JP2014137976A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an increase in facility cost in a fuel cell system including a fuel cell.SOLUTION: There is provided a fuel cell system 7 including: a cell stack 101 having cells that generate power through a reaction between hydrogen and oxygen-containing oxidant gas O1 and including a catalyst having a reforming ability of producing hydrogen from hydrocarbon and steam; a steam supply means 30 supplying steam to the cell stack 101 during power generation stops; and a vaporizer 31 heating water with heat generated by the cell stack 101 to produce steam.

Description

  The present invention relates to a fuel cell system.

  Fuel cells are expected to be used in various fields in recent years because of their low pollution and high power generation efficiency. As a fuel cell system using a fuel cell, an operation system of a single fuel cell and a combined power generation system in which a fuel cell and a gas turbine are linked are known.

  The fuel cell has a configuration in which a cartridge that generates power from a fuel gas and an oxidizing gas such as air is housed in a pressure vessel. The cartridge is composed of a bundle of cell stacks that are fuel cell assemblies.

By the way, in the fuel cell system, the cell stack is prevented from being damaged when power generation in the fuel cell module is stopped due to disconnection of the electrical connection with the power load system. The reducing gas is supplied to the fuel electrode side. That is, at the time of stoppage, the cell stack is protected by supplying reducing gas to the fuel electrode side of the cell stack.
Therefore, in Patent Document 2, a vaporizer, a reformer, and a burner for heating them are provided, and hydrogen generated by the reformer is supplied to the fuel electrode side of the cell stack even when stopped. A technique for protecting the image is disclosed.

JP 2010-80192 A

  By the way, in the above conventional system, in order to generate hydrogen, a reformer, a vaporizer, and a heating burner are provided, which is a fuel cell system utilizing internal reforming and reforming into a power generation system. The conventional system cannot be applied if it does not have a vessel. In addition, in a fuel cell system using internal reforming, a hydrogen supply facility such as a reformer can be attached, but this is not preferable in terms of facility cost and merchantability.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to ensure the protection of the cell stack in the stop operation of the fuel cell, and to provide the equipment in the fuel cell system using internal reforming. The object is to provide a fuel cell system capable of reducing costs.

In order to achieve the above object, the present invention provides the following means.
That is, the fuel cell system of the present invention has a cell that generates power by a reaction between an oxidant gas containing oxygen and hydrogen, and a cell stack that includes a catalyst having a reforming ability to generate hydrogen from hydrocarbon and steam. And a water vapor supply means for supplying water vapor to the cell stack when stopped, and a vaporizer for generating water vapor by heating water with heat generated by the cell stack.

According to the above configuration, at the time of stoppage, water is heated by sensible heat of the cell stack, and steam is supplied to the cell stack to the fuel electrode side, thereby generating hydrogen by reforming using the catalytic function of the cell stack. This eliminates the need for a reformer that generates hydrogen from water vapor and a facility for holding hydrogen such as a hydrogen cylinder, thereby suppressing an increase in facility cost.
Moreover, since water vapor | steam supplied to a cell stack is generated by heating water with the heat | fever which a cell stack emits, it becomes possible to generate water vapor | steam also at the time of a power failure.

  In the fuel cell system, the fuel cell system includes a pressure vessel in which the cell stack is accommodated, and the water vapor supply means is provided outside the pressure vessel and the vaporizer provided inside the pressure vessel. It is preferable to have a pipe for connecting the provided water supply source and the vaporizer.

  According to the above configuration, the vaporizer is disposed inside the pressure vessel and around the cell stack, whereby the heat generated by the cell stack is transmitted by the vaporizer, and the efficiency of water vapor generation can be improved.

  In the fuel cell system, it is preferable that the water vapor supply means includes a valve provided in the pipe and opened when stopped.

  The fuel cell system preferably includes a pressure accumulator in which gas is sealed in a compressed state and pressurizes water supplied from the water supply source.

  According to the present invention, in a stop operation including a trip of a power generation system using internal reforming, water vapor is supplied to the fuel electrode side of the cell stack, and hydrogen is generated from the fuel gas and water vapor by the catalytic action of the fuel electrode. As a result, it is possible to secure a reducing atmosphere on the fuel electrode side, so facilities for holding hydrogen supply facilities such as reformers and hydrogen cylinders are not required, and equipment costs are reduced by using heat from the power generation chamber. A fuel cell system can be provided.

1 is a system diagram of a combined power generation system including a fuel cell system according to an embodiment of the present invention. It is a perspective view explaining the structure of the vaporizer | carburetor which concerns on embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell module which concerns on embodiment of this invention. It is principal part sectional drawing of the cell stack which concerns on embodiment of this invention. It is sectional drawing of the cartridge which concerns on embodiment of this invention. It is a perspective view of the cartridge which concerns on embodiment of this invention. It is a graph which shows the power generation chamber temperature after trip generation | occurrence | production of the fuel cell system which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the combined power generation system 1 of this embodiment is a power generation system in which a fuel cell system 7 including a fuel cell module 2 and a gas turbine 3 are combined.
The gas turbine 3 mainly includes an air compressor 4 that sucks and compresses outside air, a combustor 5 provided on the downstream side of the air compressor 4, and a turbine 6 provided on the downstream side of the combustor 5. It has as a component. Furthermore, a generator 8 is connected to the gas turbine 3.

The combustor 5 injects fuel gas into the air to generate high-temperature combustion gas. The combustor 5 of the present embodiment includes a waste oxidant gas O2 supplied from a later-described exhaust oxidant gas pipe 340, a waste fuel gas F2 supplied from the exhaust fuel pipe 320, and a second fuel supply source 21. The supplied fuel gas is supplied.
The turbine 6 receives the supply of the high-temperature combustion gas generated by the combustor 5 to generate a rotational driving force, rotationally drives the compressor 4, and drives the generator 8. The turbine 6 is provided with a gas turbine exhaust gas duct 9 into which high-temperature combustion gas after rotating the turbine 6, that is, exhaust gas is introduced. The gas turbine exhaust gas duct 9 is a pipe that guides the exhaust gas to the outside.

The fuel cell system 7 includes the fuel cell module 2 and a water vapor supply device 30 that supplies water vapor to the fuel pipe 310 of the fuel cell module 2 when the fuel cell module 2 is stopped. Here, the stop means stopping the electrochemical reaction in the cell stack 101 and stopping the power generation by the fuel cell module.
The fuel cell module 2 includes a pressure vessel 10 and a plurality of cartridges 201 housed in the pressure vessel 10. The cartridge 201 is configured by bundling a plurality of cell stacks 101, and generates power by receiving supply of the fuel gas F1 and the oxidant gas O1. Details of the cell stack 101 will be described later.

  An oxidant gas pipe 330 that supplies the oxidant gas O1 from the gas turbine 3 and a fuel pipe 310 that supplies the fuel gas F1 from the fuel supply source 20 are connected to the cartridge 201. The fuel pipe 310 is provided with a flow rate adjustment valve 22 that adjusts the flow rate of the fuel gas F <b> 1 supplied to the cartridge 201 via the fuel pipe 310.

  In the combined power generation system 1 of the present embodiment, the fuel supply source 20 is configured to supply fuel gas only to the cartridge 201, but in addition to the cartridge 201 from the fuel supply source 20, fuel is supplied to the combustor 5. It is good also as a structure which supplies gas. That is, the second fuel supply source 21 described above may be eliminated and the fuel supply source 20 and the combustor 5 may be connected.

  Examples of the fuel gas F1 include hydrocarbon gases such as hydrogen, carbon monoxide, and methane, gases obtained by gasification of carbonaceous raw materials such as coal, and gases containing two or more of these components. Used. Further, as the oxidant gas O1, for example, a gas containing 15 to 30 vol% oxygen is used. The representative oxidant gas O1 is air, but a mixed gas of exhaust combustion gas and air or a mixed gas of oxygen and air may be used.

  Further, in the combined power generation system 1, the exhaust oxidant gas O 2 after being used for power generation in the cartridge 201 is discharged from the cartridge 201 and the exhaust oxidant gas pipe 340 that supplies the combustor 5 of the gas turbine 3. An exhaust fuel pipe 320 that supplies fuel gas (exhaust fuel gas F2) to the combustor 5 is provided. The exhaust fuel gas F <b> 2 is a fuel gas after being used for power generation in the fuel cell module 2.

The oxidant gas pipe 330 is a pipe that guides the oxidant gas compressed in the air compressor 4 of the gas turbine 3 to the cartridge 201.
A fuel recirculation pipe 325 that recirculates a part of the exhaust fuel gas F2 to the fuel pipe 310 is connected to the exhaust fuel pipe 320. That is, one end of the fuel recirculation pipe 325 is connected to the exhaust fuel pipe 320 and the other end is connected to the fuel pipe 310. The fuel recirculation pipe 325 is provided with a fuel recirculation blower 15 for supplying the exhaust fuel gas F2 flowing through the fuel recirculation pipe 325 to the fuel pipe 310.

  The combined power generation system 1 including the fuel cell system 7 of this embodiment includes a water vapor supply device 30 (water vapor supply means) that supplies water vapor to the cell stack 101 of the fuel cell module 2.

  The water vapor supply device 30 includes a vaporizer 31 arranged inside the pressure vessel 10, a water supply source 32 arranged outside the pressure vessel 10, and a first pipe connecting the vaporizer 31 and the water supply source 32. 33, and a second pipe 34 that connects the vaporizer 31 and the fuel pipe 310. The water supply source 32 has a pressure accumulator 38, and water is supplied to the first pipe 33 by the pressure of the pressure accumulator 38. Gas is sealed in the pressure accumulator 38 in a compressed state, and water can be pressurized.

  The first pipe 33 is provided with a valve 39. The valve 39 is configured to be opened when the system is stopped. That is, when the system is stopped, the valve 39 is opened, and pressurized water flows into the first pipe 33.

  The vaporizer 31 is disposed inside the pressure vessel 10 and in the vicinity of the cartridge 201 constituting the cell stack 101. That is, the heat generating chamber is disposed at a position where the heat generated by the cartridge 201 is sufficiently transmitted to the vaporizer 31 when the high temperature fuel cell having a temperature of 700 ° C. or higher is stopped.

  As shown in FIG. 2, the vaporizer 31 includes, for example, a vaporizer body 35 that is a rectangular plate member made of metal such as SUS, and a serpentine hole formed so as to meander inside the vaporizer body 35. 36. Both ends of the meandering hole 36 are opened at the end face of the vaporizer body 35, the first pipe 33 is connected to one end of the meandering hole 36, and the second pipe 34 is connected to the other end of the meandering hole 36. Has been. Note that the shape of the vaporizer body 35 is not limited to a rectangular shape, and can be changed as appropriate depending on the shape of the arrangement location.

In addition, the combined power generation system 1 of this embodiment includes a nitrogen generation source 81 that supplies nitrogen (N 2) to the fuel pipe 310. The nitrogen generation source 81 is connected to the fuel pipe 310 via a pipe. As the nitrogen generation source 81, for example, a nitrogen cylinder can be adopted.
Further, an air branch pipe 18 that branches the oxidant gas O1 to the exhaust oxidant gas pipe 340 is provided from the oxidant gas pipe 330.

Next, the detailed structure of the fuel cell module 2 will be described.
As shown in FIG. 3, the fuel cell module 2 includes a cylindrical pressure vessel 10 that extends in the vessel central axis direction Dv around the vessel central axis Av, and a plurality of cartridges 201 arranged in the pressure vessel 10. Have.

  The pressure vessel 10 is operated, for example, at an internal pressure of 0.1 MPa to about 5 MPa and an internal temperature of atmospheric temperature to about 550 ° C. For this reason, in consideration of pressure resistance, the pressure vessel 10 has a cylindrical body 11 and hemispherical mirrors 12 formed at both ends in the central axis direction of the body 11. Yes. The pressure vessel 10 has a cylindrical shape as a whole, and is installed such that the vessel central axis Av extends in the vertical direction. Further, the pressure vessel 10 is formed of a stainless steel material such as SUS304 because it is required to have a pressure resistance and a corrosion resistance against an oxidant such as oxygen contained in the oxidant gas O1.

  The cartridge 201 is composed of a bundle of a plurality of cell stacks. As shown in FIG. 4, the cell stack 101 as a cell assembly includes a cylindrical (or tube-shaped) base tube 103 and a plurality of fuel cells 105 formed on the outer peripheral surface of the base tube 103. And an interconnector 107 formed between the matching fuel cells 105. The fuel cell 105 is formed by stacking a fuel electrode 112, a solid electrolyte 111, and an air electrode 113. The cell stack 101 further includes an air electrode 113 of the fuel cell 105 formed at the 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. The lead film 115 is electrically connected through the interconnector 107.

  In the present embodiment, the fuel gas F1 passes through the inner peripheral side of the cylindrical (or tube-shaped) cell stack 101, and the oxidant gas O1 passes through the outer peripheral side.

The base tube 103 is a porous body formed of, for example, any one of CaO stabilized ZrO ₂ (CSZ), Y ₂ O ₃ stabilized ZrO ₂ (YSZ), MgAl ₂ O _{4, and the} like. The base tube 103 plays a role of supporting the fuel cell 105, the interconnector 107, and the lead film 115. Further, the base tube 103 also has a function of diffusing the fuel gas F1 supplied to the inner peripheral side to the fuel cells 105 formed on the outer peripheral surface of the base tube 103 through the pores of the base tube 103. .

The fuel electrode 112 is made of, for example, an oxide of a composite material of Ni and zirconia-based electrolyte material such as Ni / YSZ. In this case, in the fuel electrode 112, Ni which is a component of the fuel electrode 112 acts as a catalyst for the fuel gas F1. For example, when the fuel gas F1 supplied through the base tube 103 contains methane (CH ₄ ) and water vapor, the catalyst acts as a hydrogen (H ₂ ). And carbon monoxide (CO).

The air electrode 113 is made of, for example, a LaSrMnO ₃ oxide or a LaCoO ₃ oxide. The air electrode 113 generates oxygen ions (O ²⁻ ) by dissociating oxygen in the supplied oxidant gas O 1 in the vicinity of the interface with the solid electrolyte 111.

The solid electrolyte 111 is mainly made of YSZ, for example. This YSZ has gas tightness that prevents gas from passing through and high oxygen ion conductivity at high temperatures. The solid electrolyte 111 moves oxygen ions (O ²⁻ ) generated at the air electrode 113 to the fuel electrode 112.

In the fuel electrode 112 described above, in the vicinity of the interface with the solid electrolyte 111, hydrogen (H ₂ ) and carbon monoxide (CO) obtained by reforming, and oxygen ions (O ²⁻ ) supplied from the solid electrolyte 111. React with each other to produce water (H ₂ O) and carbon dioxide (CO ₂ ). In the fuel cell 105, electrons are released from oxygen ions during this reaction process, and electric power is generated.

The interconnector 107 is made of, for example, a conductive perovskite oxide represented by M1-xLxTiO ₃ such as SrTiO ₃ (M is an alkaline earth metal element and L is a lanthanoid element). The interconnector 107 is a dense film so that the fuel gas F1 and the oxidant gas O1 are not mixed, and has stable electrical conductivity in both an oxidizing atmosphere and a reducing atmosphere. The interconnector 107 electrically connects the air electrode 113 of one fuel cell 105 and the fuel electrode 112 of the other fuel cell 105 in adjacent fuel cells 105. That is, the interconnector 107 electrically connects adjacent fuel cells 105 in series.

  Since the lead film 115 needs to have electronic conductivity and a thermal expansion coefficient close to that of other materials constituting the cell stack 101, for example, Ni such as Ni / YSZ and a zirconia-based electrolyte material And a composite material. The lead film 115 plays a role of leading the direct-current power generated by the plurality of fuel cells 105 electrically connected in series by the interconnector 107 to the vicinity of the end portion of the cell stack 101.

  As shown in FIGS. 5 and 6, the cartridge 201 includes a plurality of cell stacks 101, a first cartridge header 220 a that covers one end of a bundle of the plurality of cell stacks 101, and a bundle of the plurality of cell stacks 101. And a second cartridge header 220b covering the other end. The plurality of cell stacks 101 are parallel to each other and aligned in the longitudinal direction thereof, and form a cylindrical shape as a whole. The first cartridge header 220a and the second cartridge header 220b have a cylindrical shape having an outer diameter slightly larger than the outer diameter of the bundle of the plurality of cell stacks 101 having a columnar shape. Therefore, the cartridge 201 as a whole has a cylindrical shape that is long in the longitudinal direction of the cell stack 101.

  Each of the first cartridge header 220a and the second cartridge header 220b includes cylindrical casings 229a and 229b in which end portions of a bundle of the plurality of cell stacks 101 enter the inside from the opening 228, and openings 228 of the casings 229a and 229b. The heat insulating bodies 227a and 227b to be closed and the tube plates 225a and 225b that partition the internal space of the casings 229a and 229b into two spaces in the longitudinal direction of the cell stack 101 are provided. The tube plates 225a, 225b and the like are formed of a metal material having high temperature durability such as Inconel (registered trademark of Special Metals Co., Ltd. for nickel-based alloys). The tube plates 225a and 225b and the heat insulators 227a and 227b are formed with through holes through which the end portions of the plurality of cell stacks 101 can be inserted. The tube plates 225a and 225b support the end portion of the cell stack 101 inserted through the through holes via a seal member or an adhesive 237. Therefore, though the tube plates 225a and 225b are formed with through holes, the air tightness of the other space with respect to one space in the casings 229a and 229b is ensured with reference to the tube plates 225a and 225b. Yes. The inner diameters of the through holes of the heat insulators 227a and 227b are formed larger than the outer diameter of the cell stack 101 inserted therethrough. That is, gaps 235a and 235b exist between the inner peripheral surfaces of the through holes of the heat insulators 227a and 227b and the outer peripheral surface of the cell stack 101 inserted through the through holes.

  A space formed by the casing 229a and the tube plate 225a of the first cartridge header 220a forms a fuel gas supply chamber 217 to which the fuel gas F1 is supplied. A fuel gas supply hole 231a for guiding the fuel gas F1 from the fuel pipe 310 to the fuel gas supply chamber 217 is formed in the casing 229a. In the fuel gas supply chamber 217, the ends of the base tube 103 in the plurality of cell stacks 101 are located and open here. The fuel gas F 1 guided from the fuel pipe 310 to the fuel gas supply chamber 217 flows into the base tube 103 of the plurality of cell stacks 101. At this time, the fuel gas F <b> 1 is distributed at a substantially uniform flow rate to the base tube 103 of the plurality of cell stacks 101 by the fuel gas supply chamber 217. For this reason, each power generation amount in the plurality of cell stacks 101 can be made uniform.

  A space formed by the casing 229b and the tube plate 225b of the second cartridge header 220b forms a fuel gas discharge chamber 219 into which the fuel gas F1 that has passed through the base tube 103 of the cell stack 101 flows. The casing 229b has a fuel gas discharge hole 231b for guiding the exhaust fuel gas F2 flowing into the fuel gas discharge chamber 219 to the exhaust fuel pipe 320. In the fuel gas discharge chamber 219, the ends of the base tube 103 in the plurality of cell stacks 101 are located and open here. As described above, the fuel gas F1 that has passed through the base tube 103 of the plurality of cell stacks 101 flows into the fuel gas discharge chamber 219, and then is discharged out of the pressure vessel 10 through the exhaust fuel pipe 320. .

  A space formed by the casing 229b, the heat insulator 227b, and the tube plate 225b of the second cartridge header 220b forms an oxidant gas supply chamber 216. An oxidant gas supply hole 233b for guiding the oxidant gas O1 from the oxidant gas pipe 330 to the oxidant gas supply chamber 216 is formed in the casing 229b. The oxidant gas O1 introduced into the oxidant gas supply chamber 216 is a gap 235b between the inner peripheral surface of the through hole of the heat insulator 227b and the outer peripheral surface of the cell stack 101 inserted through the through hole. From the first cartridge header 220a and the second cartridge header 220b.

  In the power generation chamber 215 between the first cartridge header 220a and the second cartridge header 220b, the fuel cells 105 of the plurality of cell stacks 101 are arranged. For this reason, in this power generation chamber 215, the fuel gas F1 and the oxidant gas O1 react electrochemically to generate power. In this power generation chamber 215, the temperature near the center in the longitudinal direction of the cell stack 101 becomes a high temperature atmosphere of about 700 ° C. to 1100 ° C. during steady operation of the fuel cell module 2. Further, the power generation chamber 215 is a space between the first cartridge header 220a and the second cartridge header 220b and whose outer peripheral side is surrounded by an inner heat insulating material 16 described later.

  A space formed by the casing 229a, the heat insulator 227a, and the tube plate 225a of the first cartridge header 220a forms an air discharge chamber 218 into which the exhaust oxidant gas O2 that has passed through the power generation chamber 215 flows. The casing 229a has an air discharge hole 233a for guiding the exhaust oxidant gas O2 flowing into the air discharge chamber 218 to the exhaust oxidant gas pipe 340. The oxidant gas O1 in the power generation chamber 215 enters the air discharge chamber 218 from the gap 235a between the inner peripheral surface of the through hole of the heat insulator 227a and the outer peripheral surface of the cell stack 101 inserted through the through hole. After flowing in, the exhaust gas passes through the exhaust oxidant gas pipe 340 and is discharged out of the pressure vessel 10 as the exhaust oxidant gas O2.

  As the temperature of the power generation chamber 215 increases, the tube plates 225a and 225b of the cartridge headers 220a and 220b increase in temperature. The heat insulators 227a and 227b of the first cartridge header 220a and the second cartridge header 220b suppress the strength of the tube plates 225a and 225b from being reduced due to high temperature and corrosion due to the oxidizing agent contained in the oxidizing gas O1. Further, the heat insulators 227a and 227b suppress thermal deformation of the tube plates 225a and 225b.

  As described above, the oxidant gas O1 in the power generation chamber 215 and the fuel gas F1 passing through the inside of the plurality of cell stacks 101 arranged in the power generation chamber 215 are the plurality of fuel cells 105 in the cell stack 101. Electrochemical reaction with As a result, power generation is performed by the plurality of fuel cells 205.

  The direct current obtained by the power generation in the plurality of fuel cells 205 flows to the end side of the cell stack 101 through the interconnector 107 provided between the plurality of fuel cells 205, and this cell stack 101 Into the lead film 115. Then, this direct current flows from the lead film 115 to the current collecting rod (not shown) of the cartridge 201 via the current collecting plate (not shown), and is taken out of the cartridge 201. The plurality of current collecting rods are connected in series and / or in parallel to each other. Of the current collecting rods, the most downstream current collecting rod is connected to, for example, an inverter not shown. The direct current taken out of the cartridge 201 flows through, for example, an inverter through a plurality of current collector rods connected in series and / or in parallel, where it is converted into an alternating current and supplied to an electric power load.

  The fuel gas F <b> 1 flowing on the inner peripheral side of the cell stack 101 and the oxidant gas O <b> 1 flowing on the outer peripheral side of the cell stack 101 exchange heat through the cell stack 101. As a result, the fuel gas F1 is heated by the oxidant gas O1, and the oxidant gas O1 is cooled by the fuel gas F1. In the present embodiment, the fuel gas F1 and the oxidant gas O1 flow oppositely on the inner peripheral side and the outer peripheral side of the cell stack 101. For this reason, the heat exchange rate between the fuel gas F1 and the oxidant gas O1 is increased, and the cooling efficiency of the oxidant gas O1 by the fuel gas F1 and the heating efficiency of the fuel gas F1 by the oxidant gas O1 are increased. Therefore, in this embodiment, the oxidant gas O1 is cooled to a temperature at which the tube plate 225a and the like forming the first cartridge header 220a are not buckled and deformed, and then the oxidant gas discharge chamber of the first cartridge header 220a. 218 flows into. In the present embodiment, the fuel gas F1 is preheated to a temperature suitable for power generation in the cell stack 101 in the power generation chamber 215 without using a heater or the like.

  In the present embodiment, the fuel gas F1 and the oxidant gas O1 flow oppositely on the inner peripheral side and the outer peripheral side of the cell stack 101, that is, the fuel gas F1 and the oxidant gas O1 flow in opposite directions. However, this is not always necessary. For example, the fuel gas F1 and the oxidant gas O1 may flow in the same direction on the inner peripheral side and the outer peripheral side of the cell stack 101, or the oxidant gas O1 may flow into the fuel gas F1. It may flow in a direction perpendicular to the direction.

  As shown in FIG. 3, the plurality of cylindrical cartridges 201 are all arranged in the pressure vessel 10 such that the cartridge central axis Ac is parallel to the vessel central axis Av of the pressure vessel 10. That is, in the present embodiment, the cartridge center axis Ac extends in the vertical direction, like the container center axis Av.

  The configuration of the cartridge 201 is not limited to that described above, and the cartridge may be arranged so as to extend in a direction orthogonal to the central axis of the pressure vessel. Further, the cartridge is not limited to a cylindrical shape, and may be a prismatic shape.

Next, the operation of the combined power generation system 1 having the above configuration will be described.
When the combined power generation system 1 is in steady operation, the air compressor 4 sucks and compresses the oxidant gas O1 from the air supply unit by the operation of the gas turbine 3. The compressed oxidant gas O <b> 1 flows from the air compressor 4 into the cartridge 201 of the fuel cell module 2 through the oxidant gas pipe 330.

  On the other hand, the fuel gas F <b> 1 supplied from the fuel supply source 20 is supplied to the cartridge 201 of the fuel cell module 2 via the fuel pipe 310. The cartridge 201 generates power using the oxidant gas O1 and the fuel gas F1. The exhaust oxidant gas O2 used for power generation is introduced from the cartridge 201 into the combustor 5 through the exhaust oxidant gas pipe 340.

  On the other hand, the exhaust fuel gas F <b> 2 is introduced into the combustor 5 through the exhaust fuel pipe 320. A part of the exhaust fuel gas F2 flows into the fuel pipe 310 via the fuel recirculation pipe 325 when the fuel recirculation blower 15 is driven.

In the combustor 5, the exhaust fuel gas F <b> 2 is burned, and high-temperature and high-pressure exhaust gas is generated. The high-temperature and high-pressure exhaust gas is introduced from the combustor 5 to the turbine 6 to rotate the turbine 6. The turbine 6 generates a rotational driving force by the introduced high-temperature combustion gas, and the driving force of the turbine 6 provided at one end of the rotor rotates the compressor 4 provided at the other end of the rotor. The rotational driving force is also transmitted to the generator 8 to generate power.
As described above, in the combined power generation system 1, power generation is performed by the fuel cell module 2 and the gas turbine 3.

Next, an operation when the fuel cell module 2 stops due to disconnection of electrical connection with the power load system will be described. Since the operation cannot be continued if the electrical connection with the power load system is cut off, the operation shifts to the operation of stopping the combine power generation system 1. First, the cooperation between the fuel cell system 7 and the gas turbine 3 is canceled by closing an on-off valve (not shown).
At the same time, the extraction of electric power from the fuel cell module 2 is stopped, that is, the electrochemical reaction between hydrogen and oxygen in the cell stack 101 is stopped. In this state, since the temperature of the cartridge 201 of the fuel cell system 7 is the power generation temperature, it is kept at 700 ° C. or higher. Further, a large amount of water vapor generated by the electrochemical reaction in the cell stack 101 is contained in the mixed gas of the fuel gas F1 flowing through the fuel pipe 310 and the recirculated exhaust fuel gas F2 before the fuel cell module is stopped. Contains. However, when the electrochemical reaction stops, water vapor is not generated. Therefore, if the reforming reaction at the fuel electrode is continued after the fuel cell module 2 is stopped, the amount of water vapor (moisture) in the fuel pipe 310 decreases, and the fuel gas F1 containing hydrocarbons is supplied to the cell stack 101. However, not only hydrogen is generated but also carbon may be deposited. As for the supply amount of water vapor, it is desirable that the ratio of water vapor to carbon (S / C) in the fuel pipe 310 is S / C> 3.

  The fuel cell system 7 of the present embodiment operates the water vapor supply device 30 when the power generation by the cell stack 101 is stopped. That is, water is supplied from the water supply source 32 of the water vapor supply device 30 to the vaporizer 31 via the first pipe 33. The water supplied to the vaporizer 31 becomes water vapor when the vaporizer 31 recovers sensible heat inside the pressure vessel. That is, as shown in FIG. 7, the temperature gradually decreases immediately after stopping, but the water in the vaporizer 31 is heated by using the heat of the temperature of the power generation chamber to generate water vapor.

When the combined power generation system 1 is stopped, nitrogen is introduced from the nitrogen generation source 81 into the fuel pipe 310.
The water vapor generated in the vaporizer 31 flows into the fuel pipe 310 through the second pipe 34 and flows into the cell stack 101 of the cartridge 201 together with nitrogen. As described above, in the fuel electrode 112 of the cell stack 101, Ni that is a component of the fuel electrode 112 acts as a catalyst for the fuel gas F1. Therefore, the water vapor reacts with methane (hydrocarbon, CH ₄ ) contained in the fuel gas F1, and reforms into hydrogen (H ₂ ) and carbon monoxide (CO).
Hydrogen generated by the reforming flows into the cell stack 101 together with nitrogen, and keeps the inside of the cell stack 101 in a reducing atmosphere.

  According to the above embodiment, when the combined power generation system 1 is stopped, such as when a trip occurs, water vapor is supplied from the water vapor supply device 30 to the cell stack 101, and hydrogen is generated from this water vapor by the catalyst of the fuel electrode 112 of the cell stack 101. Generated. Thereby, the facilities for holding hydrogen, such as a hydrogen cylinder, are not required, and it is possible to provide a steam supply means that uses the heat of the power generation chamber to reduce the facility cost.

  Moreover, since water vapor | steam supplied to the cell stack 101 at the time of a stop is generated by heating water with the heat | fever which the cell stack 101 emits, it becomes possible to generate water vapor | steam also at the time of the power failure of the combined power generation system 1. . Further, since the heat of the cell stack 101 is used, it is possible to contribute to cooling of the cell stack 101.

  Furthermore, by disposing the vaporizer 31 inside the pressure vessel 10 and around the cell stack 101, the heat generated by the cell stack 101 is transmitted by the vaporizer 31, and the generation efficiency of water vapor can be improved. .

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the fuel cell system 7 of the present invention has been described using the combined cycle power generation system 1 having the fuel cell system 7 including the fuel cell module 2 and the gas turbine 3, but the present invention is not limited thereto. There is nothing. The fuel cell system of the present invention can be applied to a fuel cell system having a single fuel cell module and a micro gas turbine combined power generation system.

1 Combined power generation system 2 Fuel cell module (fuel cell)
7 Fuel Cell System 10 Pressure Vessel 30 Water Vapor Supply Device (Water Vapor Supply Means)
31 Vaporizer 32 Water supply source 33 First piping (piping)
101 Cell stack 112 Fuel electrode (catalyst)
F1 fuel gas F2 exhaust fuel gas O1 oxidant gas O2 exhaust oxidant gas

Claims (4)

A cell stack including a cell that generates electricity by a reaction between an oxidant gas containing oxygen and hydrogen, and a catalyst having a reforming ability to generate hydrogen from hydrocarbon and steam;
Water vapor supply means for supplying water vapor to the cell stack when power generation is stopped in the cell stack;
A fuel cell system comprising: a vaporizer that heats water with heat generated by the cell stack to generate water vapor. The fuel cell system includes a pressure vessel in which the cell stack is accommodated,
The water vapor supply means includes the vaporizer provided inside the pressure vessel, and a pipe connecting the water supply source provided outside the pressure vessel and the vaporizer. The fuel cell system according to claim 1.   3. The fuel cell system according to claim 2, wherein the water vapor supply unit includes a valve that is provided in the pipe and is opened when the vehicle is stopped.   4. The pressure accumulator according to claim 2, further comprising a pressure accumulator connected to the pipe and filled with gas in a compressed state to pressurize water supplied from the water supply source. 5. Fuel cell system.

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