JP4745618B2 - Operation method of fuel cell structure - Google Patents

Description

  The present invention relates to a method for operating a fuel cell structure. More specifically, the present invention relates to a fuel cell structure including a fuel cell body and a reformer in which a reforming catalyst is accommodated. The present invention relates to an operation method for generating electricity.

In recent years, various fuel cells in which a stack of fuel cells (cells) is housed in a housing have been proposed as next-generation energy. For example, a solid electrolyte fuel cell structure, the cell stack stacked a plurality of fuel cells (cells), a fuel cell body comprising a plurality of sequences at appropriate intervals constructed accommodated in the housing, about 1000 Operated at a temperature of ℃.

  Hydrogen is used as a fuel gas for power generation, hydrogen gas and an oxygen-containing gas (usually air) are supplied into the fuel cell body, the oxygen-containing gas is brought into contact with the oxygen electrode in the cell, Electric power is generated by bringing hydrogen into contact with the fuel electrode in the cell to cause a predetermined electrode reaction.

As a method for supplying hydrogen as a fuel gas, a steam reforming method in which a hydrocarbon such as natural gas reacts with steam to generate hydrogen is used. A reforming reaction between hydrocarbon and steam (an endothermic reaction). ) Is performed at 500 to 900 ° C., there is a problem that the start-up time for heating the reformer that performs the reforming reaction to the reaction temperature is long.

  In order to solve such a problem, a reformer is disposed in a housing that accommodates a cell stack, and heat generated during power generation is used for a steam reforming reaction to increase thermal efficiency. (For example, refer to Patent Document 1).

In addition, heat reforming is performed by partial reforming, which is an exothermic reaction, or a combination of partial oxidation and steam reforming (hereinafter referred to as autothermal method) to shorten the start-up time of the reformer. A reformer that does not require a source has also been reported (see, for example, Patent Document 2).
JP-A-8-287937 JP 2001-185196 A

  However, in the method of Patent Document 1, during steady operation, hydrocarbon gas and steam are supplied into the reformer and hydrogen is generated by steam reforming to be used as fuel gas. The reformer was not reformed, and the water vapor was condensed and liquefied in the main body. As a result, there was a possibility that carbon was deposited by thermal decomposition of the hydrocarbon gas. When carbon deposition occurs, the reforming performance deteriorates due to a decrease in the activity of the reforming catalyst and an increase in pressure loss.

  On the other hand, in the method of Patent Document 2 in which activation is performed using a partial oxidation reaction that is an exothermic reaction, depending on the fuel or catalyst used, catalyst heating is required up to the temperature at which the partial oxidation reaction starts, such as a burner. A separate heat source must be installed, and an excessive temperature rise may occur after the start of the reaction, resulting in the disadvantage of damaging the reformer and the cell.

  Accordingly, an object of the present invention is to provide a method of operating a fuel cell structure using steam reforming, in which carbon deposition is effectively prevented and a special heating source is not used.

According to the present invention, for a fuel cell structure including a fuel cell main body and a reformer in which a reforming catalyst is accommodated, a hydrocarbon-rich fuel is supplied with hydrogen-rich fuel by steam reforming through the reformer. reforming the gas, to generate electricity by supplying an oxygen-containing gas in a separate path to the fuel cell body and the fuel gas supplied to the fuel cell body and the fuel gas is discharged from the fuel cell body is burned gases, in the operating method of the fuel cell structure for discharging the combustion exhaust gas generated by combustion in the external,
During startup, the hydrocarbon gas a mixed gas of the oxygen-containing gas, the supplies to the fuel cell main body through the reformer, the oxygen-containing gas wherein an oxygen-containing gas in a separate path fuel cell body supplied to, and the mixed gas and the oxygen-containing gas different route is burned is discharged from the fuel cell main body, heating the reformer and the fuel cell main body by this combustion heat,
Temperature of the reformer, after the steam reforming is allowed to start, and at the same time to supply steam to the reformer, and stopping the supply to the reformer of the oxygen-containing gas, said hydrocarbon performs steam reforming by the gas passing the reformer, and the oxygen-containing gas in a separate path and the fuel gas reformed hydrogen-rich to generate electricity is supplied to the fuel cell body, the thereby combusting the oxygen-containing gas and the fuel gas discharged from the fuel cell body, the operating method of the fuel cell structure and performs steady operation while discharging the combustion exhaust gas generated by combustion to the outside Provided.

In the present invention, a base metal catalyst or a noble metal catalyst is used as the reforming catalyst, but it is particularly preferable to use a Ni catalyst which is a base metal catalyst. The Ni catalyst has a low oxidation activity. For example, in the case of city gas (CH ₄ ), the reforming reaction start temperature is about 350 ° C. (about 250 to 300 ° C. for the noble metal catalyst), and the part at the start-up (before steam generation) This is advantageous in that oxidation can be effectively suppressed.

Further, the fuel cell body, the cell stack in which a plurality of cells are connected has a plurality ordered structure suitable intervals, the passed through the reformer gas is supplied into the cell stack the discharged into the combustion zone through the interior of each cell, the oxygen-containing gas in another path is supplied to the space between the cell stack, and is it discharged the combustion zone through the outer surface of each cell Is preferred.

  In general, in the present invention, hydrogen-rich fuel gas is supplied to the fuel cell main body by a steam reforming reaction to perform steady operation, but at the time of start-up, until the steam can be generated, the raw fuel is used. A mixed gas of a certain hydrocarbon gas and a certain amount of oxygen-containing gas (starting oxygen-containing gas) is supplied to the fuel cell main body through the reformer, and then the fuel cell rises after the steam can be generated. During steady operation in the temperature process, it is an important feature that the supply of the starting oxygen-containing gas is stopped and the hydrocarbon gas and water vapor are supplied into the fuel cell body through the reformer.

  That is, in both cases of start-up and steady operation, the oxygen-containing gas for power generation is supplied to the fuel cell main body, and the gas passed through the reformer is supplied to the fuel cell main body. The fuel is discharged from the battery body and burned, and the combustion heat causes heating of the reformer for generating and maintaining the steam reforming reaction and heating of the fuel cell body for power generation.

In particular, in the present invention, since a predetermined amount of the start-up oxygen-containing gas is supplied into the reformer together with the hydrocarbon gas at the time of start-up until steam generation is possible, carbon deposition can be effectively avoided. That is, at this stage, the reformer is not heated to the predetermined reforming reaction start temperature, and the hydrocarbon gas is supplied to the fuel cell body without being reformed, but only the hydrocarbon gas is supplied. If the catalyst has reached the reforming reaction start temperature or if the vicinity of the combustion zone has reached a very high temperature, steam is not supplied and there is no oxygen source. Carbon precipitation occurs due to thermal decomposition of hydrocarbons. However, in the present invention, since the oxygen-containing gas is supplied together with the hydrocarbon gas, the rate of temperature rise is fast, and even when the catalyst reaches a high temperature without supplying water vapor, the hydrocarbon is oxidized by an oxidation reaction. This suppresses the thermal decomposition of carbon and can effectively prevent the precipitation of carbon. The mixed molar ratio (O ₂ / C) of oxygen (O ₂ ) and hydrocarbon (C) in the mixed gas is preferably in the range of 0.5 to 1.0.

  Further, in the present invention, the oxygen-containing gas for start-up is supplied at the time of start-up, but the supply of the oxygen-containing gas is stopped and switched to the supply of water-vapor when the steam can be generated. Catalyst reforming is performed without using a partial oxidation reaction, which is an exothermic reaction, and without using a dedicated heat source. For this reason, damage to the reformer due to the exothermic reaction can be effectively avoided, and it is advantageous for miniaturization of the fuel cell structure. In this case, it is preferable to perform the above switching when the catalyst temperature is lower than the reforming reaction start temperature, depending on the type of catalyst or the like used.

  Furthermore, when the vaporization chamber to which the water supply pipe is connected is provided in the lower part of the reforming catalyst housing chamber of the reformer, early temperature rise of the reforming catalyst due to combustion in the combustion zone is suppressed, The partial oxidation reaction at the start-up that is not supplied is also suppressed, and abnormal temperature rise due to the partial oxidation reaction is prevented. In addition, since the gas supply side of the reformer is in communication with the vaporization chamber, the gas supply side of the reformer can be kept at a low temperature (for example, 300 to 600 ° C.) by the heat of vaporization during steady operation. Generation of carbon due to thermal decomposition of gas can be effectively prevented.

Hereinafter, the present invention will be described in detail based on specific examples shown in the accompanying drawings.
FIG. 1 is a diagram for explaining a gas flow in the operation method of the present invention.
FIG. 2 is a diagram showing a schematic structure of a fuel cell structure used in the present invention.
3 is a diagram (a cross-sectional view taken along the line AA in FIG. 2) showing a schematic structure of a cell stack of the fuel cell main body in the fuel cell structure in FIG.

  1 and 2, the fuel cell structure used in the present invention has a structure in which a fuel cell body 1 and a reformer 2 are provided in a predetermined housing (not shown). A combustion zone 3 is formed in the upper part of the fuel cell main body 1, and the reformer 2 is arranged in the upper part of the combustion zone 3. That is, the reformer 2 is heated by the combustion heat in the combustion zone 3.

That is, a hydrocarbon gas such as city gas (usually CH ₄ gas) is supplied to the reformer 2 via the desulfurizer 5 (not shown in FIG. 2), reformed into a hydrogen-rich fuel gas, and reformed. The supplied fuel gas is supplied into the fuel cell main body 1. On the other hand, an oxygen-containing gas (usually air) is supplied into the fuel cell main body 1 through another path, and power is generated by supplying these gases. The gas after power generation is discharged to the upper part of the fuel cell main body 1 and diffused and burned in the combustion zone 3 by ignition by an ignition burner or the like, and combustion waste gas (exhaust gas) is released to the outside.

  As shown in FIG. 2, the fuel cell body 1 has a structure in which a plurality of cell stacks 10 to which a plurality of cells (fuel cells) are connected are arranged at an appropriate interval. A manifold 11 is provided at the lower part. That is, the reformed gas (fuel gas) obtained through the reformer 2 is supplied into the cells of each cell stack 10 via the manifold 11 and discharged from the upper portion of the cell stack 10 to the combustion zone 3. It has become so.

  On the other hand, a power generation gas supply pipe 13 extends downward from above between the cell stacks 10, and an oxygen-containing gas (air) for power generation is supplied through the supply pipe 13. That is, the oxygen-containing gas for power generation is supplied between the cells of the cell stack 10 from the lower end of the supply pipe 13 and is discharged to the combustion zone 3 from the upper part between the cell stacks 10. That is, in the combustion zone 3, combustion by diffusion combustion is performed by supplying sufficient oxygen.

  Referring to FIG. 3 showing the structure of the cell stack 10, the cell stack 10 provided on the manifold 11 has a plurality of plate-like and column-like upright cells (fuel cells) 20 that are elongated in the vertical direction. A gas supply pipe 13 for power generation extends downward from above in a space between the plurality of cell stacks 10.

  In each cell 20, a fuel electrode layer 23, a solid electrolyte layer 25, and an oxygen electrode layer 27 are laminated in this order on one surface of the electrode support substrate 21, and the fuel electrode layer is formed on the other surface of the electrode support substrate 21. The interconnector 29 is laminated so as to face the layer 23. The solid electrolyte layer 25 is provided so as to completely cover the fuel electrode layer 23, and the fuel electrode layer 23 and the solid electrolyte layer 25 wrap around to the other surface of the electrode support plate 21. 29 is joined to both ends. A plurality of gas holes 21a communicating with the manifold 11 are formed inside the electrode support plate 21, and the fuel gas (reformed gas) supplied into the manifold 11 passes through the gas holes 21a. It passes through and is discharged into the upper combustion zone 3. That is, power is generated by supplying a fuel gas (reformed gas) to the gas hole 21 a in the cell 20 and supplying an oxygen-containing gas for power generation from the gas supply pipe 13 between the cell stacks 10. It has a structure.

  Adjacent cells 20 are connected by a current collecting member 31, and the interconnector 31 of one cell 20 and the oxygen electrode layer 27 of the other cell 20 are connected by the current collecting member 31. Although not shown in the drawing, power collecting means 31 is connected to the current collecting members 31 located at both ends of the cell stack 10 so that the generated current is taken out.

  In the cell 20 described above, the electrode support substrate 21 needs to be gas permeable in order to allow the fuel gas to permeate to the fuel electrode layer 23, and moreover be conductive to collect current via the interconnector 29. It can be formed from a porous conductive ceramic (or cermet) that satisfies such a requirement.

  The electrode support substrate 21 is preferably composed of an iron group metal component and a specific rare earth oxide in order to be manufactured by simultaneous firing with the fuel electrode layer 23 and the solid electrolyte layer 25, and has a required gas permeability. Therefore, the open porosity is preferably 30% or more, particularly 35 to 50%, and the conductivity is preferably 300 S / cm or more, particularly 440 C / cm or more.

The fuel electrode layer 23 can be formed of a porous conductive ceramic, for example, ZrO ₂ (referred to as stabilized zirconia) in which a rare earth element is dissolved, and Ni and / or NiO.

The solid electrolyte layer 25 has a function as an electrolyte for bridging electrons between the electrodes, and at the same time needs to have a gas barrier property in order to prevent leakage between fuel gas and air. In general, it is formed from ZrO ₂ in which ₃ to 15 mol% of a rare earth element is dissolved.

The oxygen electrode layer 27 can be formed of a conductive ceramic made of a so-called ABO ₃ type perovskite oxide. The oxygen electrode layer 27 is required to have gas permeability, and preferably has an open porosity of 20% or more, particularly 30 to 50%.

The interconnector 29 can be formed from a conductive ceramic. However, since it is in contact with hydrogen gas (fuel gas) and oxygen-containing gas (air), the interconnector 29 must have reduction resistance and oxidation resistance. Therefore, lanthanum chromite-based perovskite oxides (LaCrO ₃ -based oxides) are preferably used. The interconnect 29 must be dense to prevent leakage of fuel gas passing through the gas holes 21a formed in the electrode support substrate 21 and air flowing outside the electrode support substrate 21, and is 93% or more In particular, it is desirable to have a relative density of 95% or more.

  The current collecting member 31 can be composed of a member having an appropriate shape formed from a metal or alloy having elasticity, or a member obtained by adding a required surface treatment to a felt made of metal fiber or alloy fiber.

That is, in a state where the cell 20 as described above is heated to a predetermined operating temperature (about 700 to 1000 ° C.), an oxygen-containing gas for power generation is caused to flow from the supply pipe 13, and fuel gas (hydrogen) is supplied to the gas holes 21a. When flowing, in the oxygen electrode layer 27,
1 / 2O ₂ + 2e ⁻ → O ²⁻ (solid electrolyte)
The electrode reaction occurs, and in the fuel electrode layer 23,
O ²⁻ (solid electrolyte) + H ₂ → H ₂ O + 2e ⁻
As a result, electric power is generated.

  The structure of the cell 20 is not limited to the example described above. For example, the electrode support plate 21 can be a fuel electrode, and the positional relationship between the fuel electrode layer 23 and the oxygen electrode layer 27 is reversed. It is also possible to provide a structure in which oxygen-containing gas (air) for power generation is supplied to the gas holes 21 a and fuel gas (reformed gas) is supplied between the cell stacks 20.

By the way, in order to generate power using the fuel cell structure as described above, as described above, a hydrocarbon gas typified by city gas is used as a raw fuel as a fuel source. Is reformed into hydrogen-rich fuel gas by a steam reforming reaction and supplied to the fuel cell body 1 through the reformer 2. This steam reforming reaction has the following formula:
CH ₄ + H ₂ O → 3H ₂ + CO
An endothermic reaction represented by Therefore, it is necessary to maintain the reforming catalyst in the reformer 2 at a temperature at which the reforming reaction is started and maintained. It is also necessary to heat the cell 20 to the operating temperature. Therefore, in order to perform such heating without using a special heating source, a combustion zone 3 is provided in the upper part of the fuel cell main body 1, and the combustion zone 3 is provided between the reformer 2 and the fuel ionization main body 1. By arranging, the combustion in the combustion zone 3 is used, but in the present invention, the catalyst is rapidly heated to the steam reforming reaction temperature or higher without using the partial oxidation reaction that is an exothermic reaction, In order to prevent carbon deposition due to thermal decomposition of hydrocarbon gas, the structure of the reformer 2 is as follows, and startup and steady operation are performed.

(Structure of reformer 2)
In the present invention, as shown in FIG. 2, the reformer 2 is disposed so as to be positioned over the entire upper portion of the fuel cell main body 1 (cell stack 10) with the combustion zone 3 interposed therebetween. That is, the entire reformer 2 is heated by the combustion in the combustion zone 3.

  The reformer 2 has a cylindrical shape and is divided into an upper catalyst storage chamber 40 and a lower vaporization chamber 41, and one end (gas supply side) of the catalyst storage chamber 40 has a gas. A mixing chamber 43 is formed, and a gas supply pipe 45 for supplying the raw fuel gas to be reformed is connected to the gas mixing chamber 43. An exhaust pipe 47 for discharging the reformed gas is connected to the other end of the catalyst storage chamber 40, and the exhaust pipe 47 communicates with the manifold 11 of the fuel cell main body 1.

  A steam reforming catalyst 49 is accommodated in the catalyst accommodating chamber 40, and the catalyst accommodating chamber 40 and the gas mixing chamber 43 are partitioned by a partition wall 50 such as a mesh so that the accommodated catalyst 49 does not leak. Has been. Further, the gas mixing chamber 43 and the gas supply side portion of the vaporizing chamber 41 are also partitioned by a partition wall 51 such as a mesh so that water vapor flows.

  A water supply pipe 53 is connected to the gas discharge side portion of the vaporizing chamber 41 so that water is supplied into the vaporizing chamber 41.

In addition, as the steam reforming catalyst 49 accommodated in the catalyst accommodating chamber 40, a known catalyst is used, and for example, a base metal catalyst such as a Ni catalyst or a noble metal catalyst such as Ru or Pt is used. In the present invention, a base metal catalyst is particularly suitable. That is, the noble metal catalyst usually has high oxidation activity, and the reforming reaction start temperature when passing through hydrocarbon gas is about 250 to 300 ° C., but the base metal catalyst such as Ni catalyst has low oxidation activity, The reaction start temperature is as high as about 350 ° C. Therefore, as will be described later, when starting operation is performed by flowing an oxygen-containing gas (starting oxygen-containing gas) and hydrocarbon gas, in order to avoid the inconvenience that the reforming reaction starts during this starting operation. This is because it is advantageous to use a base metal catalyst having a high reforming start temperature. That is, the reforming reaction by supplying oxygen is represented by the following formula:
CH ₄ + 1 / 2O ₂ → 2H ₂ + CO
This is an exothermic reaction represented by Therefore, due to rapid temperature rise and lack of oxygen, carbon is likely to precipitate due to thermal decomposition of hydrocarbon gas. To prevent such partial oxidation reaction with certainty, a base metal catalyst such as Ni catalyst is used. It is advantageous to use it.

  The vaporizing chamber 41 may have any structure as long as it easily vaporizes water and smoothly supplies water vapor to the catalyst housing chamber 40 via the gas mixing chamber 43. For example, the vaporization chamber 41 may be filled with heat-resistant ceramic particles having a high heat capacity.

(Start-up operation)
In order to operate the fuel cell structure and generate electric power, steam is supplied to the reformer 2 and at the same time, the reforming catalyst 49 reaches a predetermined reforming reaction start temperature and the cell 20 has a predetermined operating temperature. Therefore, the start-up operation is performed prior to the steady operation in which power generation is continuously performed.

  In the present invention, in this start-up operation, the oxygen-containing gas for power generation is supplied between the cell stacks 10 and at the same time, the hydrocarbon gas and the oxygen-containing gas (starting oxygen-containing gas) as raw fuel from the gas supply pipe 45 described above. And supply a mixed gas. That is, the mixed gas passes through the reformer 2 and is supplied from the exhaust pipe 47 to the manifold 11 of the fuel cell main body 1. At this stage, no steam is supplied, and the reforming catalyst 49 also has a predetermined temperature. Therefore, the hydrocarbon as the raw fuel is not reformed and is supplied to the fuel cell main body 1 as it is.

  That is, an oxygen-containing gas for power generation and a mixed gas containing hydrocarbon gas are supplied to the combustion zone 3 in the upper part of the fuel cell body 1 and ignited to burn in the combustion zone 3, and the combustion The reformer 2 and the cell 20 are heated by heat. The combustion waste gas generated by the combustion in the combustion zone 3 is released to the outside. In this case, since the oxygen-containing gas is mixed with the mixed gas supplied to the combustion zone 3 together with the oxygen-containing gas for power generation, the energy required for ignition may be low.

  When performing the start-up operation as described above, since the vaporization chamber 41 is interposed between the catalyst storage chamber 40 and the combustion zone 3, the reforming catalyst 49 in the catalyst storage chamber 40 is rapidly heated, It is effectively prevented that the temperature is raised to the reaction start temperature or higher at a stretch in a state where is not supplied.

The starting oxygen-containing gas is a hydrocarbon gas in such an amount that the mixed molar ratio (O ₂ / C) of oxygen (O ₂ ) and hydrocarbon (C) is in the range of 0.5 to 1.0. It is preferable to be mixed with. For example, when the supply amount of the start-up oxygen-containing gas is less than the above range (or when the start-up operation is performed by supplying only the hydrocarbon gas without supplying the start-up oxygen-containing gas), the reforming catalyst 49 When the temperature of the catalyst is raised above the oxidation start reaction temperature, the amount of oxygen that reacts with the hydrocarbon on the reforming catalyst 49 is insufficient, resulting in thermal decomposition of the hydrocarbon, and There is a risk of occurrence. Further, when the supply amount of the oxygen-containing gas for start-up is larger than the above range, when the temperature of the reforming catalyst 49 is raised to the oxidation start reaction temperature or more, complete combustion occurs, and reforming occurs. There is a risk that the temperature of the reformer 2 will rise at a stretch, and the reformer 2 will be damaged. Moreover, since it is complete combustion, there is a risk of backfire that burns in the pipe from the inside of the reformer. That is, in the present invention, even when the temperature of the reforming catalyst 49 is raised to the oxidation start reaction temperature or more by supplying a predetermined amount of the starting oxygen-containing gas, the above disadvantages are avoided. It can be effectively avoided. Further, when the starting oxygen-containing gas is supplied in such an amount, the generation of carbon due to the thermal decomposition of hydrocarbons in the vicinity of the combustion zone 3 can be effectively suppressed.

(Steady operation)
In the present invention, when the temperature of the vaporizing chamber 41 reaches a temperature at which water vapor can be generated by the startup operation, the supply of the oxygen-containing gas for power generation is continued as it is and the supply of the oxygen-containing gas for startup is stopped. Then, only the hydrocarbon gas is supplied from the gas supply pipe 45 and water is supplied from the water supply pipe 53 to perform steady operation. That is, when the supply of the starting oxygen-containing gas is continued as it is, a partial oxidation reaction that is incomplete combustion occurs due to the temperature rise of the reforming catalyst 49, and when the partial oxidation reaction is continued, the reformer 2 is brought into the interior. Heating from the outside may cause damage to the reformer 2 and the reforming catalyst 49 due to excessive temperature rise.

  Note that the water vapor generating temperature is a temperature at which water supplied from the water supply pipe 53 can vaporize in the vaporizing chamber 41 to generate water vapor, and if the temperature in the vaporizing chamber 41 is 100 ° C. or higher. Although it is possible to prevent condensation of water vapor after vaporization at about 100 ° C., it is generally difficult to vaporize the total amount of water supplied from the water pipe 53. When the inside of the chamber 41 reaches about 200 to 300 ° C., it is preferable to start the steady operation by stopping the supply of the oxygen-containing gas for starting. In this case, the temperature of the reforming catalyst 49 is preferably lower than the reforming reaction start temperature, and therefore the start timing of steady operation is set according to the reforming reaction start temperature of the reforming catalyst 49 to be used. It is good to do. (If the start-up oxygen-containing gas is supplied even when the reforming catalyst 49 is heated to a temperature higher than the reforming reaction start temperature, the reformer 2 and the reforming catalyst 49 may be damaged by an excessive temperature rise due to a partial oxidation reaction. There is a risk of inviting.)

  The start timing of the steady operation can be adjusted by monitoring the temperature in the vaporization chamber 41 with an appropriate temperature sensor, and the steady operation is started when the predetermined steam generation temperature is reached. do it. Further, the amount of water supplied from the water supply pipe 53 may be set in accordance with the amount of hydrocarbon gas supplied so that the steam reforming reaction described above can occur effectively.

  By such steady operation, when the reforming catalyst 49 reaches a predetermined reforming reaction start temperature (350 ° C. or higher) due to combustion in the combustion zone 3, the steam reforming reaction described above starts, and reforming occurs. The gas discharged to the exhaust pipe 47 through the vessel 2 becomes a hydrogen-rich fuel gas, supplied from the manifold 11 into the fuel cell main body 1 (inside the cell 20), and discharged from the fuel cell main body 1 to the combustion zone 3 Is done. Furthermore, when the temperature of the cell 20 reaches the power generation temperature (600 to 1000 ° C.), power generation is started by the electrode reaction described above.

  The steam reforming reaction in the reforming catalyst 49 is an endothermic reaction. If this reaction is continued, the temperature is lowered. However, according to the steady operation as described above, the reforming is performed by the combustion heat in the combustion zone 3. The temperature of the catalyst 49 can be maintained, and the steam reforming reaction can be effectively continued. Moreover, the temperature in the gas mixing chamber 43 located on the gas supply side of the reformer 2 can be maintained at 300 to 600 ° C. by the heat of vaporization, and the temperature of the gas mixing chamber 43 without the reforming catalyst is increased. Hydrolysis of hydrocarbons can be effectively suppressed.

  In the above example, the gas passing through the reformer 2 is supplied from the manifold 11 to the inside of the cell 20 (gas hole 21a) through the exhaust pipe 47, and the oxygen-containing gas for power generation is supplied from the supply pipe 13 to the cell. Although the gas is supplied between the stacks 10, as described above, the gas that has passed through the reformer 2 is supplied between the cell stacks 10 according to the structure of the cells 20, and oxygen is contained for power generation. It is also possible to supply gas into the cell 20 (gas hole 21a).

  According to the present invention described above, the start-up operation and the steady operation are performed without using any partial oxidation reaction. However, even if the partial oxidation reaction occurs, it is the maximum that carbon deposition can be effectively suppressed. Is the advantage.

The figure for demonstrating the flow of the gas in the operating method of this invention. The figure which shows schematic structure of the fuel cell structure used for this invention. The figure which shows the schematic structure of the cell stack of the fuel cell main body in the fuel cell structure of FIG. 2 (AA sectional drawing of FIG. 2).

Explanation of symbols

1: Fuel cell body 2: Reformer 3: Combustion zone 41: Vaporization chamber 49: Reforming catalyst 53: Water pipe

Claims (9)

About a fuel cell structure including a fuel cell main body and a reformer in which a reforming catalyst is accommodated, hydrocarbon gas is reformed into hydrogen-rich fuel gas by steam reforming through the reformer, the fuel gas was supplied to the fuel cell body and the fuel gas to generate electricity by supplying an oxygen-containing gas to the fuel cell main body in a different path, is burned gas discharged from the fuel cell body, the in the operating method of the fuel cell structure for discharging the combustion exhaust gas generated by the combustion in the external,
During startup, the hydrocarbon gas a mixed gas of the oxygen-containing gas, the supplies to the fuel cell main body through the reformer, the oxygen-containing gas wherein an oxygen-containing gas in a separate path fuel cell body supplied to, and the mixed gas and the oxygen-containing gas different route is burned is discharged from the fuel cell main body, heating the reformer and the fuel cell main body by this combustion heat,
Temperature of the reformer, after the steam reforming is allowed to start, and at the same time to supply steam to the reformer, and stopping the supply to the reformer of the oxygen-containing gas, said hydrocarbon performs steam reforming by the gas passing the reformer, and the oxygen-containing gas in a separate path and the fuel gas reformed hydrogen-rich to generate electricity is supplied to the fuel cell body, the It said oxygen-containing gas and is burned the fuel gas, a method of operating a fuel cell structure, wherein the performing steady operation while discharging the combustion exhaust gas to the outside caused by the combustion is discharged from the fuel cell body.   The operation method according to claim 1, wherein a base metal catalyst or a noble metal catalyst is used as the reforming catalyst.   The operation method according to claim 1, wherein a Ni catalyst is used as the reforming catalyst. The mixed gas of the hydrocarbon gas and the oxygen-containing gas oxygen _{(O 2)} and hydrocarbons (C) and the mixing molar ratio of _(O 2 / C) is in a range of 0.5 to 1.0 The operation method according to any one of claims 1 to 3, wherein the operation method is mixed.   The operating method according to any one of claims 1 to 4, wherein a combustion region of gas discharged from the fuel cell main body is disposed above the fuel cell main body, and the reformer is disposed above the combustion region. The reformer is provided with a reforming catalyst storage chamber for accommodating the reforming catalyst, the lower portion of the reforming catalyst storage chamber, a vaporization chamber in communication with the hydrocarbon gas feed side of the reforming catalyst storage chamber the provided, the hydrocarbon gas supply side of the vaporization chamber is connected to the water pipe on the other side portion Rutotomoni, supplying water to said transmission water pipe, generating steam in the vaporization chamber by the heating by the combustion heat the method of operation according to claim 5 for supplying the allowed and in the reformer the steam is. The combustion in the combustion zone, when the vaporization chamber is heated above a temperature that enables generation steam supply water fed to the water pipe, the water vapor generated in the vaporizing chamber to the reformer The operation method according to claim 6. The temperature of the reforming catalyst in the reformer, when less than the reforming reaction starting temperature, method of operation according to claim 7 for supplying steam to the reformer. Said fuel cell body, the cell stack in which a plurality of cells are connected has a plurality ordered structure suitable intervals, the passed through the reformer gas is supplied into the cell stack, the is discharged through the interior of each cell, the oxygen-containing gas in another path is supplied to the space between the cell stack, the in any one of claims 1 to 8 and is discharged through the outer surface of each cell The driving method described.

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