like in which a reducing gas such as H ₂ is added to an inert gas such as N ₂ until the temperature rises to a predetermined temperature at which the reforming reaction of the fuel gas is possible. I can go. Further, the temperature of the air A1 supplied to the air electrode 13B of the SOFC 13 is raised to 300 to 500 ° C. by the heat exchanger 58, and the air electrode is such that the combustion reaction of the fuel gas L2 added to the air A1 occurs. The temperature of the power generation chamber 215 can be raised to a temperature at which 13B functions as a catalyst. When the SOFC 13 is pressurized to a predetermined pressure, the shutoff valve 38 is opened to connect the SOFC 13 and the MGT 11, and the state shifts to a combined state in which air is supplied to the combustor 22 of the MGT 11 via the SOFC 13.

After the transition to the combined state, the air flow rate supplied to the SOFC 13 to raise the temperature of the SOFC 13 is increased, and the air flow rate supplied to the combustor 22 by bypassing the SOFC 13 is decreased. Then, until the SOFC 13 starts power generation after a certain period of time, the entire amount of air A is controlled to be supplied to the combustor 22 via the SOFC 13 so that the temperature of the SOFC 13 can be raised as quickly as possible at a uniform temperature. It may be.

Next, the control device 60 according to the embodiment of the present invention will be described with reference to the drawings.
The control device 60 is, for example, a computer or a sequencer, and includes a CPU, a ROM (Read Only Memory) for storing programs executed by the CPU, and a RAM (Random Access Memory) that functions as a work area during execution of each program. ) Etc. are provided. A series of processing processes for realizing various functions described later is recorded in a recording medium or the like in the form of a program, and the CPU reads this program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions described later are realized.

FIG. 5 is a functional block diagram showing an expanded function of the control device 60 according to the present embodiment. As shown in FIG. 5, the control device 60 includes an SOFC control device 60a for controlling the SOFC 13 and an MGT control device 60b for controlling the MGT 11. Information can be exchanged between the SOFC control device 60a and the MGT control device 60b.

When the SOFC 13 is started, the SOFC control device 60a executes the first temperature rise mode, the second temperature rise mode, and the load rise mode in order to raise the power generation chamber temperature to the rated temperature and raise the load to the target load. ..

First, in the first temperature raising mode, the temperature of the power generation chamber 215 is raised by supplying the air A1 heated by the heat exchange by the heat exchanger 58 to the air electrode 13B. When the temperature of the power generation chamber reaches the first temperature threshold value Tth1 by the first temperature raising mode, the first temperature rising mode is switched to the second temperature rising mode. Here, the first temperature threshold is a temperature at which the air electrode 13B functions as a catalyst for the combustion reaction with the fuel gas L2 as a flammable gas, and is set, for example, in the range of about 400 ° C. to 450 ° C. There is.

In the second temperature rising mode, the air A1 is supplied to the air electrode 13B as in the first temperature rising mode, and the fuel gas L2 is added to the air A1 by the air electrode fuel supply line 80 by opening the control valve 82. .. In the air electrode 13B into which the air A1 and the fuel gas L2 have flowed in, the fuel gas L2 is catalytically burned on the air electrode 13B by the catalytic action of the air electrode 13B, and combustion heat is generated. In this way, in the second temperature rising mode, the temperature of the power generation chamber is raised by using the heat generated by the catalyst combustion.
In the second temperature rising mode, the SOFC control device 60a controls the flow rate of the fuel gas L2 so that the temperature change rate of the power generation chamber temperature does not exceed the upper limit value. Further, the SOFC control device 60a controls the inlet air temperature of the air A1 supplied to the air electrode 13B of the SOFC 13 by the control valve 66 of the bypass line 62 according to the temperature of the power generation chamber.
When the power generation chamber temperature reaches the second temperature threshold value Tth2, the SOFC control device 60a switches from the second temperature rise mode to the load increase mode.

In the load increase mode, it is possible to raise the temperature of the power generation room only by self-heating due to the power generation during the load increase, but since it takes a long time to raise the temperature, the air electrode is the same as in the first temperature rise mode. Air A1 is supplied to 13B, and fuel gas L2 and pure water supply line 44 are supplied to the fuel electrode 13A from the second fuel gas supply line 41 to start power generation. In the load increase mode, the temperature of the power generation chamber is raised by both the heat generated by the catalyst combustion by supplying the fuel gas L2 to the air electrode 13B and the heat generated by the power generation. In the load increase mode, after the temperature of the power generation room of the SOFC 13 rises until the temperature can be maintained by self-heating due to power generation, the supply amount of the fuel gas L2 supplied to the air electrode 13B is gradually reduced. The supply of the fuel gas L2 to the air electrode 13B is controlled to be zero at the same time when the load is reached. Further, in the load increase mode, the temperature of the power generation chamber rises due to the catalytic combustion of the air electrode and the heat generated by applying a load to the SOFC 13, but the temperature of the power generation chamber rises later than the load rise.

The second temperature threshold value Tth2 is set to, for example, 750 ° C. or higher. This is because if the fuel gas L2 is charged to the fuel electrode 13A side when the fuel cell 105 has not reached a sufficient temperature, the fuel cell when the solid electrolyte 111 (see FIG. 2) is in a high resistance state. This is because when the 105 is generated, the electrode constituent material is structurally changed and deteriorated, which causes a deterioration in the performance of the fuel cell 105. If the power generation chamber temperature is 750 ° C. or higher, the performance deterioration of the fuel cell 105 as described above is unlikely to occur. Therefore, the second temperature threshold value Tth2 is preferably set to around 750 ° C.
In the load increase mode, when the power generation room temperature reaches the power generation room target temperature Ttag and the load reaches the target load such as the rated load, the start-up is completed. The target temperature Ttag of the power generation room is equal to or higher than the temperature at which the SOFC 13 can maintain the temperature by self-heating due to the heat generated by the power generation, and is set at, for example, 800 to 950 ° C.

Next, the control at startup executed by the SOFC control device 60a will be specifically described with reference to the drawings. Here, a second temperature rising mode and a load rising mode, which are characteristic parts of the present invention, will be described in particular.

FIG. 6 is a functional block diagram showing the functions of the SOFC control device 60a according to the embodiment of the present invention in the second temperature rising mode and the load rising mode.
As shown in FIG. 6, the SOFC control device 60a includes a load increase control unit 4 and a temperature increase control unit 5.

First, the load increase control unit 4 will be described. As shown in FIG. 7, the load increase control unit 4 includes a target load setting unit 51, an output current command setting unit 52, a control command setting unit 53, and a control unit 54. The target load setting unit 51 has target load information in which the outside air temperature and the target load (= target output current) of the SOFC 13 are associated with each other. The target load setting unit 51 acquires the value of the target load corresponding to the outside air temperature measured by the outside air temperature sensor 94 from the target load information and sets it as the target load.

FIG. 8 is a diagram showing an example of target load information. In FIG. 8, the horizontal axis represents the outside air temperature, and the vertical axis represents the target load (= target output current). The target load information is, for example, created in advance based on the results of a simulation or an actual machine test, and is supplied to the air electrode 13B when the valve opening of the control valve 65 is fully closed. When the flow rate of the air A1 is set to the maximum, the value of the maximum load (maximum output current) that the SOFC 13 can output is set in association with the outside air temperature. When the valve opening degree of the control valve 65 or the like is the same, in other words, when the flow rate is the same but the outside air temperature is different, the amount of air supplied to the power generation chamber 215 of the SOFC 13 changes because the air density changes. For example, when the outside air temperature is low, the air density becomes high, and the discharge air flow rate of the compressor 21 of the MGT 11 increases. Since the air A1 supplied to the power generation chamber 215 functions as a coolant, the larger the amount of air, the larger the maximum load that the SOFC 13 can output. For this reason, as shown in FIG. 7, the target load information has a characteristic that the lower the outside air temperature, the larger the target load.

Further, as shown by the dotted line in FIG. 8, the target load information may have a predetermined margin with respect to the target load determined from the outside air temperature. When the temperature of the power generation chamber changes due to a change in the load of the SOFC 13, the temperature of the power generation chamber may have a temperature distribution. By providing a predetermined margin in this way, it is possible to prevent the temperature of a part of the power generation chamber from exceeding the temperature upper limit value determined from the heat resistant temperature of some members of the SOFC 13 as much as possible. .. In the present embodiment, the margin here is set in the range of about 0.5% or less with respect to the target load (= target output current), for example. If the margin exceeds 0.5% and further exceeds 1%, the current value reached with respect to the target load (= target output current) decreases, which is not preferable because it deviates from the purpose of increasing the output of SOFC13 as much as possible. .. Further, if it is less than 0.1%, it is not preferable because it falls within the control error range of a flow rate control device (mass flow controller, etc.) and does not have a substantial margin.

The output current command setting unit 52 sets the output current command at a predetermined repetition time interval at a predetermined current change rate based on the target output current determined from the target load. If the current change rate is not provided, the current will change instantaneously, the response of each control amount cannot be followed, the fuel gas will temporarily become excessive or deficient, and the operation of the power generation system 10 will become unstable. SOFC There is a possibility that the cartridge 203 will be damaged. Here, the current change rate indicates the gradient of the current change amount (current increase amount) per hour.
Specifically, the output current command setting unit 52 sets the output current command at the first current change rate (for example, 5% / min of the rated current) in the current range where the output current command is equal to or less than the current threshold, and outputs the output. When the current command reaches the current threshold, the second current change rate (for example, 0% (0A) / min of the rated current) set to zero or more and smaller than the first current change rate is set. The output current command is set by using the third current change rate (3rd current change rate), which is set to a value larger than the second current change rate after a predetermined period of time has elapsed after the output current command reaches the current threshold. For example, the output current command is set using 0.5% / min of the rated current).

The current threshold value is set according to the first current change rate. Specifically, as shown in FIG. 9, the difference ΔI corresponding to the first current change rate is acquired by using the information associated with the first current change rate and the difference ΔI. For example, when the first current change rate is set to 5% / min of the rated current, the difference α is acquired. Then, the current threshold value is obtained by subtracting this α from the target output current. That is, in this case, the current threshold value = (target output current −α) is set.
Further, the predetermined period is set according to the response delay of the power generation room temperature when the output current command is set at the first current change rate.

The control command setting unit 53 sets a plurality of control system control commands for changing the load of the SOFC 13 by using the output current command set by the output current command setting unit 52. Here, instead of issuing individual control commands and issuing the next control command after the changes in the power generation chamber temperature and output current, which are the control amounts, have stabilized, the control commands are issued almost at the same time. For example, the control command setting unit 53 sets the flow rate command of the fuel gas L2 supplied to the fuel electrode 13A, the first fuel gas flow rate setting unit 53a, and the inlet air for setting the inlet temperature command of the air A1 supplied to the air electrode 13B. Temperature setting unit 53b, MGT output setting unit 53c for setting MGT output command, differential pressure setting unit 53d for setting differential pressure command between fuel electrode 13A and air electrode 13B, recirculation blower 50 for setting rotation rate command It includes a circulation flow rate setting unit 53e and a pure water flow rate setting unit 53f for setting a flow rate command of pure water to be supplied to the fuel electrode 13A.

As shown in FIG. 10, for example, the first fuel gas flow rate setting unit 53a has the first fuel gas flow rate information in which the output current command and the flow rate of the fuel gas L2 are associated with each other, and the first fuel gas flow rate. The flow rate of the fuel gas L2 corresponding to the output current command is acquired from the information, and the acquired flow rate of the fuel gas L2 is set as the first fuel gas flow rate command.
As shown in FIG. 11, the inlet air temperature setting unit 53b has inlet air temperature information in which the output current command and the inlet air temperature of the SOFC 13 to the air electrode 13B are associated with each other, and the inlet air temperature information. The inlet air temperature corresponding to the output current command is acquired from, and the acquired inlet air temperature is set as the inlet air temperature command.
As shown in FIG. 12, the MGT output setting unit 53c has MGT output information in which the output current command and the MGT output are associated with each other, and acquires the MGT output corresponding to the output current command from the MGT output information. Then, the acquired MGT output is set as the MGT output command. Here, the MGT output information may be set according to the outside air temperature taken into the compressor 21 of the MGT 11. The outside air temperature is measured by, for example, the outside air temperature sensor 94. For example, the MGT output information is set so that the MGT output for the same output current command increases as the intake outside air temperature decreases. This is because the lower the outside air temperature, the higher the flow rate of the air A blown by the compressor 21, and the more the flow rate of the combustion gas G from the combustor 22 can be increased.

For example, as shown in FIG. 13, the differential pressure setting unit 53d has differential pressure information in which the output current command and the fuel air differential pressure, which is the differential pressure between the fuel pole 13A and the air pole 13B, are associated with each other. The fuel air differential pressure corresponding to the output current command is acquired from the differential pressure information, and the acquired fuel air differential pressure is set as the fuel air differential pressure command.
For example, as shown in FIG. 14, the recirculation flow rate setting unit 53e has rotation speed information associated with the output current command and the blower rotation speed, and discharges the fuel gas recirculation line 49 according to the blower rotation speed. The flow rate for recirculating a part of the fuel gas L3 is controlled. The blower rotation speed corresponding to the output current command is acquired from the rotation speed information, and the acquired blower rotation speed is set as the blower rotation speed command. Here, the rotation speed information may be set according to the outside air temperature taken in by the MGT. For example, as shown in FIG. 8, the SOFC target load changes depending on the outside air temperature. When the outside air temperature becomes low, the SOFC target load rises, so that the air flow rate supplied to the SOFC increases and the pressure inside the system rises. As a result, the recirculation gas density increases, so when the outside air temperature is low, the blower rotation speed required to achieve the same recirculation flow rate as when the outside air temperature is high is set to be low.

As shown in FIG. 15, for example, the pure water flow rate setting unit 53f has pure water flow rate information in which the output current command and the pure water flow rate are associated with each other, and corresponds to the output current command from the pure water flow rate information. Acquire the pure water flow rate and set the acquired pure water flow rate as the pure water flow rate command. When the output current is increased, the SOFC load increases, and the amount of water vapor supplied from the fuel gas recirculation line 49 also increases. Therefore, most of the steam required for reforming can be covered by the steam supplied from the fuel gas recirculation line 49, and the flow rate of pure water required to be supplied from the outside is reduced. Further, when the output current is equal to or higher than the predetermined SOFC load, all the steam required for reforming is supplied from the fuel gas recirculation line 49, so that the supply of pure water becomes unnecessary.

The control unit 54 includes a first fuel gas flow rate control unit 54a, an inlet air temperature control unit 54b, an MGT output control unit 54c, a differential pressure control unit 54d, a recirculation flow rate control unit 54e, and a pure water flow rate control unit 54f. ..
The first fuel gas flow rate control unit 54a controls the valve opening degree of the control valve 42 based on the first fuel gas flow rate command from the first fuel gas flow rate setting unit 53a, thereby supplying the fuel gas to the fuel electrode 13A. Adjust the amount.
The inlet air temperature control unit 54b adjusts the valve opening degrees of the control valves 64 and 66 based on the inlet air temperature command from the inlet air temperature setting unit 53b, so that the inlet temperature of the air A1 supplied to the air electrode 13B is adjusted. To control.
The MGT output control unit 54c controls the MGT output mainly by adjusting the valve openings of the control valve 65 and the control valve 70 based on the MGT output command from the MGT output setting unit 53c.

The differential pressure control unit 54d adjusts the valve opening degree of the control valve 47 provided in the exhaust fuel gas supply line 45 based on the fuel air differential pressure command from the differential pressure setting unit 53d, so that the fuel electrode 13A side is set. The fuel air differential pressure in the power generation chamber 215 is controlled so as to be higher in a predetermined range (for example, 0.1 to 1 kPa) from the air electrode 13B side.
The recirculation flow rate control unit 54e controls the amount of exhaust fuel gas supplied to the fuel electrode 13A by controlling the rotation speed of the recirculation blower 50 based on the blower rotation speed command from the recirculation flow rate setting unit 53e.
The pure water flow rate control unit 54f controls the amount of pure water supplied to the fuel electrode 13A by adjusting the discharge flow rate of the pump 48 based on the pure water flow rate command from the pure water flow rate setting unit 53f.

For at least two control systems of the first fuel gas flow rate control unit 54a, inlet air temperature control unit 54b, MGT output control unit 54c, differential pressure control unit 54d, recirculation flow rate control unit 54e, and pure water flow rate control unit 54f. On the other hand, control commands are issued almost at the same time. For example, feedback control and feedforward control are performed based on each input command to control various control amounts to match the control commands. Since known techniques may be appropriately applied to these controls, detailed description thereof will be omitted. For example, various manipulated variables in the control commands of various control systems may be created in advance based on the results of a simulation or an actual machine test using the characteristics shown in FIGS. 10 to 15. By doing so, even if control commands are issued to a plurality of control systems almost at the same time, each control amount stably approaches the command value under appropriate control, and the temperature of the power generation room of SOFC 13 and the like. It is possible to stably approach the load (output current) to the target value.

Next, the control in the load increase mode executed by the load increase control unit 4 will be described with reference to FIG. FIG. 16 is a flowchart showing a control procedure in the load increase mode. The load increase mode is a control mode that is started when the temperature of the power generation chamber reaches the second temperature threshold value Tth2 in the second temperature rise mode described above.

First, the target load setting unit 51 sets the target load (= target output current) from the target load information shown in FIG. 7 based on the outside air temperature (step SA1). Subsequently, the output current command setting unit 52 sets an output current command from the target output current corresponding to the target load using a predetermined current change rate (step SA2). Here, the predetermined current change rate changes according to the output current command. Specifically, when the output current command is equal to or less than the above-mentioned current threshold, the output current command is set using the first current change rate, and until a predetermined period elapses after the output current command reaches the current threshold. The output current command is set using the second current change rate, and the output current command is set using the third current change rate after a predetermined period has elapsed after the output current command reaches the current threshold. Here, the predetermined time is set to an appropriate value based on the result of a simulation or an actual machine test in consideration of the response delay of the temperature of the power generation room.

Subsequently, the control command setting unit 53 sets a control command for each control system based on the set output current command (step SA3). Then, the control unit 54 controls the operation amount of each control system based on the set various control commands at substantially the same time (step SA4). As a result, the control amount of various control systems changes toward the target load at about the same time. Subsequently, it is determined whether or not the output current command is equal to or greater than the target output current corresponding to the target load (step SA5). As a result, if the output current command is less than the target output current (“NO” in step SA5), the process returns to step SA2 after a predetermined time elapses, the output current command based on the target load is set again, and the newly set output is output. Subsequent steps are performed sequentially based on the current command. The determination in step SA5 is performed at predetermined repetition time intervals, and the setting of the output current command from the target output current corresponding to the target load is also performed at predetermined repetition time intervals. As a result, control commands of various control systems are appropriately executed at predetermined repetition time intervals, and based on this, control of each control system can be performed at approximately the same time, and time until each control amount stabilizes. Can be shortened. Here, the predetermined repetition time interval is the time required to execute the control of each process from step SA2 to step SA5.

By repeating steps SA2 to SA5 in this way, the output current gradually changes toward the target output current, and when the output current reaches the target output current, it is determined as "YES" in step SA5. End control. After the output current reaches the target output current, control is performed so that the output current is maintained at the target output current.

As described above, according to the load increase control unit 4 according to the present embodiment, the output current command setting unit 52 sets the output current command using the current change rate set according to the output current command. Specifically, as shown in FIG. 17, when the output current command is in the current range equal to or less than the current threshold value, the output current command is set using the first current change rate, and the output current command reaches the current threshold value. The output current command is set using the second current change rate until a predetermined period elapses, and after the predetermined period elapses after reaching the current threshold as the change width of the output current command, the third current change rate The output current command is set using. As a result, in the current range where the output current command is below the current threshold, the output current command is set using a relatively large current change rate, so that the time until the output current command reaches the current threshold is relatively short. be able to. Further, in a predetermined period after reaching the current threshold value as the change width of the output current command, by setting the output current command using the second current change rate, the output current command rises very slowly or. Is temporarily stopped.

As a result, it is possible to recover the follow-up delay of the temperature of the power generation chamber during this period. Then, after a predetermined period of time has elapsed from reaching the current threshold value as the change width of the output current command, the output current command is set using the third current change rate set to a value larger than the second current change rate. By doing so, the output current command is gradually increased toward the target output current. As a result, the follow-up delay of the power generation room temperature can be almost eliminated, the temperature converges to the power generation room target temperature shown by the thin broken line, the overshoot of the power generation room temperature is suppressed, and the power generation room temperature becomes the power generation room target after reaching the rated load. It is possible to shorten the time until the temperature stabilizes, and recooling of the power generation chamber due to overshoot is suppressed. Therefore, wasteful energy consumption for raising the temperature of the power generation chamber can be suppressed. In FIG. 17, for comparison, a broken line shows a case where the control for increasing the output current command is continued under the same control without using the second current change rate and the third current change rate until the target temperature of the power generation room is reached. It is shown by. If the output current command is raised in this way and the supply of the fuel gas L2 is continued, the temperature of the power generation chamber will overshoot, and it will take a long time to stabilize at the target power generation chamber temperature.

The load increase control unit 4 according to the present embodiment switches from the first current change rate to the second current change rate when the output current command reaches the current threshold value, but the present invention is not limited to this, for example. When the power generation room temperature, which will be described later, reaches a predetermined temperature threshold value set to be equal to or lower than the second temperature threshold value Tth2 and equal to or lower than the power generation room target temperature Ttag, the first current change rate may be switched to the second current change rate. ..

Next, the temperature rise control unit 5 included in the SOFC control device 60a will be described in detail.
As shown in FIG. 18, the temperature rise control unit 5 includes an air control unit 14 that controls the flow rate of the air (oxidizing agent gas) A1 supplied to the air electrode 13B side and a fuel gas L2 (fuel gas L2) supplied to the air electrode 13B side. It is provided with a fuel gas control unit 15 that controls the flow rate of the flammable gas).
The fuel gas control unit 15 identifies the power generation chamber temperature from the temperature measured by the temperature sensor 92, and starts supplying the fuel gas L2 to the air electrode 13B when the power generation chamber temperature reaches the above-mentioned first temperature threshold Tth1. To do.

Specifically, the fuel gas control unit 15 includes a power generation room temperature specifying unit 16, a second fuel gas flow rate setting unit 17, and a second fuel gas flow rate control unit 18.
The power generation room temperature specifying unit 16 specifies the maximum temperature among the plurality of temperature measurement values measured by the temperature sensor 92 provided in the SOFC cartridge 203 as the power generation room temperature. In the present embodiment, since the SOFC 13 has a temperature distribution, the maximum value among the plurality of measured temperatures measured by the temperature sensor 92 in order to prevent a part of the temperature from exceeding the upper limit temperature. Is specified as the power generation room temperature, but is not limited to this, and for example, the power generation room temperature may be specified from a plurality of temperature measurement values by using an average value of a plurality of temperature measurement values or other statistical methods. Good.

As shown in FIG. 19, the second fuel gas flow rate setting unit 17 is, for example, the temperature of the power generation chamber and the flow rate of the fuel gas L2 added to the air A1 from the air electrode fuel supply line 80 for catalyst combustion at the air electrode 13B. Has the second fuel gas information associated with, and acquires the flow rate of the fuel gas L2 corresponding to the power generation room temperature specified by the power generation room temperature specifying unit 16 from the second fuel gas information, and obtains the acquired fuel. The flow rate of the gas L2 is set as the second fuel gas flow rate command.

Here, as shown in FIG. 19, the second fuel gas information has a characteristic that the second fuel gas flow rate increases until the power generation chamber temperature reaches the second temperature threshold Tth2, and the power generation chamber temperature is the second temperature. It is said that the second fuel gas flow rate decreases after the threshold value Tth2 is reached. After the power generation chamber temperature reaches the second temperature threshold Tth2, the load rise mode is entered, the fuel gas L2 for the power generation reaction is supplied to the fuel electrode 13A, and the power generation chamber temperature rises due to the heat generated by the self-power generation. Because it does. Here, the second fuel gas information in FIG. 19 is set to an appropriate value based on the result of a simulation or an actual machine test.

Further, the second fuel gas flow rate setting unit 17 stops the supply of the fuel gas L2 to the air electrode 13B when the power generation chamber temperature reaches the supply stop temperature Tstop. Here, the supply stop temperature Tstop is set to be larger than the second temperature threshold value Tth2 and equal to or lower than the power generation room target temperature Ttag. In this way, by stopping the supply of the fuel gas L2 to the air electrode 13B before the power generation chamber temperature reaches the power generation chamber target temperature Ttag, it is possible to suppress the overshoot of the power generation chamber temperature. On the other hand, FIG. 19 shows a case where the fuel gas L2 is continuously supplied under the same control according to the temperature of the power generation chamber even after reaching Tstop, with a broken line. If the fuel gas L2 is continuously supplied in this way, the temperature of the power generation chamber will overshoot as shown in FIG. 21 described later, and it will take a long time to stabilize at the target temperature of the power generation chamber.

Here, the supply stop temperature Tstop is set according to, for example, at least one of the first current change rate, the change width of the output current command, and the output current command used by the output current command setting unit 52 described above. .. For example, FIG. 20 shows a flowchart showing an example of a procedure for setting the supply stop temperature. FIG. 20 illustrates a case where the supply stop temperature is set based on the first current change rate, the change width of the output current command, and the output current command.
As shown in FIG. 20, when the output current command corresponding to the target load is equal to or less than the first threshold value (for example, the first threshold value is set to a value in the current range of 25% or more and 40% or less of the rated current). (“NO” in step SB1), the heat generated by the power generation of the SOFC is small, and the risk of overshooting the power generation room temperature is small. Therefore, the supply stop temperature Tstop is 96% of the first temperature (for example, the power generation room target temperature Ttag). ) Is set (step SB2). On the other hand, when the output current command corresponding to the target load is larger than the first threshold value (“YES” in step SB1), then the current increase width is the second threshold value (for example, the second threshold value is the rated current). It is determined whether or not it is larger than (set to a value in the current range of 50% or more and 65% or less) (step SB3). Here, the current increase width is the difference between the current output current value and the output current command corresponding to the target load. For example, when the current output current value is 0A, the output current command and the current increase width are used. Will take the same value as.

In step SB3, when the current increase width is equal to or less than the second threshold value (“NO” in step SB3), the output current command is further set to the third threshold value (for example, the third threshold value is 50% or more and 65% of the rated current). It is determined whether or not it is larger than (set to the value of the following current range) (step SB4). As a result, when the output current command is equal to or less than the third threshold value (“NO” in step SB4), the heat generated by the SOFC power generation is small and the power generation chamber temperature is unlikely to overshoot, so that the supply stop temperature Tstop is set. It is set to the first temperature (step SB2). On the other hand, in step SB4, when the output current command is larger than the third threshold value (“YES” in step SB4), the supply stop temperature Tstop is the second temperature lower than the first temperature (for example, the target temperature of the power generation room). 95%) (step SB5).

Further, in step SB3, when the current increase width is larger than the second threshold value (“YES” in step SB3), the first current change rate is the fourth threshold value (for example, the fourth threshold value is 2% of the rated current / It is determined whether or not it is larger than (set to min) (step SB6). As a result, when the first current change rate is equal to or less than the fourth threshold value (“NO” in step SB6), the process proceeds to step SB4 described above. On the other hand, in step SB6, when the first current change rate is larger than the fourth threshold value (“YES” in step SB6), the supply stop temperature Tstop is the third temperature lower than the second temperature (for example, the power generation room target). It is set to (93% of temperature) (step SB7).

In this way, the larger the output current command, the current increase width, and the current change rate, and the easier it is to overshoot, the lower the supply stop temperature Tstop is set. As a result, the supply of the fuel gas L2 to the air electrode 13B can be stopped before the temperature of the power generation chamber reaches the target temperature of the power generation chamber, and overshoot of the temperature of the power generation chamber can be suppressed.
Regarding the setting of the supply stop temperature Tstop described above, for example, at the start of SOFC 13, in other words, before the first temperature rise mode described above is started, the process shown in FIG. 20 is executed once. The supply stop temperature Tstop may be set. Further, since the output current command is set at a predetermined repetition time interval, the Tstop may be reset according to the reset output current command, the current increase width, and the current change rate.

As described above, according to the temperature rise control unit 5 according to the present embodiment, as shown in FIG. 21, the flow rate of the fuel gas L2 can be controlled by suppressing the overshoot of the power generation chamber temperature. Further, for comparison, the broken line shows the case where the fuel gas L2 is continuously supplied under the same control until the target temperature of the power generation chamber is reached even after Tstop. If the fuel gas L2 is continuously supplied in this way, the temperature of the power generation chamber will overshoot, and it will take a long time to stabilize at the target temperature of the power generation chamber. Further, as shown in FIGS. 19 and 21, when the power generation chamber temperature reaches the preset first temperature threshold Tth1, the supply of the fuel gas L2 to the air electrode 13B is started, and the power generation chamber temperature becomes the first. When the supply stop temperature Tstop set to be larger than the temperature threshold Tth1 and equal to or lower than the target temperature Ttag of the power generation room is reached, the supply of the fuel gas L2 to the air electrode 13B is stopped. After the supply of the fuel gas L2 is stopped, the temperature of the power generation room rises only by the heat generated by the power generation. As a result, after the power generation chamber is quickly raised to Tth2 or Tstop, the temperature of the power generation chamber can be gradually raised to the target temperature Ttag of the power generation chamber, overshoot can be suppressed, and the power generation chamber due to overshoot can be suppressed. Recooling is suppressed. Therefore, wasteful energy consumption for raising the temperature of the power generation chamber can be suppressed.
Further, since the supply stop temperature Tstop is set according to the first current change rate used when setting the output current command, the output current command, and the change width thereof, it is appropriate according to the state of load increase. It is possible to set the supply stop temperature Tstop to the temperature.

As described above, according to the fuel cell control device, control method, and power generation system, it is possible to shorten the time to reach the target while avoiding overshoot of the controlled amount when the load increases.
In the present embodiment, the case where the load increase control unit 4 switches the current change rate and the temperature increase control unit 5 stops the supply of the fuel gas L2 at the supply stop temperature Tstop has been described. One of the controls may be performed. For example, when the load increase control unit 4 switches the current change rate, the temperature increase control unit 5 sets the power generation room temperature to the power generation room target temperature without stopping the supply of the fuel gas L2 at the supply stop temperature Tstop. The fuel gas L2 may be continuously supplied based on the second fuel gas information shown in FIG. 19 until the temperature reaches Ttag.

Further, when the supply stop temperature Tstop of the fuel gas L2 is stopped by the temperature information control unit 5, for example, the load increase control unit 4 does not switch the current change rate, and the output current command outputs the target output. The output current command may be set using only the first current change rate until the current is reached.

4: Load increase control unit 5: Temperature increase control unit 10: Power generation system 11: MGT (micro gas turbine)
12: Generator 13A: Fuel pole 13B: Air pole 14: Air control unit 15: Fuel gas control unit 16: Power generation room temperature specifying unit 17: Second fuel gas flow rate setting unit 18: Second fuel gas flow rate control unit 51: Target load setting unit 52: Output current command setting unit 53: Control command setting unit 53a: First fuel gas flow rate setting unit 53b: Inlet air temperature setting unit 53c: MGT output setting unit 53d: Differential pressure setting unit 53e: Recirculation flow rate Setting unit 53f: Pure water flow rate setting unit 54: Control unit 54a: First fuel gas flow rate control unit 54b: Inlet air temperature control unit 54c: MGT output control unit 54d: Differential pressure control unit 54e: Recirculation flow rate control unit 54f: Pure water flow control unit 60: Control device 60a: SOFC control device 60b: MGT control device 90: Differential pressure sensor 92: Temperature sensor 94: Outside air temperature sensor 105: Fuel cell cell 111: Solid oxide 201: SOFC module 203: SOFC cartridge 215: Power generation room

Claims (14)

A fuel cell control device including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged.
The target load setting unit that sets the target load and
An output current command setting unit that sets an output current command of the fuel cell from the target load using a predetermined current change rate, and an output current command setting unit.
A control command setting unit that sets control commands to a plurality of control systems for changing the load of the fuel cell using the output current command, and a control command setting unit.
When the power generation chamber temperature reaches a preset first temperature threshold, the supply of flammable gas to the air electrode is started, and the power generation chamber temperature is larger than the first temperature threshold and equal to or lower than the power generation chamber target temperature. It is provided with a flammable gas flow rate control unit that stops the supply of the flammable gas to the air electrode when the supply stop temperature set in is reached.
The fuel cell control device in which the supply stop temperature is set according to at least one of the predetermined current change rate, the output current command corresponding to the target load, and the change width of the output current command. A fuel cell control device including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged.
The target load setting unit that sets the target load and
An output current command setting unit that sets an output current command of the fuel cell from the target load using a predetermined first current change rate, and an output current command setting unit.
A control command setting unit that sets control commands to a plurality of control systems for changing the load of the fuel cell by using the output current command set by the output current command setting unit.
With
Said output current command setting unit, when the output current command reaches the set current threshold below the target output current corresponding to the target load, or temperature of the generating chamber temperature is set below the generating chamber target temperature When the temperature threshold is reached, the output current command is set using the second current change rate set to a value smaller than the first current change rate.
The fuel cell control device in which the current threshold value or the temperature threshold value is set according to the first current change rate. The output current command setting unit is the second when a predetermined time has elapsed since the output current command reached the current threshold value, or when a predetermined time has elapsed since the temperature of the power generation chamber reached the temperature threshold value. The fuel cell control device according to claim 2, wherein the output current command is set using a third current change rate set larger than the current change rate. The fuel cell control device according to claim 2 or 3, wherein the second current change rate is set to zero. The fuel cell control device according to any one of claims 2 to 4, wherein the target load setting unit sets a target load of the fuel cell from the outside air temperature around the fuel cell. When the power generation chamber temperature reaches a preset first temperature threshold, the supply of flammable gas to the air electrode is started, and the power generation chamber temperature is larger than the first temperature threshold and the power generation chamber target temperature. A flammable gas flow control unit that stops the supply of the flammable gas to the air electrode when the supply stop temperature set below is reached is provided.
Claims 2 to 5 are set in accordance with at least one of the predetermined current change rate, the output current command corresponding to the target load, and the change width of the output current command. The fuel cell control device according to any one of. The fuel cell control device according to claim 1 or 6, wherein the supply stop temperature is set to a lower value as the rate of change, the width of change of the output current command, or the output current command is larger. .. The fuel cell control device according to claim 1, wherein the target load setting unit sets a target load of the fuel cell from the outside air temperature around the fuel cell. The plurality of control systems include fuel gas supply flow rate to the fuel electrode, fuel cell air electrode inlet temperature, micro gas turbine output, differential pressure between the fuel electrode and the air electrode, recirculation blower rotation speed, and pure water flow rate. The fuel cell control device according to any one of claims 1 to 8, which comprises two or more of them. The fuel cell control device according to any one of claims 1 to 9, wherein the fuel cell is a solid oxide fuel cell. A fuel cell including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged.
A power generation system including the fuel cell control device according to any one of claims 1 to 10. A plurality of temperature measuring units provided in the central region of the power generation chamber are provided.
The power generation system according to claim 11, wherein the maximum temperature among the plurality of measured temperatures measured by the temperature measuring unit is used as the power generation room temperature. A method for controlling a fuel cell having a power generation chamber in which a plurality of power generation cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged.
A temperature measurement process for measuring the temperature of a predetermined measurement point provided in the power generation chamber, and
The target load setting process for setting the target load and
A current command setting step of setting an output current command of the fuel cell from the target load using a predetermined rate of change, and a current command setting process.
A control command setting step of setting control commands to a plurality of control systems for changing the load of the fuel cell by using the output current command, and
A supply start step of supplying a flammable gas to the air electrode when the power generation chamber temperature specified from the measured temperature measured in the temperature measurement step reaches a preset first temperature threshold value, and
It is provided with a supply stop step of stopping the supply of the combustible gas to the air electrode when the power generation chamber temperature reaches the supply stop temperature set to be larger than the first temperature threshold value and equal to or lower than the power generation room target temperature. ,
A fuel cell control method in which the supply stop temperature is set according to at least one of the predetermined current change rate, the output current command corresponding to the target load, and the change width of the output current command. A method for controlling a fuel cell having a power generation chamber in which a plurality of power generation cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged.
A temperature measurement process for measuring the temperature of a predetermined measurement point provided in the power generation chamber, and
The target load setting process for setting the target load and
An output current command setting step of setting an output current command of the fuel cell from the target load using a predetermined first current change rate, and an output current command setting step.
A control command setting step of setting control commands to a plurality of control systems for changing the load of the fuel cell by using the output current command, and
With
Said output current command setting step, when the output current command reaches the set current threshold below the target output current corresponding to the target load, or temperature of the generating chamber temperature is set below the generating chamber target temperature When the temperature threshold is reached, the output current command is set using the second current change rate set to a value smaller than the first current change rate.
The fuel cell control method in which the current threshold value or the temperature threshold value is set according to the first current change rate.

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