JP5269447B2 - High-temperature fuel cell system and operation method thereof - Google Patents

Description

  The present invention relates to a high-temperature fuel cell system such as a solid oxide fuel cell (hereinafter referred to as SOFC) system.

  The SOFC system usually reforms hydrocarbon fuels such as kerosene and city gas to generate reformed gas as hydrogen-containing gas, and electrochemically generates reformed gas and air. SOFC for reaction is included. The SOFC is usually operated at a high temperature of 550 to 1000 ° C.

  When the SOFC system is stopped, it is desired to replace the reformed gas (flammable gas) supplied to the reformer and the fuel electrode chamber (anode chamber) of the SOFC with a gas that does not ignite. In addition, it is desirable to supply an inert gas to the reformer and the fuel electrode chamber from the viewpoint of preventing oxidative deterioration of the reforming catalyst and the anode electrode provided in the reformer.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 3-257762) discloses a method of purging the reformer and the fuel cell fuel electrode by supplying nitrogen gas from a nitrogen gas supply facility as a replacement gas when the fuel cell system is stopped. Disclosed.

Patent Document 2 (Japanese Patent Application Laid-Open No. 2003-229149) discloses a method of supplying a reforming material (city gas) as a replacement gas and purging the reformer and the fuel cell fuel electrode when the fuel cell system is stopped. Is disclosed.
JP-A-3-257762 JP 2003-229149 A

  When the replacement gas is nitrogen gas, a nitrogen gas supply facility such as a nitrogen cylinder is required, a large installation space is required, and costs such as replacement and supplementation of the nitrogen cylinder are required.

  When the replacement gas is used as the reforming material, the reforming material gas is wasted, and the power generation efficiency for the input material is reduced. Moreover, although combustible gas will stay in a system, it is also considered that combustible gas mixes with oxidizing agents, such as air, and it is desirable to avoid this. Further, when the reforming catalyst or the fuel cell main body is at a high temperature, the hydrocarbon raw material may be thermally decomposed and coked on the reforming catalyst or the fuel cell fuel electrode, thereby degrading the performance.

  The above applies not only to SOFC systems but also to molten carbonate fuel cell systems.

  As described above, there are problems to be examined when stopping the high-temperature fuel cell system. In particular, since what can be performed during an emergency stop is limited, it is difficult to purge the reformer and the fuel cell with an inert gas in a space-saving and low-cost manner.

  An object of the present invention is to provide a high-temperature fuel cell system capable of purging a reformer and a fuel cell with an inert gas in a space-saving and low cost, and an emergency stop method thereof.

According to the present invention, an emergency stop method for a high-temperature fuel cell system comprising a reformer that reforms a hydrocarbon-based fuel to produce a reformed gas, and a high-temperature fuel cell that generates electric power using the reformed gas Because
The water supplied from the emergency stop water supply facility is vaporized, and the resulting steam is supplied to the reformer and the anode chamber of the high-temperature fuel cell, and the interior of the reformer and the anode chamber of the high-temperature fuel cell is steamed. An emergency stop method for a high-temperature fuel cell system is provided.
However, here, the amount of water supplied from the emergency stop water supply facility is set to the minimum amount that can purge the space from the reformer to the exhaust port from which the exhaust gas is discharged from the high-temperature fuel cell system. .
In order to vaporize the water supplied from the emergency stop water supply facility, a vaporizer disposed at a position that receives heat radiation from the high-temperature fuel cell can be used.

  In this method, the emergency stop water supply facility may include a container containing pressurized water and a valve that is opened during an emergency stop. .

  In this method, a vaporizer provided with a heat storage material can be used to vaporize the water supplied from the emergency stop water supply facility.

  In this method, the high temperature fuel cell system may have a normal water supply facility separately from the emergency stop water supply facility.

  In this method, the reformer can include a reforming catalyst capable of promoting a steam reforming reaction.

According to the present invention, there is provided a high-temperature fuel cell system having a reformer that reforms a hydrocarbon-based fuel to produce a reformed gas, and a high-temperature fuel cell that generates electric power using the reformed gas,
Water supply equipment for emergency stop,
A vaporizer for vaporizing water supplied from the emergency stop water supply facility;
There is provided a high temperature fuel cell system further comprising a line for supplying steam obtained from the vaporizer to the reformer and the anode chamber of the high temperature fuel cell.
However, here, the water supply facility for emergency stop contains a minimum amount of water that can purge the space from the reformer to the exhaust port from which the exhaust gas is discharged from the high-temperature fuel cell system.
The vaporizer may be disposed at a position to receive heat radiation from the high temperature fuel cell.

  In this system, the emergency stop water supply facility may include a container capable of storing pressurized water and a valve opened during an emergency stop.

  In this system, the vaporizer can include a heat storage material.

  In this system, the high temperature fuel cell system may have a normal water supply facility separately from the emergency stop water supply facility.

  In this system, the reformer can include a reforming catalyst capable of promoting a steam reforming reaction.

  According to the present invention, a high-temperature fuel cell system capable of purging a reformer and a fuel cell with an inert gas in a space-saving and low cost and an emergency stop method thereof are provided.

  In the present invention, the high-temperature fuel cell system includes a reformer that reforms a hydrocarbon fuel to produce a reformed gas, and a high-temperature fuel cell that generates electric power using the reformed gas.

  At the time of emergency stop, the water supplied from the emergency stop water supply facility is vaporized, and the obtained steam is supplied to the reformer and the anode chamber of the high-temperature fuel cell, so that the reformer and the high-temperature fuel cell are supplied. The step of purging the inside of the anode chamber with steam is performed.

  For this purpose, an emergency stop water supply facility, a vaporizer for vaporizing water supplied from the emergency stop water supply facility, and steam obtained from the vaporizer are used as a reformer and an anode chamber of a high-temperature fuel cell. A high-temperature fuel cell system having a line for supplying to the battery can be used. In this line, it is not necessary that steam can be separately supplied to the reformer and the anode chamber, and steam may be sequentially supplied to the reformer and the anode chamber. That is, a line that can supply steam to the reformer and supply steam discharged from the reformer to the anode chamber can be used.

  Hereinafter, one embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. Here, an SOFC system including an indirect internal reforming SOFC having a reformer in the vicinity of the SOFC will be described.

[Indirect internal reforming SOFC]
1 and 2 schematically show an embodiment of an indirect internal reforming SOFC system. FIG. 1 shows a normal state, and FIG. 2 shows an emergency stop state.

  The indirect internal reforming SOFC is a reformer 2 that reforms hydrocarbon fuel to produce reformed gas (hydrogen-containing gas), SOFC3 that generates power using the reformed gas, and exhausts from the anode chamber of the SOFC It has a combustion zone 4 for burning the anode off gas to be burned, and a housing 5 for accommodating the reformer, the SOFC and the combustion zone.

  The reformer includes a reforming catalyst layer 2a. In addition, an igniter 6 is provided as an ignition means for igniting the anode off gas.

  The indirect internal reforming SOFC refers to a casing (module container) 5 and equipment included therein.

  A vaporizer 8 for emergency stop is further accommodated in the housing. In the emergency stop vaporizer 8, a heat storage material 8a is accommodated.

  As the heat storage material, a material having resistance to the use environment and having a heat storage effect can be appropriately used. For example, the container forming the vaporizer can be filled with a ceramic material such as an alumina ball.

  Each supply fluid is appropriately preheated as needed and then supplied to the reformer or SOFC.

  As shown in FIG. 1, during normal times (such as during power generation), hydrocarbon-based fuel and steam are supplied to the reformer 2, particularly the reforming catalyst layer 2a. At this time, water is supplied from the normal-time water supply facility to the vaporizer (normal-time vaporizer) 1, and steam is obtained from the normal-time vaporizer 1.

  As the normal-time water supply facility, facilities capable of continuously supplying water can be used as appropriate. Here, the solenoid valve 11 which closes at the time of emergency stop is connected to a tap water piping, and it is set as the normal time water supply equipment. A flow control valve (not shown) or the like is also used as appropriate. Here, an electromagnetic valve is used as a valve that closes at the time of an emergency stop. However, the valve is not limited thereto, and a valve driven by air or the like can be used. As this electromagnetic valve, an electromagnetic valve that closes when power supply is lost can be used.

  As a heat source in the normal-time vaporizer 1, high-temperature gas in the system can be used as appropriate. Here, gas discharged from the module container 5 is used.

  Further, the hydrocarbon fuel can be appropriately supplied to the reformer. Here, the hydrocarbon-based fuel is supplied to the reformer via the electromagnetic valve 12 that is closed at the time of emergency stop. When liquid fuel such as kerosene is used as the hydrocarbon-based fuel, the hydrocarbon-based fuel can be appropriately vaporized and then supplied to the reformer.

  The hydrocarbon fuel is reformed in the reformer, and a reformed gas containing hydrogen is obtained. The reformed gas obtained from the reformer is supplied to the SOFC 3, particularly the anode chamber thereof. In addition, air is appropriately preheated and supplied to the cathode chamber of the SOFC.

  The combustible component in the anode off gas (gas discharged from the anode) is burned by oxygen in the cathode off gas (gas discharged from the cathode) in the combustion region 4 at the SOFC outlet. For this purpose, ignition can be performed using the igniter 6. The outlets of both the anode and the cathode are opened in the module container 5. Combustion gas is exhausted from the module container, heat is recovered as appropriate, and exhausted outside the system.

  At normal times, the valve 11 for normal water supply equipment and the valve 12 for hydrocarbon fuel supply are opened, and the valve 13 used at the time of emergency stop is closed.

  At the time of emergency stop, as shown in FIG. 2, the valves 11 and 12 are closed and the valve 13 is opened. The supply of water for normal time and hydrocarbon fuel is stopped, and the supply of water for emergency stop is started. The supply of cathode gas (air) is also stopped.

  The emergency stop water supply facility includes a container (emergency stop water tank) 7 that can store pressurized water, and an electromagnetic valve 13 that is opened during an emergency stop. Water is injected into the emergency stop water tank 7. When the valve 13 is opened, water is supplied to the vaporizer 8 by the pressure. If water is supplied using the pressure in the water tank in this way, water can be supplied without any external energy supply such as a power source. Here, an electromagnetic valve is used as a valve that is opened at the time of an emergency stop. However, the valve is not limited thereto, and a valve driven by air or the like can be used. As this electromagnetic valve, an electromagnetic valve that is opened when power supply is lost can be used.

  In order to accommodate water in the emergency stop water tank in a pressure state, the water can be compressed and placed in the emergency stop water tank. Further, an inert gas such as nitrogen may be compressed into a part of the emergency stop water tank or a container (accumulator) connected to the water tank. Or you may press-fit water into a water tank using the pressure of water supply. In preparation for when the water supply pressure for pressing water into the emergency stop water tank is excessive, the water tank may be provided with a depressurization valve. Thereby, when the pressure is excessive, the pressure can be released out of the system by the pressure reducing valve.

  Now, the heat storage material 8a is accommodated in the emergency stop vaporizer 8, and water is vaporized by the heat stored in the heat storage material, thereby generating steam. By introducing the generated steam into the reformer, steam can be supplied to the reformer and the anode chamber of the SOFC, and the residual reformed gas and the inside of the reformer and the anode chamber of the high-temperature fuel cell can be supplied. Unreacted fuel can be purged.

  In addition, when the reforming catalyst is a catalyst that can promote the steam reforming reaction, by supplying steam to the remaining unreacted fuel on the reforming catalyst, the complete reforming of the unreacted fuel is promoted and the unreacted fuel is not reacted. The fuel can be purged. As a result, the deterioration due to coke deposition of the reforming catalyst and the fuel cell downstream of the reformer can be excellently prevented.

  In addition to the reformer and SOFC, the emergency stop vaporizer is also housed in a single module container and modularized. The reformer and the emergency stop vaporizer are arranged at a position where heat can be received from the SOFC. For example, if the reformer and the emergency stop carburetor are arranged at a position where they receive heat radiation from the SOFC, the reformer and the emergency stop carburetor are heated by the heat radiation from the SOFC during power generation.

  In the indirect internal reforming SOFC, the reformer and the emergency stop carburetor are preferably arranged at a position where radiation heat can be directly transferred from the SOFC to the outer surface of the reformer and the emergency stop carburetor. . Therefore, it is preferable that substantially no shielding is disposed between the reformer and the SOFC and between the emergency stop vaporizer and the SOFC. That is, it is preferable to make a gap between the reformer and the SOFC and between the emergency stop vaporizer and the SOFC. Moreover, it is preferable to shorten the distance between the reformer and the SOFC and the distance between the emergency stop vaporizer and the SOFC as much as possible.

  The reformer 2 and the emergency stop vaporizer 8 are heated by the combustion heat of the anode off gas generated in the combustion region 4. Also, when the SOFC is hotter than the reformer, the reformer is also heated by the radiant heat from the SOFC, and when the SOFC is hotter than the vaporizer for emergency stop, the radiant heat from the SOFC also The emergency stop vaporizer is heated.

  Furthermore, the reformer may be heated by heat generated by reforming. If the reforming is partial oxidation reforming or autothermal reforming (autothermal reforming) and the heat generation by the partial oxidation reforming reaction is greater than the endothermic reaction by the steam reforming reaction, Fever accompanies.

  The reformer 2 and the vaporizer 8 can be integrated. For example, the heat storage material can be accommodated on the upstream side in one container, and the reforming catalyst can be accommodated on the downstream side.

  In the embodiment described above, the emergency stop water supply facility has a container containing pressurized water and an electromagnetic valve that is opened during an emergency stop. This mode is preferable from the viewpoint that external energy supply (power source or the like) is not necessary for water supply during an emergency stop.

  In the form demonstrated above, in order to vaporize the water supplied from the emergency stop water supply equipment, the vaporizer which accommodated the heat storage material is used. This form is preferable from the viewpoint that external energy supply (power supply or the like) is not required for water vaporization during an emergency stop.

  It is possible to store heat in the heat storage material by using heat generated by the fuel cell at normal times when the fuel cell is generating power. The heat storage material may be provided inside the housing and may use off-gas combustion heat or may use radiant heat transfer from the fuel cell. In addition, the heat storage material is not limited to the inside of the housing, and may have a form in which a heat exchanger is provided outside and heat is stored by exchanging heat with exhaust gas.

  In the embodiment described above, the high-temperature fuel cell system has a normal time water supply facility separately from the emergency stop water supply facility. In addition, although the case where the reformed gas is obtained by steam reforming is described, the hydrogen source by steam reforming is not only the hydrogen content contained in the hydrocarbon that is the raw material, but water is also the hydrogen source. This is preferable in terms of increasing the hydrogen concentration in the gas. The same applies to the case where the reformed gas is obtained by autothermal reforming.

  In the form described above, the reformer contains a reforming catalyst capable of promoting the steam reforming reaction. This form is preferable from the viewpoint that the hydrocarbon-based fuel remaining in the reformer can be reformed during an emergency stop, and coking in the SOFC can be more reliably prevented.

  As the reforming catalyst capable of promoting the steam reforming reaction, a steam reforming catalyst or an autothermal reforming catalyst can be used.

  The amount of water supplied from the emergency stop water supply facility should be the minimum amount that can sufficiently purge the space from the reformer to the exhaust gas outlet (exhaust port from which exhaust gas is discharged from the fuel cell system). This is preferable from the viewpoint of preventing condensation in the system. In the above form, the amount of water to be pressed into the emergency stop water tank 7 can be set to this minimum amount.

  As the minimum amount that can be sufficiently purged, the volume of the reformer, the volume from the reformer to the inlet of the anode chamber, the volume of the anode chamber, the combustion chamber (in the form shown in FIG. 1, the combustion gas in the casing can flow) The volume obtained by adding up the volume and the exhaust gas line volume from the combustion chamber to the exhaust port can be adopted. This minimum amount can be calculated from the volume of the structure, and an amount that can be purged by a preliminary test can be determined in advance. The amount of water accommodated in the emergency stop water tank can be determined so that this minimum amount of steam can be generated.

  When the reformer and the fuel cell electrode chamber are used at atmospheric pressure, the pressurized state in the case of the pressurized water refers to a state where the pressure is increased to a pressure higher than the atmospheric pressure. Further, when the reformer and / or the fuel cell electrode chamber are used under a pressure higher than the atmospheric pressure, this indicates a state where the pressure is increased to a pressure higher than the working pressure. That is, the pressure is higher than the working pressure of the portion to be purged.

  It is preferable from the viewpoint of preventing damage to the fuel cell system that the water supply pressure for emergency stop (discharge pressure when water is supplied from the water tank for emergency stop) is equal to or lower than the pressure resistance of the fuel cell system. The pressure resistance of the fuel cell system means the lowest pressure resistance among members constituting the fuel cell system, such as pipes, pipe joints, fuel cell members, and housings. The pressure resistance of each member can be obtained by a preliminary test. In order to make the water supply pressure for emergency stop below the pressure resistance of the fuel cell system, it is possible to pressurize and fill the water while controlling the pressure control device below the pressure resistance value of the fuel cell system. It is preferable to provide a safety valve that operates at a pressure value or higher.

  The normal-time water vaporizer is outside the housing in the form shown in FIGS. 1 and 2, but is not limited thereto, and may be provided inside the housing. Further, not only water but also liquid fuel can be vaporized when using liquid fuel. The normal fuel vaporizer for liquid fuel may be separate from or integral with the normal water vaporizer. The normal-time water vaporizer may be integrated with the reformer or may be a separate body.

  When using raw materials that do not require water vaporization (when the hydrocarbon fuel is a gas body such as LPG or methane and reforming is performed by partial oxidation), a normal water vaporizer is not required. . However, when the hydrocarbon fuel is humidified, it may be vaporized using a vaporizer as appropriate.

  In the case of an emergency stop, for example, in the event of a power failure when the power supply to the fuel cell system auxiliary equipment (raw material supply system, control system, measurement system, etc.) is stopped, system temperature abnormality, control abnormality, It means a state in which the operation of the system is stopped urgently without performing a normal stop process (cannot be performed) due to an earthquake or the like, in a state where control is difficult or no external energy is supplied.

  The emergency stop water supply facility means a water supply facility that can operate independently without control or external energy supply.

  “Normal time” means a state where power generation is performed manually or automatically in a state where no abnormality has occurred as in an emergency stop. In this state, power and heat are supplied from the fuel cell.

  The normal-time water supply facility means, for example, a facility that supplies water for a reforming raw material when performing a steam reforming reaction. The present invention is also applicable when the reformed gas is obtained by autothermal reforming. In addition, the present invention can be applied to the case where the fuel is humidified when performing partial oxidation reforming.

  The heat storage material means a material that can receive heat and store heat in normal times. From the viewpoint of vaporizing water during an emergency stop and from the viewpoint of reducing the volume of the emergency stop vaporizer, those having a large heat capacity are preferable.

[Case]
As the casing (module container) used for the indirect internal reforming SOFC, an appropriate container capable of accommodating the SOFC, the reformer, and the combustion region can be used. As the material, for example, an appropriate material having resistance to the environment to be used, such as stainless steel, can be used. The container is appropriately provided with a connection port for gas exchange and the like.

  The module container is preferably airtight so that the interior of the module container does not communicate with the outside (atmosphere).

(Combustion area)
The combustion region is a region where the anode off gas discharged from the anode of the SOFC can be combusted. For example, the anode outlet can be opened in the housing, and the space near the anode outlet can be used as a combustion region. This combustion can be performed using, for example, a cathode off gas as the oxygen-containing gas. For this purpose, the cathode outlet can be opened in the housing.

  An ignition means such as an igniter can be appropriately used to burn the combustion fuel or anode off gas.

  The indirect internal reforming SOFC system has been described above as an example. However, the present invention is not limited thereto, and the present invention can also be applied to an external reforming SOFC system.

  The present invention can also be applied to high temperature fuel cells. That is, the present invention can be applied to a molten carbonate fuel cell (MCFC) system in addition to the SOFC.

[Hydrocarbon fuel]
The hydrocarbon-based fuel is appropriately selected from compounds or mixtures thereof containing carbon and hydrogen (may contain other elements such as oxygen) known in the field of high-temperature fuel cells as a reformed gas raw material. Compounds having carbon and hydrogen in the molecule such as hydrocarbons and alcohols can be used. For example, hydrocarbon fuels such as methane, ethane, propane, butane, natural gas, LPG (liquefied petroleum gas), city gas, gasoline, naphtha, kerosene, light oil, etc., alcohols such as methanol and ethanol, ethers such as dimethyl ether, etc. is there.

  Of these, kerosene and LPG are preferred because they are readily available. Moreover, since it can be stored independently, it is useful in areas where city gas lines are not widespread. Furthermore, SOFC power generators using kerosene or LPG are useful as emergency power supplies. In particular, kerosene is preferable because it is easy to handle.

[Reformer]
The reformer produces a reformed gas containing hydrogen from a hydrocarbon fuel.

  In the reformer, any of steam reforming, partial oxidation reforming, and autothermal reforming accompanied by a partial oxidation reaction in the steam reforming reaction may be performed.

  The reformer is appropriately equipped with a steam reforming catalyst having steam reforming ability, a partial oxidation reforming catalyst having partial oxidation reforming ability, and a self-thermal reforming catalyst having both partial oxidation reforming ability and steam reforming ability. Can be used.

  As the structure of the reformer, a structure known as a reformer can be appropriately adopted. For example, it is possible to have a structure having a region for accommodating the reforming catalyst in a sealable container and having an inlet for fluid necessary for reforming and an outlet for reforming gas.

  The material of the reformer can be appropriately selected and adopted from materials known as reformers in consideration of resistance in the use environment.

  The shape of the reformer can be an appropriate shape such as a rectangular parallelepiped or a circular tube.

  Supply hydrocarbon-based fuel (pre-vaporized if necessary), water vapor, and oxygen-containing gas such as air, if necessary, individually or appropriately mixed to the reformer (reforming catalyst layer) can do. The reformed gas is supplied to the anode of the high temperature fuel cell.

[High-temperature fuel cell]
INDUSTRIAL APPLICABILITY The present invention can be suitably applied to a system including a high-temperature fuel cell in which the fuel cell is hot and can store the heat during normal operation and can be used in an emergency stop. Such fuel cells include SOFC and MCFC.

  As the SOFC, various known shapes such as a flat plate type and a cylindrical type can be appropriately selected and used. In the SOFC, oxygen ion conductive ceramics or proton ion conductive ceramics are generally used as an electrolyte.

  The MCFC can be appropriately selected from known MCFCs.

  The SOFC or MCFC may be a single cell, but in practice, a stack in which a plurality of single cells are arranged (in the case of a cylindrical type, it may be called a bundle, but the stack referred to in this specification also includes a bundle) Is preferably used. In this case, one or more stacks may be used.

[Reforming catalyst]
Any of the steam reforming catalyst, partial oxidation reforming catalyst, and autothermal reforming catalyst used in the reformer can be a known catalyst. Examples of the partial oxidation reforming catalyst include platinum-based catalysts, examples of the steam reforming catalyst include ruthenium-based and nickel-based catalysts, and examples of the autothermal reforming catalyst include rhodium-based catalysts. Examples of reforming catalysts that can promote combustion include platinum-based and rhodium-based catalysts.

[Reformer operating conditions]
Hereinafter, the conditions during rated operation and stop operation in the reformer will be described for each of steam reforming, autothermal reforming, and partial oxidation reforming.

In steam reforming, steam is added to reforming raw materials such as kerosene. The reaction temperature of the steam reforming can be performed, for example, in the range of 400 ° C to 1000 ° C, preferably 500 ° C to 850 ° C, more preferably 550 ° C to 800 ° C. The amount of steam introduced into the reaction system is defined as the ratio of the number of moles of water molecules to the number of moles of carbon atoms contained in the hydrocarbon fuel (steam / carbon ratio), and this value is preferably 1 to 10, more preferably 1.5-7, more preferably 2-5. When the hydrocarbon fuel is liquid, the space velocity (LHSV) at this time is A / B when the flow rate in the liquid state of the hydrocarbon fuel is A (L / h) and the catalyst layer volume is B (L). This value is preferably set in the range of 0.05 to 20 h ⁻¹ , more preferably 0.1 to 10 h ⁻¹ , and still more preferably 0.2 to 5 h ⁻¹ .

  In autothermal reforming, an oxygen-containing gas is added to the reforming raw material in addition to steam. The oxygen-containing gas may be pure oxygen, but air is preferred because of its availability. An oxygen-containing gas can be added so that the endothermic reaction accompanying the steam reforming reaction is balanced, and a heat generation amount capable of maintaining the temperature of the reforming catalyst layer and SOFC or raising the temperature thereof can be obtained. The addition amount of the oxygen-containing gas is preferably 0.005 to 1, more preferably 0.01 to 0.00 as the ratio of the number of moles of oxygen molecules to the number of moles of carbon atoms contained in the hydrocarbon fuel (oxygen / carbon ratio). 75, more preferably 0.02 to 0.6. The reaction temperature of the autothermal reforming reaction is set, for example, in the range of 400 ° C to 1000 ° C, preferably 450 ° C to 850 ° C, more preferably 500 ° C to 800 ° C. When the hydrocarbon fuel is liquid, the space velocity (LHSV) at this time is preferably selected in the range of 0.05 to 20, more preferably 0.1 to 10, and further preferably 0.2 to 5. The amount of steam introduced into the reaction system is preferably 1 to 10, more preferably 1.5 to 7, and still more preferably 2 to 5 as a steam / carbon ratio.

  In partial oxidation reforming, an oxygen-containing gas is added to the reforming raw material. The oxygen-containing gas may be pure oxygen, but air is preferred because of its availability. In order to secure a temperature for proceeding the reaction, the amount added is appropriately determined in terms of heat loss and the like. The amount is preferably 0.1 to 3, more preferably 0.2 to 0.7 as the ratio of the number of moles of oxygen molecules to the number of moles of carbon atoms contained in the hydrocarbon fuel (oxygen / carbon ratio). . The reaction temperature of the partial oxidation reaction can be set, for example, in the range of 450 ° C to 1000 ° C, preferably 500 ° C to 850 ° C, and more preferably 550 ° C to 800 ° C. When the hydrocarbon fuel is a liquid, the space velocity (LHSV) at this time is preferably selected in the range of 0.1-30. Steam can be introduced to suppress the generation of soot in the reaction system, and the amount thereof is preferably 0.1 to 5, more preferably 0.1 to 3, more preferably 1 to 1, as a steam / carbon ratio. 2.

[Other equipment]
Known components of the high-temperature fuel cell system can be appropriately provided as necessary. Specific examples include a vaporizer for vaporizing liquid, a pump for pressurizing various fluids, a pressure increasing means such as a compressor and a blower, a valve for adjusting the flow rate of the fluid, or for blocking / switching the flow of the fluid. Such as flow rate control means, flow path blocking / switching means, heat exchanger for heat exchange / recovery, condenser for condensing gas, heating / heat-retaining means for externally heating various devices with steam, etc., hydrocarbon system Fuel (reforming raw materials) and combustion fuel storage means, instrumentation air and electrical systems, control signal systems, control devices, output and power electrical systems, desulfurization to reduce the concentration of sulfur in the fuel Such as a vessel.

  The present invention can be applied to, for example, a high-temperature fuel cell system used in a stationary or moving power generator or a cogeneration system.

It is a schematic diagram which shows the outline | summary of the indirect internal reforming type | mold SOFC system which can apply this invention, Comprising: It is a figure for demonstrating the state at the time of normal. It is a schematic diagram which shows the outline | summary of the indirect internal reforming type | mold SOFC system which can apply this invention, Comprising: It is a figure for demonstrating the state at the time of an emergency stop.

Explanation of symbols

1 Water vaporizer for normal use 2 Reformer 2a Reforming catalyst layer 3 SOFC
4 Combustion area 5 Housing 6 Igniter 7 Water tank for emergency stop 8 Water vaporizer for emergency stop 8a Heat storage material 11 Valve (closed at emergency stop)
12 Valve (closed at emergency stop)
13 Valve (open at emergency stop)

Claims (12)

An emergency stop method for a high-temperature fuel cell system comprising a reformer that reforms a hydrocarbon fuel to produce a reformed gas, and a high-temperature fuel cell that generates power using the reformed gas,
The water supplied from the emergency stop water supply facility is vaporized, and the resulting steam is supplied to the reformer and the anode chamber of the high-temperature fuel cell, and the interior of the reformer and the anode chamber of the high-temperature fuel cell is steamed. have a in purging process,
The amount of water supplied from the emergency stop water supply facility is the minimum amount that can purge the space from the reformer to the exhaust port from which the exhaust gas is discharged from the high-temperature fuel cell system. Method for emergency stop of fuel cell system The method according to claim 1, wherein a vaporizer disposed at a position to receive heat radiation from the high-temperature fuel cell is used to vaporize water supplied from the emergency stop water supply facility. The method according to claim 1 or 2, wherein the emergency stop water supply facility has a container containing pressurized water and a valve opened during an emergency stop. The method according to any one of claims 1 to 3, wherein a vaporizer including a heat storage material is used to vaporize water supplied from the emergency stop water supply facility. The method according to any one of claims 1 to 4 , wherein the high-temperature fuel cell system includes a normal-time water supply facility separately from the emergency-stop water supply facility. The method according to any one of claims 1 to 5 , wherein the reformer includes a reforming catalyst capable of promoting a steam reforming reaction. A high-temperature fuel cell system comprising a reformer that reforms a hydrocarbon-based fuel to produce a reformed gas, and a high-temperature fuel cell that generates electric power using the reformed gas,
Water supply equipment for emergency stop,
A vaporizer for vaporizing water supplied from the emergency stop water supply facility;
The steam obtained from the vaporizer to further chromatic and supplying line reformer and the anode chamber of the high temperature fuel cell,
The water supply facility for emergency stop contains the minimum amount of water that can purge the space from the reformer to the exhaust outlet from which the exhaust gas is discharged from the high-temperature fuel cell system. Battery system. The vaporizer is disposed at a position to receive heat radiation from the high temperature fuel cell.
The high temperature fuel cell system according to claim 7. 9. The high-temperature fuel cell system according to claim 7, wherein the emergency stop water supply facility includes a container capable of storing pressurized water and a valve opened during an emergency stop. The high temperature fuel cell system according to any one of claims 7 to 9, wherein the vaporizer includes a heat storage material. The high temperature fuel cell system according to any one of claims 7 to 10 , wherein the high temperature fuel cell system has a normal water supply facility separately from the emergency stop water supply facility. The high temperature fuel cell system according to any one of claims 7 to 11 , wherein the reformer includes a reforming catalyst capable of promoting a steam reforming reaction.

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