JP7293466B1 - FUEL CELL SYSTEM AND METHOD OF OPERATION OF FUEL CELL SYSTEM - Google Patents

Abstract

An object of the present invention is to shorten the start-up time required from the start of supply of fuel gas to a fuel electrode until the generation chamber reaches a predetermined heated state. A fuel cell (313), a turbocharger (411), an oxidizing gas supply line (331) for supplying an oxidizing gas compressed by a compressor (421) to an air electrode (113), and a fuel gas for supplying a fuel gas (L1) to a fuel electrode (109). line 341, starting heater 458 for heating oxidizing gas, blow valve 445 arranged in oxidizing gas blow line 444 connected to oxidizing gas supply line 331, and fuel gas L1 to fuel electrode 109. The blow valve 445 is opened when the supply of the fuel cell 313 is started, and when the power generation chamber of the fuel cell 313 reaches a predetermined heating state by the oxidizing gas A2 heated by the heater 458 for start-up, the blow valve 445 a controller 20 that controls the control valve 342 and the blow valve 445 to switch to a closed state. [Selection drawing] Fig. 4

Description

The present disclosure relates to fuel cell systems and methods of operating fuel cell systems.

A fuel cell that generates power by chemically reacting a fuel gas and an oxidizing gas has characteristics such as excellent power generation efficiency and environmental friendliness. Among these, solid oxide fuel cells (Solid Oxide Fuel Cells: hereinafter referred to as "SOFC") use ceramics such as zirconia ceramics as electrolytes, and hydrogen, city gas, natural gas, petroleum, methanol, and carbon-containing raw materials is supplied as a fuel gas, such as a gasified gas produced by a gasification facility, and reacted in a high-temperature atmosphere of about 700°C to 1000°C to generate power (see, for example, Patent Document 1).

Patent Literature 1 discloses an SOFC system in which an SOFC and a turbocharger are combined. In Patent Document 1, exhaust fuel gas discharged from an SOFC is combusted in a combustor, and the combustion gas is supplied to a turbine to rotationally drive the turbine. A compressor coupled to the turbine compresses the oxidizing gas and supplies it to the cathode.

Further, in Patent Document 1, in order to make the generation chamber a high-temperature atmosphere when starting the SOFC, the oxidizing gas supplied to the air electrode is heated by a start-up heater, and the fuel gas is supplied to the air electrode. It is disclosed that the temperature of the power generation chamber is raised by catalytic reaction.

Japanese Patent No. 6922016

However, when the power generation chamber is in a low-temperature atmosphere (for example, 400° C. to 500° C.), the catalytic activity of the fuel cell is low, so the amount of oxidizing gas supplied to the air electrode is supplied to the fuel electrode. It may be excessive with respect to the supply amount of fuel gas. In this case, the combustion in the generator chamber cannot be sufficiently performed, and the start-up time from the low temperature atmosphere to the high temperature atmosphere becomes long.

In order to raise the temperature of the generating chamber, it is possible to increase the amount of fuel gas supplied to the air electrode to promote the catalytic reaction, but there is a limit to the ability of the catalytic reaction in a low-temperature atmosphere. Therefore, even if the amount of fuel gas supplied to the air electrode is increased, there is a possibility that the temperature of the generator chamber cannot be sufficiently raised.

In addition, when the fuel gas supplied to the air electrode is increased and the unreacted exhaust fuel gas discharged from the air electrode increases, the number of rotations per unit time of the turbine driven by the exhaust fuel gas and the compressor The flow rate of the oxidizing gas supplied to the air electrode increases. As a result, the supply amount of the oxidizing gas supplied to the air electrode becomes excessive with respect to the supply amount of the fuel gas supplied to the fuel electrode, further lengthening the start-up time.

The present disclosure has been made in view of such circumstances, and it is possible to shorten the startup time required from the start of fuel gas supply to the fuel electrode until the power generation chamber reaches a predetermined heating state. An object of the present invention is to provide an efficient fuel cell system and a method of operating the fuel cell system.

In order to solve the above problems, the present disclosure employs the following means.
A fuel cell system according to the present disclosure is driven by a fuel cell having an air electrode and a fuel electrode, a turbine to which exhaust fuel gas and exhaust oxidizing gas discharged from the fuel cell are supplied as combustion gas, and the turbine. a turbocharger having a compressor; an oxidizing gas supply line for supplying the oxidizing gas compressed by the compressor to the air electrode; a fuel gas line for supplying fuel gas to the fuel electrode; a fuel gas control valve disposed; a heating unit for heating the oxidizing gas flowing through the oxidizing gas supply line; and a blower connected to the oxidizing gas supply line and discharging the oxidizing gas to the outside. a blow valve disposed in the blow line; and the blow valve is opened when the fuel gas control valve is switched from a closed state to an open state to start supplying the fuel gas to the fuel electrode. and the fuel gas control valve and the blow valve are switched to a closed state when the generating chamber of the fuel cell reaches a predetermined heated state by the oxidizing gas heated by the heating unit. and a control device for controlling.

A method of operating a fuel cell system according to the present disclosure is a method of operating a fuel cell system, the fuel cell system comprising: a fuel cell having an air electrode and a fuel electrode; exhaust fuel gas discharged from the fuel cell; a turbocharger having a turbine to which exhaust oxidizing gas is supplied as combustion gas and a compressor driven by the turbine; an oxidizing gas supply line for supplying the oxidizing gas compressed by the compressor to the air electrode; a fuel gas line for supplying fuel gas to the fuel electrode; a fuel gas control valve arranged in the fuel gas line; a heating unit for heating the oxidizing gas flowing through the oxidizing gas supply line; a blow line connected to a toxic gas supply line for discharging the oxidizing gas to the outside; and a blow valve disposed in the blow line, the blow valve being opened; is in an open state, switching the fuel gas control valve from a closed state to an open state to start supplying the fuel gas to the fuel electrode; a control step of controlling the blow valve so as to switch the blow valve to a closed state in response to a predetermined heating state due to the supplied oxidizing gas.

According to the present disclosure, there is provided a fuel cell system and a method of operating the fuel cell system capable of shortening the start-up time required from the start of supply of fuel gas to the fuel electrode until the generation chamber reaches a predetermined heated state. can provide.

FIG. 2 is a diagram showing an example of a cell stack according to the first embodiment of the present disclosure; FIG. 1 is a diagram illustrating an example of an SOFC module according to a first embodiment of the present disclosure; FIG. 1 is a diagram illustrating an example of an SOFC cartridge according to a first embodiment of the present disclosure; FIG. 1 is a diagram showing a schematic configuration of a fuel cell system according to a first embodiment of the present disclosure; FIG. It is a figure showing an example of hardware constitutions of a control device concerning a 1st embodiment of this indication. 4 is a flow chart showing a method for starting the fuel cell system according to the first embodiment of the present disclosure; 4 is a graph showing changes in fuel gas supplied to a catalytic combustor; 4 is a graph showing changes in blow valve opening. 4 is a graph showing changes in the flow rate of fuel gas supplied to the fuel electrode; It is a graph which shows the change of the temperature of a power generation room. 4 is a graph showing changes in the number of revolutions of a turbine; 4 is a graph showing changes in the flow rate of oxidizing gas supplied to the power generation chamber; 4 is a graph showing changes in the degree of opening of a heating control valve; 4 is a graph showing changes in the degree of opening of an oxidizing gas control valve; It is a graph which shows the change of the temperature of a power generation room.

[First embodiment]
A first embodiment of a fuel cell system and a method of operating the same according to the present disclosure will be described below with reference to the drawings.

In the following, for convenience of explanation, the positional relationship of each component described using the expressions "upper" and "lower" with respect to the paper surface indicates the vertical upper side and the vertical lower side, respectively. is not precise and contains errors. Further, in this embodiment, the same effect can be obtained in the vertical direction and the horizontal direction. good.

In the following description, a cylindrical (cylindrical) cell stack of a solid oxide fuel cell (SOFC) will be described as an example, but this is not necessarily the case. good too. Although the fuel cell is formed on the substrate, the electrode (the fuel electrode 109 or the air electrode 113) may be thickly formed instead of the substrate so as to double as the substrate.

First, a cylindrical cell stack using a substrate tube will be described as an example according to this embodiment with reference to FIG. When the substrate tube is not used, for example, the fuel electrode 109 may be formed thick and used as the substrate tube, and the use of the substrate tube is not limited. Further, although the substrate tube in this embodiment is described as having a cylindrical shape, the substrate tube may be cylindrical, and the cross section is not necessarily limited to a circular shape, and may be an elliptical shape, for example. A cell stack such as a flat tubular in which the peripheral surface of the cylinder is vertically crushed may be used.

Here, FIG. 1 shows one aspect of the cell stack according to this embodiment. The cell stack 101 includes, for example, a cylindrical base tube 103, a plurality of fuel cells 105 formed on the outer peripheral surface of the base tube 103, and an interconnector 107 formed between adjacent fuel cells 105. . The fuel cell 105 is formed by laminating a fuel electrode 109, a solid electrolyte membrane 111, and an air electrode 113. As shown in FIG.

In addition, the cell stack 101 is connected to the air electrode 113 of the fuel cell 105 formed at one end of the base tube 103, which is the most end in the axial direction of the base tube 103, among the plurality of fuel cells 105 formed on the outer peripheral surface of the base tube 103. , a lead film 115 electrically connected via an interconnector 107, and a lead film 115 electrically connected to the fuel electrode 109 of the fuel cell 105 formed at the other end of the most end.

The substrate tube 103 is made of a porous material, such as CaO-stabilized _ZrO2 (CSZ), a mixture of CSZ and nickel oxide (NiO) (CSZ+NiO), or _{Y2O3 -} stabilized _ZrO2 (YSZ), or The main component is MgAl ₂ O ₄ or the like. The substrate tube 103 supports the fuel cell 105, the interconnector 107, and the lead film 115, and also allows the fuel gas supplied to the inner peripheral surface of the substrate tube 103 to pass through the substrate tube 103 through the pores of the substrate tube 103. is diffused to the fuel electrode 109 formed on the outer peripheral surface of the .

The fuel electrode 109 is composed of a composite oxide of Ni and a zirconia-based electrolyte material, such as Ni/YSZ. The thickness of the fuel electrode 109 is 50 μm to 250 μm, and the fuel electrode 109 may be formed by screen printing slurry. In this case, the fuel electrode 109 has Ni, which is a component of the fuel electrode 109, catalyzing the fuel gas. This catalytic action causes the fuel gas supplied through the substrate tube 103, such as a mixed gas of methane (CH ₄ ) and water vapor, to react and reform into hydrogen (H ₂ ) and carbon monoxide (CO). It is.

In addition, the fuel electrode 109 combines hydrogen (H ₂ ) and carbon monoxide (CO) obtained by reforming and oxygen ions (O ²⁻ ) supplied through the solid electrolyte membrane 111 with the solid electrolyte membrane 111. are electrochemically reacted near the interface to produce water (H ₂ O) and carbon dioxide (CO ₂ ). At this time, the fuel cell 105 generates electricity by electrons released from the oxygen ions.

Fuel gases that can be supplied to and used by the fuel electrode 109 of the solid oxide fuel cell include hydrogen (H ₂ ), carbon monoxide (CO), hydrocarbon gases such as methane (CH ₄ ), city gas, and natural gas. In addition, gasification gas produced by gasification equipment from carbon-containing raw materials such as petroleum, methanol, and coal can be used.

The solid electrolyte membrane 111 is mainly made of YSZ, which has airtightness and high oxygen ion conductivity at high temperatures. This solid electrolyte membrane 111 moves oxygen ions (O ²⁻ ) generated at the air electrode 113 to the fuel electrode 109 . The thickness of the solid electrolyte membrane 111 located on the surface of the fuel electrode 109 is 10 μm to 100 μm, and the solid electrolyte membrane 111 may be formed by screen printing slurry.

The air electrode 113 is made of, for example, LaSrMnO ₃ -based oxide or LaCoO ₃ -based oxide, and slurry is applied to the air electrode 113 by screen printing or using a dispenser. This air electrode 113 generates oxygen ions (O ²⁻ ) by dissociating oxygen in an oxidizing gas such as supplied air near the interface with the solid electrolyte membrane 111 .

The air electrode 113 can also have a two-layer structure. In this case, the air electrode layer (intermediate air electrode layer) on the solid electrolyte membrane 111 side exhibits high ionic conductivity and is composed of a material with excellent catalytic activity. The cathode layer (cathode conductive layer) on the cathode intermediate layer may be composed of a perovskite oxide represented by Sr- and Ca-doped LaMnO ₃ . By doing so, power generation performance can be further improved.

The oxidizing gas is a gas containing approximately 15% to 30% oxygen, and air is typically suitable, but other than air, mixed gas of combustion exhaust gas and air, mixed gas of oxygen and air is available.

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, L is a lanthanide element) such as SrTiO ₃ system, and the slurry is screen-printed. do. The interconnector 107 is a dense film that prevents mixing of the fuel gas and the oxidizing gas.

In addition, the interconnector 107 has stable durability and electrical conductivity in both an oxidizing atmosphere and a reducing atmosphere. This interconnector 107 electrically connects the air electrode 113 of one fuel cell 105 and the fuel electrode 109 of the other fuel cell 105 in the adjacent fuel cells 105, and connects the adjacent fuel cells 105 to each other. are connected in series.

The lead film 115 is required to have electronic conductivity and to have a coefficient of thermal expansion close to that of other materials constituting the cell stack 101. Therefore, the combination of Ni such as Ni/YSZ and the zirconia-based electrolyte material is preferable. It is composed of M1-xLxTiO ₃ (M is an alkaline earth metal element, L is a lanthanide element) such as a composite material or SrTiO ₃ system. This lead film 115 guides the DC power generated by the plurality of fuel cells 105 connected in series by the interconnector 107 to near the end of the cell stack 101 .

The substrate tube 103 on which the slurry film of the fuel electrode 109, the solid electrolyte membrane 111 and the interconnector 107 is formed is co-sintered in the atmosphere. The sintering temperature is specifically 1350°C to 1450°C. Next, the substrate tube 103 having the slurry film of the air electrode 113 formed on the co-sintered substrate tube 103 is sintered in the air. The sintering temperature is specifically set to 1100.degree. C. to 1250.degree. The sintering temperature here is lower than the co-sintering temperature after forming the base tube 103 to the interconnector 107 .

Next, an SOFC module and an SOFC cartridge according to this embodiment will be described with reference to FIGS. 2 and 3. FIG. Here, FIG. 2 shows one aspect of the SOFC module according to this embodiment. Further, FIG. 3 shows a cross-sectional view of one aspect of the SOFC cartridge according to the present embodiment.

The SOFC module (fuel cell module) 201 includes, for example, a plurality of SOFC cartridges (fuel cell cartridges) 203 and a pressure vessel 205 that houses the plurality of SOFC cartridges 203, as shown in FIG. Although the cylindrical SOFC cell stack 101 is illustrated in FIG. 2, it is not necessarily limited to this, and may be, for example, a flat cell stack.

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

The fuel gas supply pipe 207 is provided outside the pressure vessel 205 and is connected to a fuel gas supply unit that supplies fuel gas with a predetermined gas composition and a predetermined flow rate corresponding to the power generation amount of the SOFC module 201. It is connected to the fuel gas supply branch pipe 207a. The fuel gas supply pipe 207 branches and guides a predetermined flow rate of fuel gas supplied from the above-described fuel gas supply section to a plurality of fuel gas supply branch pipes 207a.

Further, the fuel gas supply branch pipe 207 a is connected to the fuel gas supply pipe 207 and also to the plurality of SOFC cartridges 203 . The fuel gas supply branch pipe 207a guides the fuel gas supplied from the fuel gas supply pipe 207 to the plurality of SOFC cartridges 203 at a substantially uniform flow rate, thereby substantially uniforming the power generation performance of the plurality of SOFC cartridges 203. .

The fuel gas discharge branch pipe 209 a is connected to the plurality of SOFC cartridges 203 and to the fuel gas discharge pipe 209 . This fuel gas discharge branch pipe 209 a guides the exhaust fuel gas discharged from the SOFC cartridge 203 to the fuel gas discharge pipe 209 . Further, the fuel gas discharge pipe 209 is connected to a plurality of fuel gas discharge branch pipes 209 a and part of it is arranged outside the pressure vessel 205 . This fuel gas discharge pipe 209 guides the exhaust fuel gas discharged from the fuel gas discharge branch pipe 209 a at a substantially uniform flow rate to the outside of the pressure vessel 205 .

Since the pressure vessel 205 is operated at an internal pressure of 0.1 MPa to approximately 3 MPa and an internal temperature of from atmospheric temperature to approximately 550° C., it has durability and corrosion resistance to oxidants such as oxygen contained in the oxidizing gas. The materials we have are used. For example, a stainless steel material such as SUS304 is suitable.

Here, in the present embodiment, a mode in which a plurality of SOFC cartridges 203 are grouped and housed in the pressure vessel 205 is described, but the present invention is not limited to this. It can also be configured to be housed in the container 205 .

As shown in FIG. 3, the SOFC cartridge 203 includes a plurality of cell stacks 101, a power generation chamber 215, a fuel gas supply header 217, a fuel gas discharge header 219, an oxidizing gas supply header (air supply header) 221, and an oxidizing gas discharge header 223 . The SOFC cartridge 203 also includes an upper tube sheet 225a, a lower tube sheet 225b, an upper heat insulator 227a, and a lower heat insulator 227b.

In the present embodiment, the SOFC cartridge 203 has the fuel gas supply header 217, the fuel gas discharge header 219, the oxidizing gas supply header 221, and the oxidizing gas discharge header 223 arranged as shown in FIG. , the fuel gas and the oxidizing gas flow inside and outside the cell stack 101 facing each other. Alternatively, the oxidizing gas may flow in a direction perpendicular to the longitudinal direction of the cell stack 101 .

The power generation chamber 215 is a region formed between the upper heat insulator 227a and the lower heat insulator 227b. The power generation chamber 215 is a region in which the fuel cells 105 of the cell stack 101 are arranged, and is a region in which the fuel gas and the oxidizing gas are electrochemically reacted to generate power. Further, the temperature near the center of the cell stack 101 in the longitudinal direction of the power generation chamber 215 is monitored by a temperature measurement unit (temperature sensor, thermocouple, etc.) becomes a high-temperature atmosphere.

The fuel gas supply header 217 is an area surrounded by the upper casing 229a and the upper tube plate 225a of the SOFC cartridge 203. The fuel gas supply branch pipe 207a is connected to the fuel gas supply branch pipe 207a 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 tube plate 225a and the sealing member 237a. is introduced into the substrate tubes 103 of the plurality of cell stacks 101 at a substantially uniform flow rate to substantially uniform the power generation performance of the plurality of cell stacks 101 .

The fuel gas discharge header 219 is an area surrounded by the lower casing 229b and the lower tube plate 225b of the SOFC cartridge 203. The fuel gas discharge branch pipe 209a (not shown) is opened by the fuel gas discharge hole 231b provided in the lower casing 229b. is communicated with. In addition, the plurality of cell stacks 101 are joined to the lower tube plate 225b and the sealing member 237b, and the fuel gas discharge header 219 passes through the inside of the base tube 103 of the plurality of cell stacks 101 to the fuel gas discharge header 219. The exhaust fuel gas supplied to is collected and led to the fuel gas discharge branch pipe 209a through the fuel gas discharge hole 231b.

An oxidizing gas having a predetermined gas composition and a predetermined flow rate corresponding to the amount of power generated by the SOFC module 201 is branched to the oxidizing gas supply branch pipes and supplied to the plurality of SOFC cartridges 203 . The oxidizing gas supply header 221 is an area surrounded by the lower casing 229b, the lower tube sheet 225b, and the lower heat insulator 227b of the SOFC cartridge 203, and is supplied by the oxidizing gas supply holes 233a provided on the side surface of the lower casing 229b. , is communicated with an oxidizing gas supply branch pipe (not shown). The oxidizing gas supply header 221 receives a predetermined flow rate of oxidizing gas supplied from an oxidizing gas supply branch pipe (not shown) through an oxidizing gas supply hole 233a to generate power through an oxidizing gas supply gap 235a, which will be described later. It leads to chamber 215 .

The oxidizing gas discharge header 223 is an area surrounded by the upper casing 229a, the upper tube plate 225a, and the upper heat insulator 227a of the SOFC cartridge 203, and is discharged by the oxidizing gas discharge holes 233b provided on the side surface of the upper casing 229a. , is communicated with an oxidizing gas discharge branch pipe (not shown). The oxidizing gas discharge header 223 discharges the exhaust oxidizing gas supplied from the power generation chamber 215 to the oxidizing gas discharge header 223 through an oxidizing gas discharge gap 235b, which will be described later, through the oxidizing gas discharge hole 233b. It leads to an oxidizing gas discharge branch pipe (not shown).

The upper tube sheet 225a is positioned between the top plate of the upper casing 229a and the upper heat insulator 227a so that the upper tube sheet 225a, the top plate of the upper casing 229a, and the upper heat insulator 227a are substantially parallel to each other. is fixed to the side plate of the The upper tube plate 225a has a plurality of holes corresponding to the number of cell stacks 101 provided in the SOFC cartridge 203, and the cell stacks 101 are inserted into the holes. The upper tube plate 225a airtightly supports one end of each of the plurality of cell stacks 101 via one or both of a sealing member 237a and an adhesive member, and also includes a fuel gas supply header 217 and an oxidizing gas discharge header. 223.

The upper heat insulator 227a is arranged at the lower end of the upper casing 229a so that the upper heat insulator 227a, the top plate of the upper casing 229a, and the upper tube plate 225a are substantially parallel, and are fixed to the side plates of the upper casing 229a. there is Also, the upper heat insulator 227 a is provided with a plurality of holes corresponding to the number of cell stacks 101 provided in the SOFC cartridge 203 . The diameter of this hole is set larger than the outer diameter of the cell stack 101 . The upper heat insulator 227a has an oxidizing gas discharge gap 235b formed between the inner surface of this hole and the outer surface of the cell stack 101 inserted through the upper heat insulator 227a.

The upper heat insulator 227a partitions the power generation chamber 215 and the oxidizing gas discharge header 223. When the atmosphere around the upper tube sheet 225a becomes hot, its strength decreases and corrosion due to the oxidizing agent contained in the oxidizing gas occurs. suppress the increase. The upper tube sheet 225a and the like are made of a metal material with high temperature durability such as Inconel. It prevents thermal deformation. The upper heat insulator 227a guides the exhaust oxidizing gas, which has passed through the power generation chamber 215 and is exposed to high temperatures, to the oxidizing gas exhaust header 223 through the oxidizing gas exhaust gap 235b.

According to this embodiment, due to the structure of the SOFC cartridge 203 described above, the fuel gas and the oxidizing gas flow inside and outside the cell stack 101 facing each other. As a result, the exhaust oxidizing gas undergoes heat exchange with the fuel gas supplied to the power generation chamber 215 through the interior of the substrate tube 103, and the upper tube sheet 225a made of a metal material is prevented from buckling. It is cooled to a temperature at which it does not deform and is supplied to the oxidizing gas discharge header 223 . Further, the temperature of the fuel gas is raised by heat exchange with the exhaust oxidizing gas discharged from the power generation chamber 215 and supplied to the power generation chamber 215 . As a result, the fuel gas preheated to a temperature suitable for power generation can be supplied to the power generation chamber 215 without using a heater or the like.

The lower tube sheet 225b is placed between the bottom plate of the lower casing 229b and the lower heat insulator 227b, and on the side plate of the lower casing 229b so that the bottom plate of the lower tube sheet 225b, the bottom plate of the lower casing 229b, and the lower heat insulator 227b are substantially parallel to each other. Fixed. The lower tube plate 225b has a plurality of holes corresponding to the number of cell stacks 101 provided in the SOFC cartridge 203, and the cell stacks 101 are inserted into the holes. The lower tube sheet 225b airtightly supports the other ends of the plurality of cell stacks 101 via one or both of the sealing member 237b and the adhesive member, and also includes the fuel gas discharge header 219 and the oxidizing gas supply header. 221.

The lower heat insulator 227b is arranged at the upper end of the lower casing 229b so that the bottom plate of the lower heat insulator 227b, the bottom plate of the lower casing 229b, and the lower tube sheet 225b are substantially parallel, and is fixed to the side plate of the lower casing 229b. . A plurality of holes corresponding to the number of cell stacks 101 provided in the SOFC cartridge 203 are provided in the lower heat insulator 227b. The diameter of this hole is set larger than the outer diameter of the cell stack 101 . The lower heat insulator 227b has an oxidizing gas supply gap 235a formed between the inner surface of this hole and the outer surface of the cell stack 101 inserted through the lower heat insulator 227b.

The lower heat insulator 227b partitions the power generation chamber 215 and the oxidizing gas supply header 221. When the atmosphere around the lower tube sheet 225b becomes hot, its strength decreases and corrosion due to the oxidizing agent contained in the oxidizing gas occurs. suppress the increase. The lower tube sheet 225b and the like are made of a metal material such as Inconel that is resistant to high temperatures. It prevents. The lower heat insulator 227b guides the oxidizing gas supplied to the oxidizing gas supply header 221 to the power generation chamber 215 through the oxidizing gas supply gap 235a.

According to this embodiment, due to the structure of the SOFC cartridge 203 described above, the fuel gas and the oxidizing gas flow inside and outside the cell stack 101 facing each other. As a result, the exhaust fuel gas that has passed through the interior of the substrate tube 103 and the power generation chamber 215 is heat-exchanged with the oxidizing gas supplied to the power generation chamber 215, and the lower tube plate 225b made of a metal material is produced. etc. are cooled to a temperature at which they are not deformed such as buckling and supplied to the fuel gas discharge header 219 . Also, the oxidizing gas is heated by heat exchange with the exhaust fuel gas and supplied to the power generation chamber 215 . As a result, the oxidizing gas heated to a temperature required for power generation can be supplied to the power generation chamber 215 without using a heater or the like.

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 the lead films 115 made of Ni/YSZ or the like provided in the plurality of fuel cells 105, and then is supplied to the collector rod (non-contact) of the SOFC cartridge 203. ) through a current collecting plate (not shown) and taken out of each SOFC cartridge 203 .

The DC power led to the outside of the SOFC cartridge 203 by the current collecting rod is connected to the power generated by each SOFC cartridge 203 in a predetermined series number and parallel number, and is led out to the outside of the SOFC module 201, A power conversion device (such as an inverter) such as a power conditioner (not shown) converts the AC power into predetermined AC power, which is supplied to a power supply destination (for example, a load facility or a power system).

A schematic configuration of a fuel cell system 310 according to an embodiment of the present disclosure will be described.
FIG. 4 is a schematic configuration diagram showing a schematic configuration of a fuel cell system 310 according to one embodiment of the present disclosure. As shown in FIG. 4 , the fuel cell system 310 has a turbocharger 411 and an SOFC 313 . The SOFC 313 is configured by combining one or more SOFC modules (not shown), and is hereinafter simply referred to as "SOFC". This fuel cell system 310 generates power using an SOFC 313 . The fuel cell system 310 is controlled by the controller 20 .

The turbocharger 411 includes a compressor 421 and a turbine 423, and the compressor 421 and the turbine 423 are connected by a rotating shaft 424 so as to rotate integrally. The compressor 421 is rotationally driven by the rotation of a turbine 423 which will be described later. This embodiment is an example using air as the oxidizing gas, and the compressor 421 compresses the air A taken in from the air intake line 325 .

Compressor 421 constituting turbocharger 411 takes in air A and compresses it, and supplies compressed air A as oxidizing gas A2 to air electrode 113 of the SOFC. The exhaust oxidizing gas A3 after being used in the chemical reaction for power generation in the SOFC is sent to the catalytic combustor (combustor) 422 via the exhaust oxidizing gas line 333, and is used in the SOFC for chemical reaction for power generation. The exhaust fuel gas L3 after being used for the reaction is pressurized by the recirculation blower 348, and part of it is recirculated and supplied to the fuel gas line 341 through the fuel gas recirculation line 349, while the other part is exhausted. It is sent to catalytic combustor 422 via fuel gas line 343 .

In this way, the exhaust oxidizing gas A3 and part of the exhaust fuel gas L3 are supplied to the catalytic combustor 422, and are stably burned at a relatively low temperature using a combustion catalyst in a catalytic combustion section (not shown) (described later). ), generating combustion gas G.

The catalytic combustor 422 mixes the exhaust fuel gas L3, the exhaust oxidizing gas A3, and, if necessary, the fuel gas L1, and combusts them in the catalytic combustion section to generate the combustion gas G. The catalytic combustion section is filled with a combustion catalyst containing, for example, platinum or palladium as a main component, enabling stable combustion at a relatively low temperature and low oxygen concentration. Combustion gas G is supplied to turbine 423 through combustion gas supply line 328 . The turbine 423 is rotationally driven by adiabatic expansion of the combustion gas G, and the combustion gas G is discharged from the flue gas line 329 .

The fuel gas L1 is supplied to the catalytic combustor 422 with the flow rate controlled by the control valve 352 . The fuel gas L1 is a combustible gas, such as gas obtained by vaporizing liquefied natural gas (LNG), natural gas, city gas, hydrogen (H ₂ ), carbon monoxide (CO), methane (CH ₄ ), and the like. Hydrocarbon gas and gas produced by a gasification facility for carbonaceous raw materials (petroleum, coal, etc.) are used. The fuel gas means a fuel gas whose calorific value is adjusted to be substantially constant in advance.

The combustion gas G heated by combustion in the catalytic combustor 422 is sent to the turbine 423 constituting the turbocharger 411 through the combustion gas supply line 328, and rotates the turbine 423 to generate rotational power. By driving the compressor 421 with this rotational power, the air A taken in from the air intake line 325 is compressed to generate compressed air. Since the turbocharger 411 can generate the power of the rotary device that compresses and blows the oxidizing gas (air), the required power can be reduced and the power generation efficiency of the power generation system can be improved.

A heat exchanger (regenerative heat exchanger) 430 exchanges heat between the exhaust gas discharged from the turbine 423 and the oxidizing gas A2 supplied from the compressor 421 . After being cooled by heat exchange with the oxidizing gas A2, the exhaust gas is discharged to the outside through a chimney (not shown) via an exhaust heat recovery device 442, for example.

The SOFC 313 is supplied with the fuel gas L1 as a reducing agent and the oxidizing gas A2 as an oxidizing agent, and reacts at a predetermined operating temperature to generate power. The SOFC 313 is composed of an SOFC module (not shown) and accommodates an assembly of a plurality of cell stacks provided in a pressure vessel of the SOFC module. A membrane 111 is provided.

The SOFC 313 generates power when the air electrode 113 is supplied with the oxidizing gas A2 and the fuel electrode 109 is supplied with the fuel gas L1. and supplied to power demand destinations.

The SOFC 313 is connected to an oxidizing gas supply line 331 that supplies the oxidizing gas A2 compressed by the compressor 421 to the air electrode 113 . An oxidizing gas A2 is supplied to an oxidizing gas introduction portion (not shown) of the air electrode 113 through the oxidizing gas supply line 331 . The oxidizing gas supply line 331 is provided with a control valve (oxidizing gas control valve) 335 for adjusting the flow rate of the supplied oxidizing gas A2. In the heat exchanger 430, the oxidizing gas A2 is heat-exchanged with the combustion gas discharged from the flue gas line 329 to raise its temperature.

Furthermore, the oxidizing gas supply line 331 is provided with a heat exchanger bypass line 332 that bypasses the heat transfer portion of the heat exchanger 430 . A control valve 336 is provided in the heat exchanger bypass line 332 so that the bypass flow rate of the oxidizing gas can be adjusted. By controlling the opening degrees of the control valve 335 and the control valve 336, the flow ratio of the oxidizing gas passing through the heat exchanger 430 and the oxidizing gas bypassing the heat exchanger 430 is adjusted, and supplied to the SOFC 313. The temperature of the oxidizing gas A2 is adjusted.

The temperature of the oxidizing gas A2 supplied to the SOFC 313 maintains the temperature at which the fuel gas of the SOFC 313 and the oxidizing gas are electrochemically reacted to generate power, and the temperature of each of the SOFC modules (not shown) constituting the SOFC 313 is maintained. The upper temperature limit is limited so as not to damage the material of the components.

The SOFC 313 is connected to an exhaust oxidizing gas line 333 that supplies the exhaust oxidizing gas A3 exhausted from the air electrode 113 to the turbine 423 via the catalytic combustor 422 . The exhaust oxidizing gas line 333 is provided with an exhaust air cooler 351 . Specifically, in the exhaust oxidizing gas line 333, an exhaust air cooler 351 is provided upstream of an orifice 441, which will be described later. The exhaust oxidizing gas A3 is cooled.

Further, the exhaust oxidizing gas line 333 is provided with a pressure loss portion. In this embodiment, an orifice 441 is provided as a pressure loss portion. The orifice 441 applies pressure loss to the exhaust oxidizing gas A3 flowing through the exhaust oxidizing gas line 333 . Note that the pressure loss portion is not limited to the orifice 441, and for example, a throttle portion such as a venturi tube may be provided, and any means capable of adding pressure loss to the exhaust oxidizing gas A3 can be used. .

Further, as the pressure loss portion, for example, an additional burner may be provided. The additional burner generates a pressure loss in the exhaust oxidizing gas, and when combustion exceeding the combustion capacity of the catalytic combustor 422 is required, the additional fuel can be burned, so the exhaust oxidizing gas It is possible to supply a sufficient amount of heat to

In the fuel cell system 310, the pressure difference between the air electrode 113 side and the fuel electrode 109 side is controlled by a control valve 347 provided in the exhaust fuel gas line 343 so that the pressure difference is within a predetermined range. By adding a pressure loss to the exhaust oxidizing gas line 333, it is possible to ensure an operating differential pressure necessary for stably controlling the regulating valve 347 provided in the exhaust fuel gas line 343.

Further, the exhaust oxidizing gas line 333 is not provided with a vent system and a vent valve for discharging the exhaust oxidizing gas A3 to the atmosphere (outside the system). For example, in the case of a power generation system that combines an SOFC, an exhaust oxidizing gas A3 discharged from the air electrode 113, and a gas turbine (for example, a micro gas turbine) that burns the exhaust fuel gas L3 discharged from the fuel electrode 109, starting The pressure state of the oxidizing gas supplied to the air electrode 113 may change in response to changes in the state of the micro gas turbine, such as when the micro gas turbine is on or off.

Furthermore, there is a possibility that differential pressure control between the fuel electrode 109 and the air electrode 113 will be out of order due to sudden pressure fluctuations. As a result, protective measures for the micro gas turbine may be required. Therefore, a vent system and a vent valve are required to release the exhaust oxidizing gas A3 to the outside of the system such as the atmosphere.

In this embodiment, the turbocharger 411 is used, and since there is no generator connected to the rotating shaft and no load is borne, there is no possibility that the load will disappear at the time of a trip, resulting in excessive rotation and a sudden increase in pressure. Since the differential pressure state can be stably controlled by the regulating valve 347, a mechanism (vent system and vent valve) for releasing the exhaust oxidizing gas A3 to the atmosphere can be omitted.

The SOFC 313 further includes a fuel gas line 341 that supplies the fuel gas L1 to a fuel gas introduction portion (not shown) of the fuel electrode 109, and an exhaust fuel gas L3 that has been used in the reaction at the fuel electrode 109 and discharged. An exhaust fuel gas line 343 that supplies a turbine 423 is connected via a container 422 . The fuel gas line 341 is provided with a control valve (fuel gas control valve) 342 for adjusting the flow rate of the fuel gas L1 supplied to the fuel electrode 109 .

A recirculation blower 348 is provided in the exhaust fuel gas line 343 . Further, the exhaust fuel gas line 343 is provided with a regulating valve 347 for adjusting the flow rate of part of the exhaust fuel gas L3 supplied to the catalytic combustor 422 . In other words, the regulating valve 347 adjusts the pressure state of the exhaust fuel gas L3. Therefore, as will be described later, the differential pressure between the fuel electrode 109 and the air electrode 113 can be adjusted by controlling the regulating valve 347 with the controller 20 .

The exhaust fuel gas line 343 is connected downstream of the recirculation blower 348 with an exhaust fuel gas release line 350 for releasing the exhaust fuel gas L3 to the atmosphere (outside the system). A cutoff valve (fuel vent valve) 346 is provided in the exhaust fuel gas release line 350 . That is, by opening the shutoff valve 346, part of the exhaust fuel gas L3 in the exhaust fuel gas line 343 can be released from the exhaust fuel gas release line 350.

Excessive pressure can be quickly adjusted by discharging the exhaust fuel gas L3 to the outside of the system. A fuel gas recirculation line 349 for recirculating the exhaust fuel gas L3 to the fuel gas introduction portion of the fuel electrode 109 of the SOFC 313 is connected to the fuel gas line 343 .

Furthermore, the fuel gas recirculation line 349 is provided with a pure water supply line 361 for supplying pure water for reforming the fuel gas L1 to the fuel electrode 109 . A pump 362 is provided in the pure water supply line 361 . The amount of pure water supplied to the fuel electrode 109 is adjusted by controlling the discharge flow rate of the pump 362 . Since water vapor is generated at the fuel electrode during power generation, the exhaust fuel gas L3 in the exhaust fuel gas line 343 contains water vapor. The flow rate of pure water supplied through the pure water supply line 361 can be reduced or cut off.

Next, a configuration for releasing the oxidizing gas discharged from the compressor 421 will be described. Specifically, in the oxidizing gas supply line 331 on the downstream side of the compressor 421, an oxidizing gas blow line through which the oxidizing gas bypasses the heat exchanger 430 and is discharged outside the system (outside). 444 is provided. The oxidizing gas blow line 444 has one end connected to the upstream side of the heat exchanger 430 of the oxidizing gas supply line 331 and the other end connected to the heat exchanger of the flue gas line 329 downstream of the turbine 423 . 430 downstream.

A blow valve (control valve) 445 is provided in the oxidizing gas blow line 444 . That is, by opening the blow valve 445, part of the oxidizing gas discharged from the compressor 421 is discharged to the atmosphere outside the system through a chimney (not shown) via the oxidizing gas blow line 444. be.

Next, a configuration used for starting up the fuel cell system 310 will be described. The oxidizing gas supply line 331 is provided with a control valve 451 on the downstream side of the connection point with the oxidizing gas blow line 444. On the downstream side of the control valve 451 (upstream side of the heat exchanger 430), a starting A starter air line 454 having a blower 452 for supplying starter air and a control valve 453 is connected. When starting up the fuel cell system 310 , while the blower 452 supplies start-up air to the oxidizing gas supply line 331 , the oxidizing gas from the compressor 421 is switched by the control valves 451 and 453 .

In the oxidizing gas supply line 331, a starting air heating line (oxidizing gas heating line) 455 is connected downstream of the heat exchanger 430 (upstream of the control valve 335). It is connected to the exhaust oxidizing gas line 333 on the downstream side of the exhaust air cooler 351 via a control valve (heating control valve) 457 and is connected to the oxidizing gas supply line 331 (inlet side of the air electrode 113) via a control valve (heating control valve) 457. It is

In addition, the starting air heating line 455 is provided with a starting heater 458, the fuel gas L1 is supplied via a control valve 459, and the oxidizing gas flowing through the starting air heating line 455 is heated. done. Note that the control valve 457 adjusts the flow rate of the oxidizing gas supplied to the start-up heater 458 and controls the temperature of the oxidizing gas supplied to the SOFC 313 . Thus, the starting air heating line 455 , the control valve 457 , and the starting heater 458 function as a heating unit that heats the oxidizing gas flowing through the oxidizing gas supply line 331 .

The fuel gas L1 is also supplied to the air electrode 113 via the control valve 460 . For example, when the SOFC 313 is started, the fuel gas L1 is supplied from the downstream side of the control valve 457 in the starting air heating line 455 to the air electrode 113, and the temperature of the power generation chamber is increased by catalytic combustion. The flow rate of the fuel gas L1 supplied to the pole 113 is controlled.

The control device 20 performs start-up control for the fuel cell system 310 . In a fuel cell system in which an SOFC and a turbocharger 411 are combined, the turbocharger 411 cannot be started independently unlike, for example, a micro gas turbine. Therefore, it is necessary to supply start-up air from the outside. Therefore, at the time of start-up, it is necessary to switch the supply of the oxidizing gas to the SOFC from the starting air to the oxidizing gas compressed by the compressor 421 of the turbocharger 411 . Therefore, the control device 20 controls the control valve 451 and the blow valve 445 .

FIG. 5 is a diagram showing an example of the hardware configuration of the control device 20 according to this embodiment.
As shown in FIG. 5, the control device 20 is a computer system (computer system). A RAM (Random Access Memory) 13 functioning as a work area, a hard disk drive (HDD) 14 as a large-capacity storage device, and a communication unit 15 for connecting to a network or the like. A solid state drive (SSD) may be used as the mass storage device. These units are connected via a bus 18 .

Further, the control device 20 may include an input section such as a keyboard and a mouse, and a display section such as a liquid crystal display device for displaying data. Note that the storage medium for storing programs and the like executed by the CPU 11 is not limited to the ROM 12 . For example, other auxiliary storage devices such as magnetic disks, magneto-optical disks, and semiconductor memories may be used.

A series of processes for realizing various functions to be described later is recorded in the hard disk drive 14 or the like in the form of a program. As a result, various functions to be described later are realized. In addition, the program is pre-installed in the ROM 12 or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. etc. may be applied. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like.

Next, a method for starting the fuel cell system 310 will be described with reference to the drawings. FIG. 6 is a flowchart showing a method for starting the fuel cell system 310 of this embodiment. Each process shown in FIG. 6 is executed by control device 20 controlling each part of fuel cell system 310 .

FIG. 7 is a graph showing changes in the fuel gas L1 supplied to the catalytic combustor 422. As shown in FIG. FIG. 8 is a graph showing changes in the degree of opening of the blow valve 445. As shown in FIG. FIG. 9 is a graph showing changes in the flow rate of the fuel gas L1 supplied to the fuel electrode 109. As shown in FIG. FIG. 10 is a graph showing changes in the temperature of the generator chamber 215. As shown in FIG. FIG. 11 is a graph showing changes in the rotational speed of turbine 423. As shown in FIG. FIG. 12 is a graph showing changes in the flow rate of the oxidizing gas supplied to the power generation chamber 215. As shown in FIG.

In step S101, the control device 20 executes a system purge. The control device 20 opens the control valve 443, the control valve 453, the blow valve 445, the control valve 335, the control valve 456, and the adjustment valve 347, and closes the other valves. Nitrogen is vented through the control valve 443 to the fuel electrode 109 side. Then, the blower 452 is activated, and the control valve 453 and the control valve 335 are open, so that the activation air is supplied to the air electrode 113 side and ventilated. This purges SOFC 313 .

By opening control valve 456 , start-up air bypasses SOFC 313 and is vented to catalytic combustor 422 via start-up heater 458 . This causes the turbine 423 to start rotating with the starting air. As the turbine 423 rotates, the coaxially connected compressor 421 starts rotating.

The compressor 421 compresses the oxidizing gas, and the compressed oxidizing gas is discharged out of the system through the oxidizing gas blow line 444 by opening the blow valve 445 . Surging of the compressor 421 is prevented by discharging to the outside of the system. Surging is an abnormal state in which the pressure at the outlet of the compressor 421 rises and the compressor 421 stalls, compressed air flows backward, or the like. Note that differential pressure control between the fuel electrode 109 and the air electrode 113 is performed by a regulating valve 347 .

In step S<b>102 , the control device 20 ignites the start-up heater 458 . The control device 20 opens the control valve 453, the blow valve 445, the control valve 335, the control valve 456, the control valve 459, and the adjustment valve 347, and closes the other valves. Also, the control valve 457 may be opened depending on the situation. That is, after the purge is completed, the control valve 456 is throttled and the control valve 335 is opened to bypass the SOFC 313 and reduce the flow rate of the start-up air supplied to the catalytic combustor 422, thereby increasing the start-up air supplied to the SOFC 313. Let

Differential pressure control between the fuel electrode 109 and the air electrode 113 is performed by the regulating valve 347 . Then, a part of the fuel gas L1 is supplied from the control valve 459 to ignite the starting heater 458, thereby raising the temperature of the starting air. As a result, the inlet temperature of the turbine 423 rises and the system internal pressure rises.

In step S<b>103 , the control device 20 ignites the catalytic combustor 422 . The control device 20 opens the control valve 453, the blow valve 445, the control valve 335, the control valve 456, the control valve 459, the control valve 352, and the adjustment valve 347, and closes the other valves. To the catalytic combustor 422, starting air of about 400° C. to 500° C. sent with the control valve 456 slightly opened (about 20% of the amount of starting air) and the SOFC 313 via the control valve 457 It is supplied by being mixed with the sent starting air. This increases the temperature of the catalytic combustor 422 .

When the inlet temperature of catalytic combustor 422 reaches a specified temperature (eg, 300° C. to 400° C.), fuel gas L 1 is supplied to catalytic combustor 422 through control valve 352 . Note that when the fuel gas L1 is introduced, the control valve 352 is temporarily held at a specified opening, and ignition is confirmed by observing the temperature rise at the outlet of the catalytic combustor 422 . Then, the control valve 352 is subjected to opening degree control (flow rate control of the fuel gas L1) according to the outlet temperature of the catalytic combustor 422 .

In step S<b>104 , the control device 20 causes the turbocharger 411 to become independent. The control device 20 opens the control valve 342, the control valve 453, the control valve 335, the control valve 456, the control valve 459, the control valve 352, and the adjustment valve 347, and closes the other valves. At time T1, the controller 20 opens the fuel gas supply control valve 342 to supply the fuel gas L1 to the fuel electrode 109, and drives the pump 362 of the pure water supply line 361 to supply pure water to the fuel electrode 109. supply to The blow valve 445 is controlled to close, and the control valve 451 is controlled to open. That is, when the self-sustainability requirement of the turbocharger 411 is satisfied, the blow valve 445 is gradually closed and the control valve 451 is gradually opened.

The independence requirement is when the rotation speed of the turbocharger 411 reaches a predetermined value or more and the temperature of the combustion gas G supplied to the turbine 423 (the temperature at the outlet of the catalytic combustor 422) reaches a predetermined temperature or more. By gradually closing the blow valve 445, the flow rate of the oxidizing gas discharged to the outside of the system is reduced. When the blow valve 445 is fully closed and the control valve 451 reaches a predetermined degree of opening (for example, fully open), the control valve 453 is closed, the blower 452 is stopped, and the supply of starting air is terminated.

It is preferable that the supply amount of the starting air is increased in accordance with the increase in the rotation speed of the turbocharger 411 and the increase in the outlet temperature of the catalytic combustor 422 . As a result, the turbine 423 is rotated by the oxidizing gas compressed by the compressor 421, and the compressor 421 is rotationally driven, so that the turbocharger 411 enters a self-sustaining state.

After turbocharger 411 becomes independent, controller 20 controls each valve to continue raising the temperature. Controller 20 controls the inlet temperature of catalytic combustor 422 by adjusting the temperature of the oxidizing gas with control valve 456 . The control device 20 also controls the outlet temperature of the catalytic combustor 422 by adjusting the flow rate of the fuel gas L1 with the control valve 352 .

The control device 20 also controls the flow rate of the oxidizing gas passing through the start-up heater 458 using the control valve 457 . The control device 20 also controls the outlet temperature of the heater 458 for startup by adjusting the flow rate of the fuel gas L1 supplied to the heater 458 for startup by the control valve 459 . In addition, the control device 20 sets the degree of opening of the control valve 335 according to the rotational speed of the turbocharger 411 and the inlet temperature.

When the temperature of the oxidizing gas at the inlet of the air electrode 113 reaches a specified temperature (or when the temperature of the power generation chamber 215 reaches a specified temperature), the opening of the control valve 457 is controlled in the closing direction. Then, when the flow rate of air supplied to the start-up heater 458 decreases to reach the lower limit of use of the start-up heater 458, the start-up heater 458 is stopped. That is, after the turbocharger becomes self-sustaining, the air heated by the start-up heater 458 is supplied to the SOFC 313 until the temperature of the oxidizing gas supplied to the air electrode 113 or the temperature of the power generation chamber 215 reaches a specified temperature. temperature is performed.

In step S<b>105 , the control device 20 closes the control valve 352 to stop the supply of the fuel gas L<b>1 to the catalytic combustor 422 . The reason why the supply of the fuel gas L1 to the catalytic combustor 422 is stopped is that by starting the supply of the fuel gas L1 to the fuel electrode 109, the exhaust fuel gas is led to the catalytic combustor 422 and the rotation speed of the turbine 423 is increased. This is for suppressing the increase. As indicated by the solid line in FIG. 7, the flow rate of the fuel gas supplied to the catalytic combustor 422 changes from FL1 to 0 before time T1 at which the supply of the fuel gas L1 to the fuel electrode 109 is started.

In step S106, the control device 20 opens the blow valve 445 in response to switching the control valve 342 from the closed state to the open state and starting the supply of the fuel gas L1 to the fuel electrode 109. FIG. As shown in FIG. 8, the control device 20 controls the opening degree of the blow valve 445 from 0 to OP1 after the time T1 at which the control valve 342 is switched from the closed state to the open state.

The reason why the blow valve 445 is opened is that the supply amount of the oxidizing gas supplied to the air electrode 113 is excessive with respect to the supply amount of the fuel gas L1 supplied to the fuel electrode 109, and the startup time becomes long. This is to prevent The control device 20 adjusts the opening degree OP1 of the blow valve 445 so that the rotational speed of the turbine 423 is constant at a predetermined rotational speed.

In step S106, the controller 20 switches the blow valve 445 from the closed state to the open state after the time T1 at which the supply of the fuel gas L1 to the fuel electrode 109 is started. good. For example, after the turbocharger 411 becomes independent, the blow valve 445 may be switched from the closed state to the open state at the same time as the time T1. Also, the blow valve 445 may be switched from the closed state to the open state before time T1.

In step S107, when the temperature of the power generation chamber 215 (for example, the highest temperature among the plurality of measurement points) reaches a specified temperature, the control device 20 opens the control valve 460 to allow a small flow rate of the fuel gas L1 to flow to the air electrode 113. The temperature of the power generation chamber 215 of the SOFC 313 is further increased. At the air electrode 113 into which the air and the fuel gas L1 flowed, the catalytic action of the air electrode 113 causes the fuel gas L1 to be catalytically combusted at the air electrode 113, and the generated heat is used to raise the temperature of the power generating chamber 215.

In step S108, the control device 20 determines whether or not the power generation chamber 215 is in a predetermined preheating state, and if YES, the process proceeds to step S109. The predetermined preheating state is, for example, a state in which the temperature of the power generation chamber 215 has reached a specified temperature Te2 (for example, 700° C.; see FIG. 10) or higher.

In step S109, the control device 20 controls the blow valve 445 to switch to the closed state in response to the power generation chamber 215 reaching a predetermined preheated state. As shown in FIG. 8, the control device 20 switches the blow valve 445 to the closed state at time T2 when the power generation chamber 215 reaches a predetermined preheated state.

In step S110, the control device 20 opens the control valve 352 and restarts the supply of the fuel gas L1 to the catalytic combustor 422 in response to the generation chamber 215 reaching the predetermined preheating state. The reason why the supply of the fuel gas L1 to the catalytic combustor 422 is restarted is that the exhaust fuel gas L3 led to the catalytic combustor 422 is reduced as the power generation chamber 215 reaches a predetermined preheated state. As indicated by the solid line in FIG. 7, the flow rate of the fuel gas supplied to the catalytic combustor 422 changes from 0 to FL1 after time T2 when the power generation chamber 215 reaches a predetermined preheated state.

In step S111, the control device 20 converts the power generated by the SOFC 313 into predetermined AC power by a power conversion device (eg, inverter device), and supplies the power to the power supply destination (eg, load equipment or power system). Control to start supply. The control device 20 detects that the temperature of the generator chamber 215 (for example, the lowest temperature among the plurality of measurement points) reaches a specified temperature Te2 (for example, 700° C.) and the operating states of the fuel electrode 109 and the air electrode 113 reach predetermined conditions. After that, the power generation of the SOFC 313 is started. The temperature of the power generation chamber 215 is raised by the heat generated by both the catalytic combustion due to the addition and supply of the fuel gas L1 to the air electrode 113 and the heat generated by the power generation.

In step S112, control device 20 determines whether power generation chamber 215 is in a predetermined heating state, and if YES, proceeds to step S113. The predetermined heating state is, for example, a state in which the temperature of the power generation chamber 215 reaches or exceeds a predetermined temperature Te3 (for example, 750° C.) at which the temperature can be maintained by self-heating due to power generation. After the temperature of the power generation chamber 215 rises above a predetermined temperature, the controller 20 gradually decreases the supply amount of the fuel gas L1 added to the air electrode 113. For example, when the target load is reached, the air electrode The additional supply of the fuel gas L1 to 113 is controlled to be zero.

In step S113, the control device 20 determines whether or not the activation of the fuel cell system 310 is completed, and if YES, terminates the processing of this flowchart. When the controller 20 determines that the temperature of the power generation chamber 215 of the SOFC 313 has reached the target temperature and the load has reached the target load such as the rated load, it determines that the startup of the fuel cell system 310 has been completed. Thus, fuel cell system 310 is activated.

As described above, the fuel cell system 310 of the present embodiment opens the blow valve 445 when starting to supply the fuel gas L1 to the fuel electrode 109, whereby the oxidizing gas supplied to the air electrode 113 To prevent the supply amount of gas from becoming excessive with respect to the supply amount of the fuel gas L1 supplied to the fuel electrode 109, thereby preventing the start-up time from becoming longer.

Hereinafter, the fuel cell system 310 of this embodiment and the fuel cell system of the comparative example will be compared with each other with reference to FIGS. 7 to 12. FIG. The fuel cell system of the comparative example keeps the blow valve 445 closed when starting power generation in the power generation chamber 215 .

As shown in FIG. 7, in the present embodiment, the flow rate of the fuel gas L1 supplied to the catalytic combustor 422 changes from FL1 to 0 before the time T1 at which the supply of the fuel gas L1 to the fuel electrode 109 is started. do. On the other hand, in the comparative example, the flow rate of the fuel gas L1 supplied to the catalytic combustor 422 changes from FL1 to the minimum flow rate greater than 0 before the time T1 at which the supply of the fuel gas L1 to the fuel electrode 109 is started. The minimum flow rate is the flow rate for maintaining the ignition state of the catalytic combustor 422 .

The timing at which the supply of the fuel gas L1 to the catalytic combustor 422 is resumed is time T2 in the present embodiment, while it is after time T4, which is later than time T2, in the comparative example. Time T4 is the timing at which the power generation chamber of the fuel cell system of the comparative example reaches a predetermined heating state.

As shown in FIG. 8, in this embodiment, the opening of the blow valve 445 is controlled from 0 to OP1 after the time T1 at which the supply of the fuel gas L1 to the fuel electrode 109 is started. On the other hand, in the comparative example, the blow valve 445 is kept closed when starting to supply the fuel gas L1 to the fuel electrode 109 .

As shown in FIG. 9, in this embodiment, the supply of the fuel gas L1 to the fuel electrode 109 is started at time T1. During the period from time T1 to time T5, the flow rate of the fuel gas L1 supplied to the fuel electrode 109 is constant at FL2. After the generation chamber of the SOFC 313 reaches the target temperature at time T5, the flow rate of the fuel gas L1 supplied to the fuel electrode 109 increases or decreases according to the target load. FIG. 9 shows an example in which the target load gradually increases from time T5. In addition, in the comparative example, the flow rate of the fuel gas L1 supplied to the fuel electrode 109 is the same as that of the present embodiment.

As shown in FIG. 10, in the present embodiment, the temperature of the generator chamber 215 gradually increases from Te1 from time T1, reaches Te2 at time T2, and reaches Te3, which is the target temperature, at time T3. On the other hand, in the comparative example, the temperature of the power generation chamber 215 gradually increases from Te1 from time T1, reaches Te2 after time T2, and reaches the target temperature Te3 at time T5 later than time T3.

As is clear from FIG. 10, the startup time from time T1 until the temperature of the power generation chamber 215 reaches Te2, which is the target temperature, is longer in the fuel cell system 310 of the present embodiment than in the fuel cell system of the comparative example. short. This is because the oxidizing gas is discharged from the blow line 444 in the period from time T1 to time T4 in the present embodiment, whereas the oxidizing gas is discharged from the blow line 444 in the period from time T1 to time T4 in the comparative example. This is because it takes time to raise the temperature of the generator chamber 215 without being discharged.

As shown in FIG. 11, in the present embodiment, the rotational speed [rpm] of the turbine 423, which was r4 at time T0, decreases in response to the opening of the blow valve 445, and reaches r4 at time T1. becomes r1. After that, from time T1, the rotation speed of the turbine 423 increases to r3. After that, the rotation speed of the turbine 423 gradually decreases to r2, and increases again to a constant rotation speed after time T2 when the blow valve 445 is switched to the closed state. The reason why the rotation speed of the turbine 423 decreases from r3 to r2 is that the fuel gas L1 sufficiently reacts in the power generation chamber 215 to reduce the unburned components contained in the exhaust fuel gas L3. This is because the amount of combustion gas G to be consumed is reduced.

On the other hand, as shown in FIG. 11, in the comparative example, the rotation speed of the turbine 423 gradually increases from time T1 to time T4, and then decreases to a constant rotation speed. The reason why the rotation speed of the turbine 423 gradually increases from time T1 to time T4 is that the blow valve 445 is kept closed even after time T1.

As shown in FIG. 12, in this embodiment, the flow rate of the oxidizing gas supplied to the power generation chamber 215, which was FL6 at time T0, decreases as the blow valve 445 opens. Then, it becomes FL3 at time T1. Thereafter, from time T1, the flow rate of the oxidizing gas increases to FL5. After that, the flow rate of the oxidizing gas gradually decreases to FL4, and after time T2 when the blow valve 445 is switched to the closed state, it increases again to reach a constant rotation speed.

On the other hand, as shown in FIG. 12, in the comparative example, the flow rate of the oxidizing gas supplied to the power generation chamber 215 gradually increases from time T1 to time T4, and then decreases to a constant flow rate. The reason why the flow rate of the oxidizing gas gradually increases from time T1 to time T4 is that the closed state of blow valve 445 is maintained even after time T1.

In step S108 of the flowchart described above, it is determined that the power generation chamber 215 is in a predetermined heated state when the temperature of the power generation chamber 215 reaches or exceeds a predetermined temperature at which the temperature can be maintained by self-heating due to power generation. may be For example, as shown in FIG. 11, when the rotation speed per unit time of the turbine 423 (turbocharger 411) changes from an upward trend (change from r2 to r3) to a downward trend (change from r3 to r2), Accordingly, it may be determined that the power generation chamber 215 is in a predetermined heating state. In this case, the control device 20 switches the blow valve 445 to the closed state in response to the change in the rotation speed per unit time of the turbine 423 from an increasing tendency to a decreasing tendency.

The operation and effects of the fuel cell system 310 of this embodiment described above will be described.

According to the fuel cell system 310 of this embodiment, when the control valve 342 is switched from the closed state to the open state to start supplying the fuel gas L1 to the fuel electrode 109, the blow valve 445 is opened. Since part of the oxidizing gas A2 compressed by the compressor 421 and guided to the oxidizing gas supply line 331 is discharged to the outside from the open blow valve 445, the blow valve 445 is closed. , the supply amount of the oxidizing gas A2 supplied to the air electrode 113 through the oxidizing gas supply line 331 decreases.

Therefore, it is possible to prevent the supply amount of the oxidizing gas A2 to be supplied to the air electrode 113 from being excessive with respect to the supply amount of the fuel gas to be supplied to the fuel electrode 109, thereby prolonging the startup time. In addition, the start-up time required from the start of supply of the fuel gas L1 to the fuel electrode 109 until the generation chamber 215 reaches a predetermined heated state can be shortened.

According to the fuel cell system 310 of this embodiment, the blow valve 445 is closed in response to the generation chamber 215 of the fuel cell being heated to a predetermined state by the oxidizing gas A2 heated by the start-up heater 458. can be switched to When the blow valve 445 is closed, the flow rate of the oxidizing gas A2 supplied to the air electrode 113 increases. Therefore, the oxidizing gas A2 supplied to the air electrode 113 and the fuel gas L1 supplied to the fuel electrode 109 can be appropriately reacted.

According to the fuel cell system 310 according to the present embodiment, the oxidizing gas supplied to the air electrode 113 is closed by switching the blow valve 445 to the closed state in response to the temperature of the power generation chamber 215 becoming equal to or higher than the predetermined temperature. Increase the flow rate of A2. Since the temperature of the power generation chamber 215 is higher than the predetermined temperature and the activity of the catalyst of the fuel cell is increased, the oxidizing gas A2 supplied to the air electrode 113 and the fuel gas L1 supplied to the fuel electrode 109 are properly controlled. can be reacted.

According to the fuel cell system 310 according to this embodiment, the blow valve 445 is switched to the closed state in response to the change in the rotation speed per unit time of the turbocharger 411 from an increasing tendency to a decreasing tendency. A change from an upward trend to a downward trend indicates that the unreacted exhaust fuel gas L3 has decreased due to the increased activity of the fuel cell catalyst. By closing the blow valve 445, the flow rate of the oxidizing gas A2 supplied to the air electrode 113 is increased. can be reacted appropriately.

[Second embodiment]
A fuel cell system 310 according to a second embodiment of the present disclosure will be described below with reference to the drawings. The fuel cell system 310 of the present embodiment is a modification of the fuel cell system 310 of the first embodiment, and is assumed to be the same as that of the first embodiment unless otherwise specified below. omitted.

The fuel cell system 310 of this embodiment increases the opening of the control valve 457 prior to switching the control valve 342 from the closed state to the open state, thereby increasing the temperature of the oxidizing gas supplied to the air electrode. This increases the temperature of the power generation chamber 215 when power generation is started.

FIG. 13 is a graph showing changes in the degree of opening of the control valve (heating control valve) 457. As shown in FIG. FIG. 14 is a graph showing changes in the degree of opening of the control valve (oxidizing gas control valve) 335. As shown in FIG. FIG. 15 is a graph showing temperature changes in the power generation chamber 215. As shown in FIG. Times T0, T1, T2, T3, T4, and T5 are the same as those described in the first embodiment. Time T1 is the time when the supply of the fuel gas L1 to the fuel electrode 109 is started. Time T2 is the time at which power generation chamber 215 reaches a predetermined heating state.

As shown in FIG. 13, the control device 20 of the present embodiment increases the degree of opening of the control valve 457 from OP2 to OP3 at time T1a prior to switching the control valve 342 from the closed state to the open state. After that, the control device 20 reduces the opening degree of the control valve 457 from OP3 to OP2 at time T2 when the power generation chamber 215 reaches a predetermined heating state.

In the first embodiment, the control device 20 maintains the opening degree of the control valve 457 at OP2 after time T2. Further, the time T1a is the time prior to the transition from the operating state at a certain time after the SOFC 313 has been activated to the operating state set in advance according to the load request (for example, a change from 50% load to 100% load). good too. By controlling the opening degrees of the control valve (heating control valve) 457 and the control valve (oxidizing gas control valve) 335 to preset opening degrees according to load requirements, fluctuations in the temperature of the generator chamber 215 can be suppressed. .

For example, when the load is changed from 50% to 100%, the controller 20 presets the openings of the heating control valve 457 and the oxidizing gas control valve 335 prior to increasing the opening of the control valve 342. Further, by increasing and decreasing the respective openings so as to achieve the opening at 100% load operation, it is possible to suppress excessive rise in temperature of the generator chamber and excessive rotation of the turbocharger 411 due to an increase in load.

For example, when changing from 100% load to 50% load, the control device 20 reduces the opening degrees of the heating control valve 457 and the oxidizing gas control valve 335 in advance before reducing the opening degree of the control valve 342. It is possible to maintain the generator chamber temperature and ensure the required rotation speed of the turbocharger 411 as the load decreases by decreasing and increasing the respective opening degrees so that the set opening degree for 50% load operation is achieved. can.

As shown in FIG. 14, the control device 20 of the present embodiment reduces the degree of opening of the control valve 335 from OP5 to OP4 at time T1a prior to switching the control valve 342 from the closed state to the open state. After that, the control device 20 increases the opening degree of the control valve 335 from OP4 to OP5 at time T2 when the power generation chamber 215 reaches a predetermined heating state. In the first embodiment, the control device 20 maintains the opening degree of the control valve 335 at OP5.

The opening degree OP4 of the control valve 335 is the amount of increase in the oxidizing gas due to the increase in the opening degree of the control valve 457 from OP2 to OP3 and the amount of oxidizing gas due to the decrease in the opening degree of the control valve 335 from OP5 to OP4. is set to match the amount of decrease in That is, the opening degree OP4 of the control valve 335 is set so as to offset the increased amount of the oxidizing gas supplied from the starting air heating line 455 to the oxidizing gas supply line 331 .

As shown in FIG. 15, in the first embodiment, the temperature of the power generation chamber 215 at time T1 is Te1, and at time T3, the temperature of the power generation chamber 215 reaches the target temperature, time Te3. On the other hand, in the second embodiment, the temperature of the power generation chamber 215 at time T1 is Te1a, which is higher than Te1, and the temperature of the power generation chamber 215 reaches the target temperature at time Te3 earlier than time T3. Thus, the control device 20 of the present embodiment increases the opening degree of the control valve 457 from OP2 to OP3 and decreases the opening degree of the control valve 335 from OP5 to OP4 at time T1a. Control valve 335 .

At time T1a, the control device 20 of the present embodiment increases the opening of the control valve (heating control valve) 457 and decreases the opening of the control valve (oxidizing gas control valve) 335. A first control step for controlling the valve 335 is performed. At time T1, the control device 20 opens the control valve 342 from the closed state while the opening degree of the control valve 457 increases from OP2 to OP3 and the opening degree of the control valve 335 decreases from OP5 to OP4. Control valve 342 to switch to state. The control device 20 of the present embodiment switches the control valve 342 from the closed state to the open state in a state where the opening degree of the control valve 457 increases and the opening degree of the control valve 335 decreases at time T1. to perform a second control step of controlling the

Note that the control device 20 may reduce the opening degree of the control valve (connection control valve) 456 at time T1a prior to switching the control valve 342 from the closed state to the open state. In this case, the control device 20 increases the degree of opening of the control valve 456 and returns it to the original degree of opening at time T2. The control valve 456 is arranged in a connection line that connects the exhaust oxidizing gas line 333 and the starting air heating line 455 .

According to the fuel cell system 310 of this embodiment, the oxidizing gas supplied to the air electrode 113 is increased by increasing the opening of the control valve 457 prior to switching the control valve 342 from the closed state to the open state. The temperature of A2 can be increased. Therefore, the temperature of the power generation chamber 215 increases when the control valve 342 is switched from the closed state to the open state, compared to the case where the opening degree of the control valve 457 is not increased. As the temperature of the power generation chamber 215 rises, the activity of the catalyst of the fuel cell increases, so the amount of unreacted exhaust fuel gas L3 decreases, and the number of revolutions per unit time of the turbine 423 driven by the exhaust fuel gas L3 increases. increase can be suppressed.

Further, according to the fuel cell system 310 of the present embodiment, by decreasing the opening degree of the control valve 335, the amount of increase in the oxidizing gas supplied from the starting air heating line 455 to the oxidizing gas supply line 331 can be reduced. can be offset. Therefore, it is possible to prevent the supply amount of the oxidizing gas A2 supplied from the oxidizing gas supply line 331 to the air electrode 113 from excessively increasing, thereby preventing the start-up time from becoming longer.

The fuel cell system and the method of operating the fuel cell system described in each of the embodiments described above are grasped, for example, as follows.
A fuel cell system (310) according to a first aspect of the present disclosure includes a fuel cell (313) having an air electrode and a fuel electrode, and exhaust fuel gas and exhaust oxidizing gas discharged from the fuel cell are supplied as combustion gas. a turbocharger (411) having a turbine driven by the turbine and a compressor driven by the turbine; an oxidizing gas supply line (331) for supplying the oxidizing gas compressed by the compressor to the air electrode; A fuel gas line (341) that supplies the fuel electrode, a fuel gas control valve (342) that is arranged in the fuel gas line, and a heating unit that heats the oxidizing gas flowing through the oxidizing gas supply line ( 455, 457, 458), a blow line (444) connected to the oxidizing gas supply line and discharging the oxidizing gas to the outside, a blow valve (445) arranged in the blow line, the When the fuel gas control valve is switched from the closed state to the open state to start supplying the fuel gas to the fuel electrode, the blow valve is opened, and the power generation chamber (215) of the fuel cell is heated by the heating unit. a control device (20) for controlling the fuel gas control valve and the blow valve so as to switch the blow valve to a closed state in response to reaching a predetermined heating state by the heated oxidizing gas.

According to the fuel cell system according to the first aspect of the present disclosure, the blow valve is opened when the fuel gas control valve is switched from the closed state to the open state to start supplying the fuel gas to the fuel electrode. Since part of the oxidizing gas compressed by the compressor and led to the oxidizing gas supply line is discharged to the outside from the open blow valve, the oxidizing gas supply is more difficult than when the blow valve is closed. The amount of oxidizing gas supplied to the cathode through the line is reduced.

Therefore, it is possible to prevent the amount of the oxidizing gas supplied to the air electrode from being excessively large with respect to the amount of the fuel gas supplied to the fuel electrode, thereby prolonging the start-up time. Further, it is possible to shorten the start-up time required from the start of supply of the fuel gas to the fuel electrode until the generation chamber reaches a predetermined heated state.

According to the fuel cell system according to the first aspect of the present disclosure, the blow valve is switched to the closed state in response to the generation chamber of the fuel cell being heated to a predetermined state by the oxidizing gas heated by the heating unit. . When the blow valve is closed, the flow rate of the oxidizing gas supplied to the air electrode increases, but the power generation chamber is heated to a predetermined level and the activity of the catalyst in the fuel cell is increased. Therefore, the oxidizing gas supplied to the air electrode and the fuel gas supplied to the fuel electrode can be properly reacted.

In a fuel cell system according to a second aspect of the present disclosure, in the first aspect, the control device switches the blow valve to a closed state in response to the temperature of the power generation chamber becoming equal to or higher than a predetermined temperature.
According to the fuel cell system according to the second aspect of the present disclosure, the oxidizing gas supplied to the air electrode is reduced by switching the blow valve to the closed state in response to the temperature of the power generation chamber becoming equal to or higher than the predetermined temperature. Increase flow rate. Since the temperature of the power generation chamber reaches a predetermined temperature or higher and the activity of the fuel cell catalyst is increased, the oxidizing gas supplied to the air electrode and the fuel gas supplied to the fuel electrode can be appropriately reacted. .

In a fuel cell system according to a third aspect of the present disclosure, in the first aspect or the second aspect, the control device controls, in response to a change in the rotation speed per unit time of the turbocharger from an upward trend to a downward trend, The configuration may be such that the blow valve is switched to a closed state.

According to the fuel cell system according to the third aspect of the present disclosure, the blow valve is switched to the closed state in response to the change in the rotation speed per unit time of the turbocharger from an increasing tendency to a decreasing tendency. A change from an upward trend to a downward trend indicates that unreacted exhaust fuel gas has decreased due to increased activity of the fuel cell catalyst. By closing the blow valve, the flow rate of the oxidizing gas supplied to the air electrode is increased, but the oxidizing gas supplied to the air electrode and the fuel gas supplied to the fuel electrode must be appropriately reacted. can be done.

A fuel cell system according to a fourth aspect of the present disclosure includes a fuel cell having an air electrode and a fuel electrode, a turbine to which exhaust fuel gas and exhaust oxidizing gas discharged from the fuel cell are supplied as combustion gas, and the turbine. an oxidizing gas supply line for supplying the oxidizing gas compressed by the compressor to the air electrode; and an oxidizing gas control valve arranged in the oxidizing gas supply line. (335), a fuel gas line for supplying the fuel gas to the fuel electrode, a fuel gas control valve arranged in the fuel gas line, and a heater for heating the oxidizing gas flowing through the oxidizing gas supply line. and the heating unit includes an oxidizing gas heating line (455 ) and a heating control valve (457) arranged in the oxidizing gas heating line, and the degree of opening of the heating control valve is increased or decreased according to a preset operating state of the fuel cell. and a controller for controlling the heating control valve and the oxidizing gas control valve so as to decrease or increase the degree of opening of the oxidizing gas control valve.

According to the fuel cell system according to the fourth aspect of the present disclosure, the degree of opening of the heating control valve is increased in accordance with the preset operating state of the fuel cell, thereby reducing the amount of oxidizing gas supplied to the air electrode. Temperature can be increased. Therefore, the temperature of the power generation chamber increases when the fuel gas control valve is switched from the closed state to the open state, compared to the case where the opening degree of the heating control valve is not increased. As the temperature of the power generation chamber rises, the activity of the catalyst in the fuel cell increases, reducing the amount of unreacted exhaust fuel gas and suppressing an increase in the number of revolutions per unit time of the turbine driven by the exhaust fuel gas. be able to.

Further, according to the fuel cell system according to the fourth aspect of the present disclosure, the degree of opening of the oxidizing gas control valve is reduced in accordance with the preset operating state of the fuel cell, so that the oxidizing gas heating line An increased amount of oxidizing gas supplied to the oxidizing gas supply line can be offset. Therefore, it is possible to prevent an excessive increase in the supply amount of the oxidizing gas supplied from the oxidizing gas supply line to the air electrode, thereby preventing an increase in the start-up time.

A fuel cell system according to a fifth aspect of the present disclosure, in the fourth aspect, is characterized by: a blow line connected to the oxidizing gas supply line and discharging the oxidizing gas to the outside; a valve, wherein the control device opens the blow valve when switching the fuel gas control valve from a closed state to an open state to start supplying the fuel gas to the fuel electrode; controlling the fuel gas control valve and the blow valve so as to switch the blow valve to a closed state in response to the generation chamber of the fuel cell being heated to a predetermined state by the oxidizing gas heated by the heating unit; .

According to the fuel cell system according to the fifth aspect of the present disclosure, the blow valve is opened when the fuel gas control valve is switched from the closed state to the open state to start supplying the fuel gas to the fuel electrode. Since part of the oxidizing gas compressed by the compressor and led to the oxidizing gas supply line is discharged to the outside from the open blow valve, the oxidizing gas supply is more difficult than when the blow valve is closed. The amount of oxidizing gas supplied to the cathode through the line is reduced.

Therefore, it is possible to prevent the amount of the oxidizing gas supplied to the air electrode from being excessively large with respect to the amount of the fuel gas supplied to the fuel electrode, thereby prolonging the start-up time. Further, it is possible to shorten the start-up time required from the start of supply of the fuel gas to the fuel electrode until the generation chamber reaches a predetermined heated state.

According to the fuel cell system according to the fifth aspect of the present disclosure, the blow valve is switched to the closed state in response to the generation chamber of the fuel cell reaching a predetermined heating state due to the oxidizing gas heated by the heating unit. . When the blow valve is closed, the flow rate of the oxidizing gas supplied to the air electrode increases, but the power generation chamber is heated to a predetermined level and the activity of the catalyst in the fuel cell is increased. Therefore, the oxidizing gas supplied to the air electrode and the fuel gas supplied to the fuel electrode can be properly reacted.

A fuel cell system according to a sixth aspect of the present disclosure, in the fifth aspect, is characterized by a combustor (422) for burning the exhaust fuel gas discharged from the fuel cell, and the exhaust oxidizer discharged from the fuel cell. An exhaust oxidizing gas line (333) for supplying gas to the combustor, and a connection control valve (456) arranged in a connection line connecting the exhaust oxidizing gas line and the oxidizing gas heating line, The control device controls the connection control valve so as to decrease the degree of opening of the connection control valve prior to switching the fuel gas control valve from the closed state to the open state.

According to the fuel cell system according to the sixth aspect of the present disclosure, prior to switching the fuel gas control valve from the closed state to the open state, by reducing the opening degree of the connection control valve, By increasing the flow rate of the oxidizing gas supplied to the oxidizing gas supply line, the temperature of the oxidizing gas supplied to the air electrode can be increased.

A method of operating a fuel cell system according to a seventh aspect of the present disclosure is characterized in that the fuel cell system comprises a fuel cell having an air electrode and a fuel electrode, and exhaust fuel gas and exhaust oxidizing gas discharged from the fuel cell are combusted. a turbocharger having a turbine supplied as gas and a compressor driven by said turbine; an oxidizing gas supply line for supplying oxidizing gas compressed by said compressor to said air electrode; a fuel gas control valve arranged in the fuel gas line; a heating unit for heating the oxidizing gas flowing through the oxidizing gas supply line; and a heating unit connected to the oxidizing gas supply line. and a blow valve disposed in the blow line, wherein the fuel gas control valve is switched from a closed state to an open state to switch the fuel gas control valve to the fuel electrode. a step of starting the supply of fuel gas; and a step of opening the blow valve when switching the fuel gas control valve from a closed state to an open state to start supplying the fuel gas to the fuel electrode; A control step of controlling the blow valve to switch the blow valve to a closed state in response to the generation chamber of the fuel cell reaching a predetermined heated state by the oxidizing gas heated by the heating unit.

According to the fuel cell system operating method according to the seventh aspect of the present disclosure, when the fuel gas control valve is switched from the closed state to the open state to start supplying the fuel gas to the fuel electrode, the blow valve is opened. becomes. Since part of the oxidizing gas compressed by the compressor and led to the oxidizing gas supply line is discharged to the outside from the open blow valve, the oxidizing gas supply is more difficult than when the blow valve is closed. The amount of oxidizing gas supplied to the cathode through the line is reduced.

Therefore, it is possible to prevent the amount of the oxidizing gas supplied to the air electrode from being excessively large with respect to the amount of the fuel gas supplied to the fuel electrode, thereby prolonging the start-up time. Further, it is possible to shorten the start-up time required from the start of supply of the fuel gas to the fuel electrode until the generation chamber reaches a predetermined heated state.

According to the method of operating a fuel cell system according to the seventh aspect of the present disclosure, the blow valve is closed in response to the generation chamber of the fuel cell being heated to a predetermined state by the oxidizing gas heated by the heating unit. can be switched to When the blow valve is closed, the flow rate of the oxidizing gas supplied to the air electrode increases, but the power generation chamber is heated to a predetermined level and the activity of the catalyst in the fuel cell is increased. Therefore, the oxidizing gas supplied to the air electrode and the fuel gas supplied to the fuel electrode can be properly reacted.

In the method of operating a fuel cell system according to the eighth aspect of the present disclosure, the fuel cell system includes a fuel cell having an air electrode and a fuel electrode, and exhaust fuel gas and exhaust oxidizing gas discharged from the fuel cell as combustion gas. and a compressor driven by the turbine, an oxidizing gas supply line for supplying the oxidizing gas compressed by the compressor to the air electrode, and the oxidizing gas supply line. an oxidizing gas control valve arranged; a fuel gas line for supplying fuel gas to the fuel electrode; a fuel gas control valve arranged in the fuel gas line; a heating unit for heating the gas, the heating unit having one end connected to the upstream side of the oxidizing gas control valve and the other end connected to the downstream side of the oxidizing gas control valve; A gas heating line and a heating control valve arranged in the oxidizing gas heating line are provided, and the degree of opening of the heating control valve is increased or decreased according to a preset operating state of the fuel cell. and controlling the heating control valve and the oxidizing gas control valve so as to decrease or increase the degree of opening of the oxidizing gas control valve.

According to the fuel cell system operating method according to the eighth aspect of the present disclosure, the degree of opening of the heating control valve is increased in accordance with the preset operating state of the fuel cell, thereby increasing the amount of oxidation gas supplied to the air electrode. the temperature of the gas can be increased. Therefore, the temperature of the power generation chamber increases when the fuel gas control valve is switched from the closed state to the open state, compared to the case where the opening degree of the heating control valve is not increased. As the temperature of the power generation chamber rises, the activity of the catalyst in the fuel cell increases, reducing the amount of unreacted exhaust fuel gas and suppressing an increase in the number of revolutions per unit time of the turbine driven by the exhaust fuel gas. be able to.

Further, according to the method of operating a fuel cell system according to the eighth aspect of the present disclosure, the degree of opening of the oxidizing gas control valve is reduced according to the preset operating state of the fuel cell, thereby reducing the amount of oxidizing gas. An increased amount of oxidizing gas supplied from the heating line to the oxidizing gas supply line can be offset. Therefore, it is possible to prevent an excessive increase in the supply amount of the oxidizing gas supplied from the oxidizing gas supply line to the air electrode, thereby preventing an increase in the start-up time.

In the method for operating a fuel cell system according to the ninth aspect of the present disclosure, the fuel cell system includes a fuel cell having an air electrode and a fuel electrode, and exhaust fuel gas and exhaust oxidizing gas discharged from the fuel cell are combusted. A turbocharger having a turbine supplied as gas and a compressor driven by the turbine, an oxidizing gas supply line for supplying the oxidizing gas compressed by the compressor to the air electrode, and the oxidizing gas supply line. a fuel gas line that supplies fuel gas to the fuel electrode; a fuel gas control valve that is disposed in the fuel gas line; and the oxidizing gas flowing through the oxidizing gas supply line. a heating unit for heating the oxidizing gas, wherein the heating unit has one end connected to the upstream side of the oxidizing gas control valve and the other end connected to the downstream side of the oxidizing gas control valve. and a heating control valve arranged in the oxidizing gas heating line, wherein the opening of the heating control valve is increased and the opening of the oxidizing gas control valve is decreased. a first control step of controlling a heating control valve and said oxidizing gas control valve; and a second control step of controlling the fuel gas control valve to switch the valve from a closed state to an open state.

According to the method of operating a fuel cell system according to the ninth aspect of the present disclosure, prior to switching the fuel gas control valve from the closed state to the open state, by increasing the opening degree of the heating control valve, The temperature of the supplied oxidizing gas can be increased. Therefore, the temperature of the power generation chamber increases when the fuel gas control valve is switched from the closed state to the open state, compared to the case where the opening degree of the heating control valve is not increased. As the temperature of the power generation chamber rises, the activity of the catalyst in the fuel cell increases, reducing the amount of unreacted exhaust fuel gas and suppressing an increase in the number of revolutions per unit time of the turbine driven by the exhaust fuel gas. be able to.

Further, according to the method of operating a fuel cell system according to the ninth aspect of the present disclosure, by reducing the opening degree of the oxidizing gas control valve, the oxidizing gas supplied from the oxidizing gas heating line to the oxidizing gas supply line is It is possible to offset the increase in oxidizing gas due to the oxidizing gas. Therefore, it is possible to prevent an excessive increase in the supply amount of the oxidizing gas supplied from the oxidizing gas supply line to the air electrode, thereby preventing an increase in the start-up time.

20 Control device 109 Fuel electrode 113 Air electrode 215 Power generation chamber 310 Fuel cell system 329 Combustion exhaust gas line 331 Oxidizing gas supply line 333 Exhaust oxidizing gas line 335 Control valve (oxidizing gas control valve)
341 fuel gas line 342 control valve (fuel gas control valve)
343 Exhaust fuel gas line 346 Shutoff valve 347 Regulating valve 348 Recirculation blower 349 Fuel gas recirculation line 350 Exhaust fuel gas release line 351 Exhaust air cooler 411 Turbocharger 421 Compressor 422 Catalytic combustor 423 Turbine 424 Rotating shaft 430 Heat exchange Vessel 441 Orifice 442 Exhaust heat recovery device 443 Control valve 444 Oxidizing gas blow line 445 Blow valve 451 Control valve 452 Blower 455 Start air heating line (oxidizing gas heating line)
456 control valve 457 control valve (heating control valve)
458 Startup heater 459 Control valve 460 Control valve A Air A2 Oxidizing gas A3 Exhaust oxidizing gas G Combustion gas L1 Fuel gas L3 Exhaust fuel gas T0, T1, T1a, T2, T3, T4, T5 Time

Claims (6)

a fuel cell having an air electrode and an anode;
a turbocharger having a turbine to which exhaust fuel gas and exhaust oxidizing gas discharged from the fuel cell are supplied as combustion gas, and a compressor driven by the turbine;
an oxidizing gas supply line for supplying the oxidizing gas compressed by the compressor to the air electrode;
a fuel gas line for supplying fuel gas to the fuel electrode;
a fuel gas control valve arranged in the fuel gas line;
a heating unit that heats the oxidizing gas flowing through the oxidizing gas supply line;
a blow line connected to the oxidizing gas supply line and discharging the oxidizing gas to the outside;
a blow valve disposed in the blow line;
When the fuel gas control valve is switched from the closed state to the open state to start supplying the fuel gas to the fuel electrode, the blow valve is opened, and the power generation chamber of the fuel cell is heated by the heating unit. and a controller for controlling the fuel gas control valve and the blow valve so as to switch the blow valve to a closed state in response to a predetermined heating state due to the oxidizing gas. 2. The fuel cell system according to claim 1, wherein the control device switches the blow valve to a closed state when the temperature of the power generation chamber reaches or exceeds a predetermined temperature. 3. The fuel cell system according to claim 1, wherein the control device switches the blow valve to a closed state in response to a change in the rotation speed per unit time of the turbocharger from an increasing tendency to a decreasing tendency. a fuel cell having an air electrode and an anode;
a turbocharger having a turbine to which exhaust fuel gas and exhaust oxidizing gas discharged from the fuel cell are supplied as combustion gas, and a compressor driven by the turbine;
an oxidizing gas supply line for supplying the oxidizing gas compressed by the compressor to the air electrode;
an oxidizing gas control valve arranged in the oxidizing gas supply line;
a fuel gas line for supplying fuel gas to the fuel electrode;
a fuel gas control valve arranged in the fuel gas line;
a heating unit that heats the oxidizing gas flowing through the oxidizing gas supply line,
The heating unit
an oxidizing gas heating line having one end connected to the upstream side of the oxidizing gas control valve and the other end connected to the downstream side of the oxidizing gas control valve;
a heating control valve disposed in the oxidizing gas heating line;
The heating control valve and the oxidizing gas are controlled so as to increase or decrease the degree of opening of the heating control valve and decrease or increase the degree of opening of the oxidizing gas control valve according to a preset operating state of the fuel cell. a controller that controls the gas control valve;
a blow line connected to the oxidizing gas supply line and discharging the oxidizing gas to the outside;
a blow valve disposed in the blow line,
The control device switches the fuel gas control valve from a closed state to an open state to open the blow valve when starting to supply the fuel gas to the fuel electrode, and the power generation chamber of the fuel cell is opened. A fuel cell system for controlling the fuel gas control valve and the blow valve so as to switch the blow valve to a closed state in response to a predetermined heating state by the oxidizing gas heated by the heating unit. a combustor for burning the exhaust fuel gas discharged from the fuel cell;
an exhaust oxidizing gas line for supplying the exhaust oxidizing gas discharged from the fuel cell to the combustor;
A connection control valve arranged in a connection line connecting the exhaust oxidizing gas line and the oxidizing gas heating line,
5. The fuel cell system according to claim 4 , wherein the control device controls the connection control valve so as to decrease the degree of opening of the connection control valve prior to switching the fuel gas control valve from the closed state to the open state. . A method of operating a fuel cell system, comprising:
The fuel cell system is
a fuel cell having an air electrode and an anode;
a turbocharger having a turbine to which exhaust fuel gas and exhaust oxidizing gas discharged from the fuel cell are supplied as combustion gas, and a compressor driven by the turbine;
an oxidizing gas supply line for supplying the oxidizing gas compressed by the compressor to the air electrode;
a fuel gas line for supplying fuel gas to the fuel electrode;
a fuel gas control valve arranged in the fuel gas line;
a heating unit that heats the oxidizing gas flowing through the oxidizing gas supply line;
a blow line connected to the oxidizing gas supply line and discharging the oxidizing gas to the outside;
a blow valve disposed in the blow line,
switching the fuel gas control valve from a closed state to an open state to start supplying the fuel gas to the fuel electrode;
a step of opening the blow valve when switching the fuel gas control valve from a closed state to an open state to start supplying the fuel gas to the fuel electrode;
a control step of controlling the blow valve so as to switch the blow valve to a closed state in response to the generation chamber of the fuel cell being brought into a predetermined heated state by the oxidizing gas heated by the heating unit. How to operate a battery system.

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