JP6843531B2 - 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 (oxidizing agent 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 using gas produced from a carbonaceous raw material such as gasified gas by a gasification facility as fuel. 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 to be burned, and the combustion generated in the combustor is performed. By adiabatic expansion of the gas to rotationally drive the turbine of the MGT and rotationally drive the generator, it is possible to generate electricity with high power generation efficiency (see Patent Document 1).

Further, Patent Document 2 discloses that the flow rate of fuel gas and the flow rate of oxidant gas required for power generation current are determined by feedforward control with respect to a change in load.
Further, Patent Document 3 discloses a power generation system having a recirculation line for recirculating the high-temperature exhaust fuel gas discharged from the power generation chamber of the SOFC to the fuel supply path.

Japanese Unexamined Patent Publication No. 2015-11525 Japanese Unexamined Patent Publication No. 2003-223912 Japanese Patent No. 5601945

The recirculation line is provided with equipment such as a control valve and a blower for controlling the flow rate of the exhaust fuel gas flowing through the recirculation line. Therefore, it is necessary to limit the exhaust fuel gas flowing through the recirculation line to the heat resistant temperature or lower of these devices.
As a method of controlling the temperature of the exhaust fuel gas flowing through the recirculation line, it is conceivable to reduce the load. However, reducing the load for adjusting the temperature of the exhaust fuel gas is not preferable because it goes against the original purpose of the power generation facility of generating more power. Further, it is conceivable to provide another device such as a heat exchanger to adjust the temperature, but this method is not preferable in terms of the size of the device and the cost.

The present invention has been made in view of such circumstances, and suppresses the temperature of the exhaust fuel gas flowing through the recirculation line of the fuel cell to a temperature upper limit value or less determined from the heat resistant temperature of the device by a simple method. It is an object of the present invention to provide a fuel cell control device and a control method as well as a power generation system which can be used.

The present invention includes 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 is discharged from an oxidizing agent gas before being supplied to the air electrode and the fuel electrode. a exhaust and fuel gas control apparatus for a fuel cell that will be heat exchange after, by circulating the exhaust fuel gas after being said heat exchanger, again flows through the recirculation line to be supplied to the fuel electrode Provided is a fuel cell control device including an inlet oxidant temperature control unit that controls the temperature of the oxidant gas supplied to the air electrode so that the temperature of the exhaust fuel gas is within a predetermined range.

According to the present invention, the temperature of the oxidant gas supplied to the air electrode is controlled so that the temperature of the exhaust fuel gas flowing through the recirculation line is within a predetermined range. As a result, the temperature of the exhaust fuel gas can be suppressed to be equal to or lower than the heat resistant temperature of the recirculation blower or control valve provided in the recirculation line. Here, the predetermined range of the exhaust fuel gas is, for example, 600 ° C. or lower, more preferably 550 ° C. or lower.

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 the exhaust fuel gas discharged from the fuel electrode side. An inlet oxidant that controls the temperature of the oxidant gas supplied to the air electrode so that the temperature of the exhaust fuel gas flowing through the recirculation line that circulates and supplies the fuel electrode again is within a predetermined range. The temperature control unit, the first information associated with the output current command and the inlet oxidant temperature, the second information associated with the power generation chamber temperature and the inlet oxidant temperature, the exhaust fuel outlet temperature and the inlet oxidant temperature From the associated third information, the corresponding inlet oxidant temperature is acquired, the inlet oxidant temperature having the smallest value is selected from the acquired inlet oxidizer temperature, and the inlet oxidant temperature is set as the inlet oxidizer temperature command. and a temperature setting unit, the inlet oxidant temperature control unit, a control device for fuel cell that controls the inlet oxidant temperature based on the inlet oxidant temperature command set by said inlet oxidant temperature setting unit Provide .

In this way, the inlet oxidizer temperature command is acquired from the output current command, the power generation chamber temperature, and the exhaust fuel outlet temperature, and the inlet oxidizer temperature command with the smallest command value is set from the acquired inlet oxidizer temperature commands. To do. As a result, the temperature of the oxidant gas that exchanges heat with the flammable gas supplied to the fuel electrode can be set to the lowest possible temperature in the fuel cell. As a result, the exhaust fuel gas discharged from the fuel cell to the recirculation line can be effectively cooled, and the temperature of the exhaust fuel gas can be easily adjusted.

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

The present invention includes 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 is discharged from an oxidizing agent gas before being supplied to the air electrode and the fuel electrode. the fuel according the exhaust fuel gas and the fuel cell is Ru by heat exchange, by circulating the exhaust fuel gas after being the heat exchanger, again with the recirculation line to be supplied to the fuel electrode, the one after the Provided is a power generation system including a battery control device.

The present invention includes 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 is discharged from the oxidant gas before being supplied to the air pole and the fuel pole. a control method of a fuel cell and exhaust fuel gas is Ru is heat-exchanged later by circulating exhaust fuel gas after being the heat exchanger, the exhaust fuel again and supplying to the fuel electrode, is circulated A step of measuring the temperature of the gas, a step of measuring the temperature of the oxidizing agent gas supplied to the air electrode side, and an oxidation supplied to the air electrode so that the temperature of the exhaust fuel gas is within a predetermined range. Provided is a method for controlling a fuel cell, which comprises a step of controlling the temperature of an agent gas.
The present invention is a method for controlling 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 the exhaust fuel gas discharged from the fuel electrode side. An inlet oxidant that controls the temperature of the oxidant gas supplied to the air electrode so that the temperature of the exhaust fuel gas flowing through the recirculation line that circulates and supplies the fuel electrode again is within a predetermined range. The temperature control process, the first information associated with the output current command and the inlet oxidant temperature, the second information associated with the power generation chamber temperature and the inlet oxidant temperature, the exhaust fuel outlet temperature and the inlet oxidant temperature From the associated third information, the corresponding inlet oxidant temperature is acquired, the inlet oxidant temperature having the smallest value is selected from the acquired inlet oxidizer temperature, and the inlet oxidant temperature is set as the inlet oxidizer temperature command. The inlet oxidant temperature control step includes a temperature setting step, and provides a fuel cell control method for controlling the inlet oxidant temperature based on the inlet oxidant temperature command set in the inlet oxidant temperature setting step. To do.

According to the present invention, there is an effect that the temperature of the exhaust fuel gas flowing through the recirculation line of the fuel cell can be controlled to an appropriate temperature by a simple method.

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 of the load increase mode about the SOFC control apparatus which concerns on one Embodiment of this invention. It is a figure which showed an example of the target load information. It is a figure which showed an example of fuel gas flow rate information. It is a figure which showed an example of the 1st inlet air temperature information. It is a figure which showed an example of the 2nd inlet air temperature information. It is a figure which showed an example of the 3rd 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 fuel air 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 in the load increase mode 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 electricity. 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 the 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 of 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 that supplies 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.

The SOFC 13 is connected to an exhaust air discharge line 34 that discharges the exhaust air A2 used in the air electrode 13B. An exhaust air supply line 36 for supplying the 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 control of 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. By controlling the discharge flow rate of the pump 48 by the control device 60, the amount of pure water supplied to the fuel electrode 13A is adjusted.

[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. The lead film 115 is electrically connected to the fuel cell 105 at the other end of the fuel cell 105, and is electrically connected to the fuel electrode 13A of the fuel cell 105 (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 fuel cell.

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 13A 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 the 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. Gas produced from carbonaceous raw materials such as methanol and coal gas by a gasification facility. In the present embodiment, the fuel gas L2 is, for example, a city gas, and a fuel gas containing methane as a main component is used.

The solid electrolyte 111 is mainly composed of YSZ having airtightness that makes it difficult for 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 thickness of the solid electrolyte membrane 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 membrane 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 portion 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 a flat plate cell stack may be used, for example. 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 resistance and corrosion resistance to an oxidizing agent 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 led 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, the upper pipe plate 225a, and the upper heat insulating body 227a of the SOFC cartridge 203, and is illustrated by the air discharge holes 233b provided on the side surface of the upper casing 229a. Not 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 exchanges heat 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 temperature sensor 92 is 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 are provided. The temperature sensor 92 is arranged at least in the central region of the cell stack 101 in the longitudinal direction in the power generation chamber 215. The central region in the present embodiment is a region including the position where the temperature is 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. You can go on. 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 the 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. You may.

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 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 the functions provided by the control device 60 according to the present embodiment in an expanded manner. 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 power generation chamber temperature reaches the first temperature threshold value Tth1 by the first temperature rising mode, the first temperature rising mode is switched to the second temperature rising mode. Here, the first temperature threshold value is a temperature at which the air electrode 13B functions as a catalyst for a 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 chamber 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, for example, the target. The supply of the fuel gas L2 to the air electrode 13A 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 to generate electricity, 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. When 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 temperature of the power generation room reaches the target temperature Ttag of the power generation room 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 heat generated by 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, the load increase mode, which is a feature 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 load increase mode.
As shown in FIG. 6, the SOFC control device 60a 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. 7 is a diagram showing an example of target load information. In FIG. 7, 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 64 or the like is fully opened. When the air flow rate A1 is set to the maximum, the value of the maximum load (maximum 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 64 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. Therefore, the air A1 supplied to the power generation chamber 215 functions as a coolant. Therefore, the larger the amount of air, the higher the SOFC13. The maximum load that can be output can be increased. 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. 7, 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 deviates from the purpose of increasing the output of SOFC 13 as much as possible, which is not preferable. Further, if it is less than 0.1%, it is not preferable because it falls within the control error range of a flow 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 changes instantaneously, the response of each control amount cannot be followed, the fuel gas temporarily becomes excessive or deficient, and the operation of the power generation system 10 becomes 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. The predetermined repetition time interval is the time required to sequentially execute a series of control processing steps and perform a step of determining whether or not the output current command has reached the target current. For example, if the target output current is set to 90% of the rated current and the current change rate is set to 5% / min of the rated current, the output current command after 10 minutes becomes 50% of the rated current, which takes about 18 minutes. The load will be increased to the target output current.
The predetermined current change rate may be changed according to the difference between the output current value and the target output current. For example, when the difference is large, the output current command may be set with a relatively large current change rate, and the current change rate may be set to decrease as the difference becomes smaller. By changing the current change rate in this way, it is possible to shorten the time required to reach the target output current and suppress overshoot of the temperature of the power generation chamber.

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 or the like set by the output current command setting unit 52. Here, the control command does not issue the next control command after the output current, which is the control amount, and the change in the temperature of the power generation room are stabilized by issuing individual control commands, but the control commands related to a plurality of control systems are issued almost at the same time. Try to put it out. For example, the control command setting unit 53 sets the fuel gas flow rate setting unit 53a for setting the flow command of the fuel gas L2 supplied to the fuel electrode 13A, and the inlet air temperature for setting the inlet air temperature command for the air A1 supplied to the air electrode 13B. The setting unit 53b, the MGT output setting unit 53c for setting the MGT output command, the fuel air differential pressure setting unit 53d for setting the differential pressure command between the fuel electrode 13A and the air electrode 13B, and the rotation speed command for the recirculation blower 50 are set. It includes a recirculation 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. 8, for example, the fuel gas flow rate setting unit 53a has 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 fuel gas flow rate information is changed to the output current command. The flow rate of the corresponding fuel gas L2 is acquired, and the acquired flow rate of the fuel gas L2 is set as the fuel gas flow rate command.
The inlet air temperature setting unit (inlet oxidant temperature setting unit) 53b is, for example, as shown in FIG. 9, the first 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. (First information) is provided. Further, the inlet air temperature setting unit 53b uses the second inlet air temperature information (second information) in which the power generation chamber temperature and the inlet air temperature are associated with each other as shown in FIG. 10, and the exhaust fuel outlet temperature and the inlet air shown in FIG. The third inlet air temperature information (third information) associated with the temperature command is provided. The inlet air temperature setting unit 53b obtains the inlet air temperature corresponding to the output current command from the first inlet air temperature information, the inlet air temperature corresponding to the power generation room temperature from the second inlet air temperature information, and the third inlet air temperature information. Obtain the inlet air temperature corresponding to the exhaust fuel outlet temperature from. Then, the inlet air temperature having the smallest value among these acquired inlet air temperatures is set as the inlet air temperature command. This makes it possible to prevent the SOFC 13 and the power generation system 10 from overheating.

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 in by 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.

As shown in FIG. 13, for example, the fuel air differential pressure setting unit 53d provides differential pressure information in which the output current command and the fuel air differential pressure, which is the differential pressure between the fuel electrode 13A and the air electrode 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.
As shown in FIG. 14, for example, the recirculation flow rate setting unit 53e has rotation speed information associated with the output current command and the blower rotation speed, and the exhaust fuel gas of the recirculation line 49 is determined by the blower rotation speed. The flow rate for recirculating a part of L3 is controlled. The rotation speed corresponding to the output current command is acquired from the rotation speed information, and the acquired 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. 7, 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 fuel gas flow rate control unit 54a, an inlet air temperature control unit (inlet oxidizer control unit) 54b, an MGT output control unit 54c, a fuel air differential pressure control unit 54d, a recirculation flow rate control unit 54e, and a pure water flow rate. The control unit 54f is provided.
The fuel gas flow rate control unit 54a adjusts the amount of fuel gas supplied to the fuel electrode 13A by controlling the valve opening degree of the control valve 42 based on the fuel gas flow rate command from the fuel gas flow rate setting unit 53a.
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 fuel air differential pressure control unit 54d adjusts the valve opening degree of the control valve 47 based on the fuel air differential pressure command from the fuel air differential pressure setting unit 53d, so that the fuel electrode 13A side is predetermined from the air electrode 13B side. The fuel air differential pressure in the power generation chamber 215 is controlled so as to increase in the range of (for example, 0.1 to 1 kPa).
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 fuel gas flow rate control unit 54a, the inlet temperature control unit 54b, the MGT output control unit 54c, the fuel air differential pressure control unit 54d, the recirculation flow rate control unit 54e, and the pure water flow rate control unit 54f. Is issued a control command 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 command. Since known techniques may be appropriately applied to these controls, detailed description thereof will be omitted. For example, the various manipulated variables in the control commands of the 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. 8 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 SOFC control device 60a according to the present embodiment 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 the output current command from the target load, in other words, the target output current, using a predetermined current change rate (step SA2). For example, assuming that the current change rate is 4 A / min, the command value of the output current command in the first minute is set to 4 A.

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 load (= target output current) (step SA5). As a result, if the output current command is less than the target load (“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 current is set. Subsequent steps are performed sequentially based on the 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 the 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 command gradually changes toward the target output current, and when the output current command reaches the target output current, it is determined as "YES" in step SA5. , End this process. After the output current command reaches the target output current, for example, control is performed to maintain the output current of the SOFC 13 at the target output current.

As described above, according to the fuel cell control device and control method and the power generation system according to the present embodiment, the target load (= target output current) of the SOFC 13 is used from the outside air temperature using the target load information shown in FIG. Is set. The target load information is the maximum load (maximum current) that the SOFC 13 can output when the valve opening of the control valve 65 is fully closed, in other words, when the air flow rate supplied to the air electrode 13B is set to the maximum. The value of is set in association with the outside air temperature. Therefore, by setting the target load from the outside air temperature using such target load information, it is possible to set the target load close to the output upper limit value that can be output by the SOFC 13. This makes it possible to improve the output of the fuel cell to near the capacity limit.

Further, the inlet air temperature setting unit 53b obtains information from a plurality of parameters associated with the inlet air temperature to the air electrode 13B of the SOFC 13. In the present embodiment, for example, the inlet air temperature is acquired based on the power generation chamber temperature, the output current command, and the outlet exhaust fuel temperature, and the inlet air temperature having the smallest value among the acquired inlet air temperatures is designated as the inlet air temperature command. Set as. In this way, by setting the inlet air temperature command at which the inlet air temperature is the lowest, it is possible to suppress overheating such as the temperature of the power generation chamber 215 and the outlet exhaust fuel temperature. As a result, the temperature rise of the exhaust fuel gas L3 can be easily suppressed without the need for additional equipment, and the heat resistance of the recirculation blower 50 or the like that requires the temperature upper limit of the exhaust fuel gas L3 to be controlled. It is possible to limit the temperature below the temperature.

The present invention is not limited to the above-described embodiments, and various modifications can be made within a range that does not deviate from the gist of the invention, for example, by partially or wholly combining the above-mentioned embodiments. Is.

10: Power generation system 11: MGT (micro gas turbine)
12: Generator 13A: Fuel electrode 13B: Air electrode 49: Fuel gas recirculation line 50: Recirculation blower 51: Target load setting unit 52: Output current command setting unit 53: Control command setting unit 53a: Fuel gas flow rate setting unit 53b: Inlet air temperature setting unit 53c: MGT output setting unit 53d: Fuel air differential pressure setting unit 53e: Recirculation flow rate setting unit 53f: Pure water flow rate setting unit 54: Control unit 54a: Fuel gas flow rate control unit 54b: Inlet air Temperature control unit 54c: MGT output control unit 54d: Fuel air differential pressure control unit 54e: Recirculation flow rate control unit 54f: Pure water flow rate control unit 60: Control device 60a: SOFC control device 92: Temperature sensor 94: Outside air temperature sensor 105 : Fuel cell 111: Solid oxide 201: SOFC module 203: SOFC cartridge 215: Power generation room

Claims (7)

It is provided with 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 an oxidant gas before being supplied to the air electrode and exhaust after being discharged from the fuel electrode. and a fuel gas a control apparatus for a fuel cell that will be heat-exchanged,
By circulating exhaust fuel gas after being the heat exchanger, it is such that the temperature of the exhaust fuel gas flowing through the recirculation line to be supplied to the fuel electrode becomes within a predetermined range again, supplied to the air electrode A fuel cell control device including an inlet oxidant temperature control unit that controls the temperature of the oxidant gas. 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 exhaust fuel gas discharged from the fuel electrode side is circulated and supplied to the air electrode so that the temperature of the exhaust fuel gas flowing through the recirculation line supplied to the fuel electrode again is within a predetermined range. An inlet oxidant temperature control unit that controls the temperature of the oxidant gas,
The first information associated with the output current command and the inlet oxidant temperature, the second information associated with the power generation chamber temperature and the inlet oxidant temperature, and the third information associated with the exhaust fuel outlet temperature and the inlet oxidizer temperature. from the information, obtains the corresponding inlet oxidant temperature, the obtained inlet oxidant select a smaller inlet oxidant temperature most value among the temperature is set as the inlet oxidant temperature command inlet oxidant temperature setting unit Prepare,
The inlet oxidant temperature control unit, the control device of the fuel cell that controls the inlet oxidant temperature based on the inlet oxidant temperature command set by said inlet oxidant temperature setting unit. The fuel cell control device according to claim 1 or 2, wherein the predetermined range of the exhaust fuel gas is 600 ° C. or lower. The fuel cell control device according to any one of claims 1 to 3, wherein the fuel cell is a solid oxide fuel cell. It is provided with 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 an oxidant gas before being supplied to the air electrode and exhaust after being discharged from the fuel electrode. a fuel cell and a fuel gas Ru is heat-exchanged,
A recirculation line that circulates the exhaust fuel gas after heat exchange and supplies it to the fuel electrode again.
A power generation system including the fuel cell control device according to any one of claims 1 to 4. It is provided with 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, and an oxidant gas before being supplied to the air electrode and exhaust fuel after being discharged from the fuel electrode. a control method of a fuel cell and a gas Ru is heat-exchanged,
The process of circulating the exhaust fuel gas after the heat exchange and supplying it to the fuel electrode again.
The process of measuring the temperature of the exhaust fuel gas to be circulated, and
The process of measuring the temperature of the oxidant gas supplied to the air electrode side and
A method for controlling a fuel cell, which comprises a step of controlling the temperature of the oxidant gas supplied to the air electrode so that the temperature of the exhaust fuel gas is within a predetermined range. A method for controlling a fuel cell having 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 exhaust fuel gas discharged from the fuel electrode side is circulated and supplied to the air electrode so that the temperature of the exhaust fuel gas flowing through the recirculation line supplied to the fuel electrode again is within a predetermined range. An inlet oxidant temperature control process that controls the temperature of the oxidant gas, and
The first information associated with the output current command and the inlet oxidant temperature, the second information associated with the power generation chamber temperature and the inlet oxidant temperature, and the third information associated with the exhaust fuel outlet temperature and the inlet oxidizer temperature. From the information, the corresponding inlet oxidant temperature is acquired, the inlet oxidant temperature having the smallest value is selected from the acquired inlet oxidant temperatures, and the inlet oxidant temperature setting step is set as the inlet oxidizer temperature command. Have and
The inlet oxidant temperature control step is a fuel cell control method for controlling the inlet oxidant temperature based on the inlet oxidant temperature command set in the inlet oxidant temperature setting step.

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