JP4991087B2 - Fuel cell assembly - Google Patents

Description

The present invention relates to a fuel cell assembly, and more particularly to a fuel cell assembly suitable for use in the construction of such a fuel cell power generation system of the solid electrolyte fuel cell power generation system.

  In recent years, various fuel cells in which a stack of fuel cells is housed in a housing have been proposed as next-generation energy.

Solid electrolyte fuel cell, a fuel cell stack comprising a plurality of solid electrolyte fuel cell is configured by accommodated in the housing, is operated at a temperature of about 1000 ° C..

  As a general hydrogen supply method used as a fuel for power generation, a steam reforming method is used in which hydrogen such as natural gas reacts with steam to generate hydrogen. This reaction is also performed at 500 to 900 ° C. Therefore, there is a problem that it takes a long time to heat the reformer that performs the reforming reaction.

To solve this problem, the fuel reformer of the solid electrolyte fuel cell disposed in a housing that houses the fuel cell stack, the heat generated during power generation by utilizing the steam reforming reaction, Improvement of thermal efficiency is performed (for example, refer patent document 1).

In the polymer electrolyte fuel cell, a fuel method combining partial oxidation exothermic is the reaction for the activation time reduction of the reformer or partial oxidation and steam reforming method (hereinafter, autothermal method) by A reformer that eliminates the need for a heating source by performing reforming has been reported (see, for example, Patent Document 2).
JP-A-8-287937 JP 2001-185196 A

  However, in the system in which the above-described fuel reformer is disposed in the housing, the reforming catalyst is filled in the fuel supply chamber at the top of the power generation chamber, and radiant heat from the power generation chamber and heat transfer of the exhaust gas are used as a heat source. There are problems that the distance from the heat source is increased and it takes time to raise the temperature of the fuel reformer, and that heating to a temperature higher than the power generation temperature is impossible.

  In addition, when the fuel cell output is reduced and the load is low, the amount of heat generated by the power generation reaction is reduced, so that the temperature of the power generation chamber is lowered and the amount of heat necessary for the steam reforming reaction may be insufficient. Furthermore, since an external heating source is required at the time of start-up, there is a problem that the thermal efficiency is lowered.

  In addition, when fuel reforming is always performed by a partial oxidation method or a combination of a partial oxidation method and a steam reforming method, the amount of hydrogen produced is less than that of the steam reforming method, resulting in a decrease in power generation efficiency. There is a problem. That is, the conventional method has a problem that the start-up time is not yet shortened and high power generation efficiency is not sufficiently achieved. For this reason, the present applicant has applied for a fuel cell assembly in which the reformer is accommodated in the housing so as to be exposed to the combustion gas (Japanese Patent Application No. 2003-151455).

  In such a fuel cell assembly, since the reformer is exposed to the combustion gas, the reformer can be heated in a short time, but the reforming catalyst and the reforming catalyst in the vicinity of the reformed gas introduction portion are not provided. Since it is heated to an appropriate temperature or higher, cracking of hydrocarbons in the reformed gas supplied to the reformer is likely to occur, a stable reforming reaction cannot be obtained, and carbon deposition occurs. there were.

  It is an object of the present invention to provide a fuel cell assembly that generates a stable reforming reaction in a reformer.

As a result of studying the above problems, the present inventor does not directly expose the reformed gas introduction part in which the reformed gas enters the reformed gas generation part of the reformer in which the reforming catalyst is accommodated, to the combustion gas. By doing so, it was found that carbon deposition due to cracking of hydrocarbons in the gas to be reformed can be suppressed, and a stable reforming reaction can be obtained, leading to the present invention .

That is, the fuel cell assembly of the present invention, in a housing, a cell stack formed by arranging in a row a plurality of fuel cells of the solid electrolyte, reformer which is disposed above the cell stack And a power generation unit that burns fuel gas that has not been used for power generation of the fuel cell in a region between the cell stack and the reformer. have a reformed gas generator comprising a reforming catalyst for a reformed gas by reforming to produce a fuel gas supplied to the fuel cell, the reforming gas generator, said from the said cell stack The gas stack extends to the outside from the end of the cell stack, and a reformed gas introduction part is provided in the extension region of the reformed gas generation part, and the reformed gas is at one end of the reformer. The reformed gas generation is introduced into the reformed gas introduction section from the section The reformed gas generated in, characterized in that derived from the other end of the reformer.

Target gas, and since when the reforming catalyst near the reformed gas inlet is excessively higher than the predetermined temperature occurs carbon deposition by cracking, reforming near Hiaratameshitsuga scan guide join the club The temperature control of the catalyst is important. In the fuel cell assembly of the present invention, the reformed gas generator extends from the top of the cell stack to the outside of the end of the cell stack, and the reformed gas introduction unit extends into the extension region of the reformed gas generator. In order to control the temperature of the reformed gas introduction part, it is possible to prevent an excessive temperature rise in the vicinity of the reformed gas introduction part. As a result, carbon deposition due to cracking can be prevented, so that adverse effects such as an increase in pressure loss can be prevented, and a stable reforming reaction can be obtained in the reformer.

  In addition, by disposing the reformer in the housing containing the fuel battery cells, it is not necessary to separately provide a heating source necessary for the steam reforming reaction, so that the thermal efficiency can be improved and surplus fuel gas By burning the fuel in the housing, a heat source having a temperature higher than that of the power generation unit of the fuel battery cell can be used as the heating source of the reformer, so that the reformer can be heated quickly. Furthermore, by using a high-temperature heat source, it is possible to sufficiently cover the amount of heat necessary for the steam reforming reaction even during low-load operation where the amount of heat generated by the power generation of the fuel cell is reduced. By placing such a reformer at a predetermined interval from the front end of the cell on the combustion side, deterioration of the reforming pipe member and the reforming catalyst due to excessive temperature rise can be suppressed.

The fuel cell assembly of the present invention, the introduced into the reforming target gas inlet the reformed gas from one end of the front Kiaratame reformer, reforming generated by the reformed gas generator gas, characterized in that it is derived from the other end of the front Kiaratame reformer. In such a fuel cell assembly, a combustion region F for burning fuel gas that has not been used for power generation of the fuel cell is formed in a region between the cell stack and the reformer. Therefore, reformed gas is introduced from one end of the reformer to be reformed gas inlet, the reformed gas generated in the reforming gas generator is derived from the other end of the reformer With the structure, the heat transfer surface from the combustion region F can be increased, and a sufficient amount of heat necessary for the reforming reaction can be supplied. In addition, it is possible to sufficiently ensure the contact time between the reformed gas (a collective term for hydrocarbons necessary for the reforming reaction and oxygen sources such as steam) and the reforming catalyst.

The fuel cell assembly of the present invention, the cell stack is in communication with the fuel gas chamber which is disposed below the cell stack, the reformed gas generated in the reformer, The fuel gas chamber is supplied through a reformed gas supply path. In such a fuel cell assembly, the cell stack that communicates with the fuel gas chamber which is disposed below the cell stack, so that it can uniformly supply the reformed gas to be introduced from the reformer into a plurality of cells become. In addition, the reformed gas generated in the reformer is supplied to the fuel gas chamber via the reformed gas supply path, so that the reformed gas receives radiant heat from the cell due to the power generation reaction, and thus the temperature is higher. Thus, the reformed gas can be supplied to the cell, and a decrease in output due to a decrease in cell temperature can be prevented.

The fuel cell assembly of the present invention, wherein the reformer, the reformed gas preheating section in the direction of flow of the gas to be reformed, the reformed gas generator, reforming gas preheating section is found in this order It is characterized by being. In such a fuel cell assembly, the temperature of the reforming catalyst can be maintained at an appropriate temperature by preheating the gas to be reformed to a predetermined temperature and then introducing it into the reformed gas generation section, which is effective for carbon deposition. Can be suppressed. In addition, by setting the reformed gas at a higher temperature than the reforming temperature, it is possible to prevent a decrease in output due to a decrease in the temperature of the fuel cell .

Furthermore, the fuel cell assembly of the present invention, in the housing, Rutotomoni have juxtaposed a plurality of the power generation units, the power generating unit, the said connected to the reformer wherein the reformed gas reformed has to be reformed gas supply passage for supplying the vessel, the arrangement position of the reformed gas supply passage of the object to be reformed gas supply passage and the other of said power generation unit of the adjacent one of said power generation unit It arrange | positions so that it may become an other side , It is characterized by the above-mentioned.

  Since the gas to be reformed is generally supplied from the outside to the reformer through the side of the cell stack, the temperature in the vicinity of the gas to be reformed supply path is lower than the ambient temperature. The temperature range that is lowered by the quality gas supply path is distributed to the opposing positions via the power generation unit, is not biased to one side, and there is no temperature gradient in the housing, thereby reducing the temperature difference of the cell stack. Variations in power generation performance of fuel cells can be reduced. Moreover, by producing a plurality of power generation units of the same type and reversing the arrangement direction, the fuel cell assembly of the present invention can be easily produced, and the adjacent power generation in which the arrangement direction is reversed By electrically connecting the same side of the unit cell stacks, the fuel cells can be easily connected in series and a high voltage can be obtained.

  According to the fuel cell assembly of the present invention, by disposing the reformer in the housing containing the fuel cell, it is not necessary to separately provide a heating source necessary for the steam reforming reaction, and the thermal efficiency is improved. In addition, by burning excess fuel gas in the housing, a heat source having a temperature higher than that of the power generation unit of the fuel cell can be used as a heating source of the reformer, so that the reformer can be heated quickly. can do. In addition, by using a high-temperature heat source, the amount of heat necessary for the steam reforming reaction can be sufficiently provided even during low-load operation where the amount of heat generated by the power generation of the fuel battery cell is reduced.

Further, the reformed gas generator extends from the cell stack to the outside of the end of the cell stack, and the reformed gas generator is modified by providing the reformed gas introduction section in the extending region of the reformed gas generator. In order to control the temperature of the reformed gas introduction part of the quality device, it is possible to prevent carbon deposition by preventing excessive temperature rise in the vicinity of the reformed gas introduction part. Further, the gas to be reformed is introduced from one end of the reformer into the gas to be reformed introduction section, and the reformed gas generated in the reformed gas generation section is led out from the other end of the reformer. Thus, a sufficient amount of heat necessary for the reforming reaction can be supplied, and a sufficient contact time between the reformed gas and the reforming catalyst can be secured.

  The fuel cell assembly of the present invention will be described in detail below with reference to the drawings.

  Referring to FIGS. 1, 2 and 3, the illustrated fuel cell assembly includes a housing 2 having a substantially rectangular parallelepiped shape. The six wall surfaces of the housing 2 are heat insulating walls formed of an appropriate heat insulating material, that is, an upper heat insulating wall 4, a lower heat insulating wall 6, a right heat insulating wall 8, a left heat insulating wall 9, a front heat insulating wall 10, and a rear heat insulating wall. 11 is disposed. A power generation / combustion chamber 12 is defined in the housing 2.

  The front heat insulation wall and / or the rear heat insulation wall are detachably or detachably mounted, and the power generation / combustion chamber 12 can be accessed by detaching or opening the front heat insulation wall and / or the rear heat insulation wall. If desired, an outer wall, which may be made of a metal plate, can be disposed on the outer surface of each heat insulating wall.

  An air chamber (gas chamber) 16 is disposed at the upper end of the housing 2. The air chamber 16 is defined in a rectangular parallelepiped case 17 having a relatively small vertical dimension. The air chamber 16 communicates with an air introduction pipe (gas supply means) 22 for sending air (oxygen-containing gas) toward the power generation / combustion chamber. There are a plurality of air introduction pipes 22 and the shape thereof may be a cylinder or a hollow plate structure. The air introduction pipe 22 is disposed between the cell stacks described later, and has an opening at the lower end portion of the cell, and air is ejected from the opening portion. The air introduction tube 22 is preferably made of a material having high heat resistance such as ceramics.

  In the fuel cell assembly of the present invention, the air chamber 16 is provided with a low-temperature gas supply means including a low-temperature gas supply pipe 18. The low-temperature gas supply pipe 18 penetrates the upper heat insulating wall 4 and is externally provided. It is extended to.

  The low-temperature gas supply pipe 18 supplies the same type of gas as that supplied into the air chamber 16, that is, low-temperature air, into the air chamber 16. The air supplied through the low-temperature gas supply pipe 18 is The temperature needs to be lower than the temperature of the preheated air. In particular, about room temperature is desirable.

  As shown in FIG. 2, the low temperature gas supply pipe 18 is connected to a position of the air chamber 16 that cools the power generation units 56a, 56b, 56c, and 56d, that is, the central portion of the fuel cell assembly. In other words, the air introduction pipe 22 disposed between the power generation units 56a, 56b, 56c, and 56d has a low temperature so as to open at the position of the opposing case 17 side plate with respect to the center of the opening assembly to the case 17 side plate. A gas supply pipe 18 is provided.

  A heat exchanger 24 having a flat plate shape as a whole is disposed on both sides of the housing 2, more specifically, inside the right heat insulating wall 8 and inside the left heat insulating wall 9. Each of the heat exchangers 24 is constituted by a case 26 having a hollow flat plate shape extending substantially vertically.

  A partition plate 28 located in the middle in the lateral direction is disposed in the case 26, and the inside of the case 26 is partitioned into a discharge path 30 positioned on the inner side and an inflow path 32 positioned on the outer side. Three partition walls 34 and 36 are arranged in the discharge path 30 at intervals in the vertical direction. More specifically, in the discharge passage 30, the front edge is located rearwardly away from the front wall (not shown) of the case 26, but the rear edge is the rear wall (not shown) of the case 26. And a partition wall 36 whose front edge is connected to the front wall of the case 26 but whose rear edge is spaced forward from the rear wall of the case 26. Are alternately arranged, and thus the combustion gas discharge passage 30 is zigzag-shaped. If desired, a form other than the zigzag flow path may be used.

  Similarly, the three partition walls 38 and 40, that is, the front edges thereof are also spaced apart from the front wall (not shown) of the case 26 in the inflow path 32 with a space in the vertical direction. The rear wall is connected to the rear wall (not shown) of the case 26, and the front edge of the partition wall 38 is connected to the front wall of the case 26. The partition walls 40 spaced apart from the front are alternately arranged, and thus the inflow passage 32 is also zigzag-shaped. If desired, a form other than the zigzag flow path may be used.

  A discharge opening 42 is formed at the upper end of the inner wall of the case 26, and the discharge path 30 is communicated with the power generation / combustion chamber 12 through the discharge opening 42. In the illustrated embodiment, a heat insulating member 44 is disposed between each of the heat exchangers 24 and the power generation / combustion chamber 12, and the upper end of the heat insulating member 44 is substantially the same as the lower edge of the discharge opening 42. The discharge opening 42 is communicated with the power generation / combustion chamber 12 through a space remaining above the heat insulating member 44.

  An inflow opening 48 is formed on the outer side of the upper wall of the case 26, and the inflow path 32 is communicated with the air chamber 16 through the inflow opening 48. The heat exchanger 24 and the inflow opening 48 constitute heated gas supply means. A double cylinder 50 (only the upper end portion thereof is shown in FIG. 1) extending in the vertical direction is disposed behind each of the heat exchangers 24. The double cylinder 50 is an outer cylinder. The member 52 and the inner cylinder member 54 are configured. The lower end of the discharge path 30 is connected to the lower end of the discharge path defined between the outer cylinder member 52 and the inner cylinder member 54, and the lower end of the inflow path 32 is defined in the inner cylinder member 54. Connected to the inflow channel.

  Thus, the configuration of the fuel cell assembly shown in the drawing is substantially the same as the fuel cell assembly disclosed in the specification and drawings of Japanese Patent Application No. 2003-295790 filed by the present applicant. Therefore, the details of the configuration described above are left to the specification and drawings of Japanese Patent Application No. 2003-295790, and the description thereof is omitted in this specification.

  Four power generation units 56a, 56b, 56c and 56d are arranged in the lower part of the above-described power generation / combustion chamber. The power generation units 56a, 56b, 56c, and 56d are respectively positioned between the air introduction pipes 22 described above. In other words, the air introduction pipe 22 is disposed between the power generation units 56a, 56b, 56c and 56d. 3 together with FIGS. 1 and 2, the power generation unit 56a includes a rectangular parallelepiped fuel gas manifold 58a extending in the front-rear direction (a direction perpendicular to the paper surface in FIG. 1).

  A cell stack 60a is mounted on the upper surface of the fuel gas manifold 58a that defines the fuel gas chamber. The cell stack 60a is configured by arranging a plurality of plate-like and column-like upright cells 62 extending vertically in the vertical direction in the longitudinal direction of the fuel gas manifold 58a (that is, the front-rear direction in FIG. 1). As clearly shown in FIG. 5, each cell 62 includes an electrode support substrate 64, a fuel electrode layer 66 that is an inner electrode layer, a solid electrolyte layer 68, an oxygen electrode layer 70 that is an outer electrode layer, and an interconnector 72. Has been.

  The electrode support substrate 64 is a plate-like piece that is elongated in the vertical direction, and has both flat surfaces and both sides of a semicircular shape. The electrode support substrate 64 is formed with a plurality (six in the illustrated example) of fuel gas passages 74 penetrating the electrode support substrate 64 in the vertical direction. Each of the electrode support substrates 64 is bonded to the upper wall of the fuel gas manifold 58a by, for example, a ceramic adhesive having excellent heat resistance.

  On the upper wall of the fuel gas manifold 58a, a plurality of slits (not shown) extending in the left-right direction are formed at intervals in the direction perpendicular to the paper surface in FIG. A fuel gas passage 74 is communicated with each of the slits and thus with the fuel gas chamber.

  The interconnector 72 is disposed on one side of the electrode support substrate 64 (upper surface in the cell stack 60a in FIG. 5). The fuel electrode layer 66 is disposed on the other surface (the lower surface in the cell stack 60a of FIG. 5) and both side surfaces of the electrode support substrate 64, and both ends thereof are joined to both ends of the interconnector 72. The solid electrolyte layer 68 is disposed so as to cover the entire fuel electrode layer 66, and both ends thereof are joined to both ends of the interconnector 72. The oxygen electrode layer 70 is disposed on the main part of the solid electrolyte layer 68, that is, on the portion covering the other surface of the electrode support substrate 64, and is positioned to face the interconnector 72 with the electrode support substrate plate 64 interposed therebetween. Yes.

  A current collecting member 76 is disposed between adjacent cells 62 in the cell stack 60a, and connects the interconnector 72 of one cell 62 and the oxygen electrode layer 70 of the other cell 62. Current collecting members 76 are disposed on both ends of the cell stack 60a, that is, on one side and the other side of the cell 62 positioned at the upper end and the lower end in FIG. The power extraction means (not shown) is connected to the final power members 76 located at both ends of the cell stack 60a, and the power extraction means is connected to the front heat insulating wall 10 (not shown) and / or the rear of the housing 2. It extends outside the housing 2 through heat insulation 11 (not shown). If desired, the cell stacks 60a, 60b, 60c and 60d are connected in series with each other by appropriate connection means instead of disposing the power extraction means in each of the cell stacks 60a, 60b, 60c and 60d. Common power extraction means may be provided for the cell stacks 60a, 60b, 60c and 60d.

  The cell 62 will be described in more detail. The cell 62 has a plate shape and a column shape, and the electrode support substrate 64 is gas permeable so as to allow the fuel gas to permeate to the fuel electrode layer 66. In order to collect current through the electrode, it is required to be conductive, and it can be formed from a porous conductive ceramic (or cermet) that satisfies such a requirement.

In order to manufacture the electrode support substrate 64 by simultaneous firing with the fuel electrode layer 66 and / or the solid electrolyte layer 70, it is preferable to form the electrode support substrate 64 from an iron group metal component and a specific rare earth oxide. In order to provide the required gas permeability, it is preferred that the open porosity is in the range of 30% or more, in particular 35 to 50%, and the conductivity is also 300 S / cm or more, in particular 440 S / cm or more. Is preferred.

The fuel electrode layer 66 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 68 has a function as an electrolyte for bridging electrons between 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 70 can be formed of a conductive ceramic made of a so-called ABO ₃ type perovskite oxide. The oxygen electrode layer 70 is required to have gas permeability, and preferably has an open porosity of 20% or more, particularly 30 to 50%.

Although the interconnector 72 can be formed from a conductive ceramic, it needs to have a reduction resistance and an oxidation resistance in order to come into contact with a fuel gas and air that may be hydrogen gas. A perovskite oxide (LaCrO ₃ oxide) is preferably used. The interconnect 72 must be dense in order to prevent leakage of fuel gas passing through the fuel gas passages 74 formed in the electrode support substrate 64 and air flowing outside the electrode support substrate 64, particularly 93% or more, It is desirable to have a relative density of 95% or higher.

  The current collecting member 76 can be composed of a member having an appropriate shape formed of 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.

  Continuing the description with reference to FIGS. 1 to 4, the power generation unit 56a also includes a reformer 78a that is preferably a rectangular parallelepiped shape (or cylindrical shape) extending in the front-rear direction above the cell stack 60a. is doing. That is, the reformer 78a is disposed above the cell stack 60a at a predetermined interval from the tip of the cell 62 and in the cell arrangement direction. By housing the reformer 78a in the housing 2 and the power generation / combustion chamber 12, the fuel cell assembly can be greatly reduced in size.

  The length h in the cell height direction of the reformer 78a is shorter than the length L in the cell arrangement direction. By reducing the length h in the cell height direction of the reformer 78a, the temperature gradient between the bottom surface (side exposed to the combustion flame) and the top surface (exhaust port side) of the reformer 78a can be reduced. The reformed gas composition in the reformer 78a is close to the equilibrium composition, and a stable reforming reaction can be achieved. Further, the heat transfer surface of the reformer 78a can be increased, the amount of heat necessary for the reforming reaction can be supplied, and sufficient contact time between the reformed gas and the reforming catalyst can be ensured. it can.

  The length L in the cell arrangement direction of the reformer 78a is about 2 to 15 times the length h in the cell height direction, so that the gas to be reformed and reforming required for the reforming reaction From the viewpoint of ensuring the contact time of the catalyst for the catalyst. When the reformer 78a has a cylindrical shape, the length h in the cell height direction can be read as the diameter of the cylinder.

The reformer 78a is configured such that the gas to be reformed is introduced from one end of the reformer 78a and the reformed hydrogen-rich fuel gas is derived from the other end.

  That is, a plurality of fuel cells 62 are erected on the manifold 58a, a fuel gas supply pipe 80a from the reformer 78a is provided on the cell arrangement direction side of the cell stack 60a, and one end of the reformed gas supply path 80a is provided. Is connected to the front end face of the reformer 78a.

  The other end side of the fuel gas supply pipe 80a extends downward through the cell arrangement direction side, then curves and extends rearward, and the other end of the fuel gas supply pipe 80a is connected to the front surface of the fuel gas manifold 58a. Yes. One end of a reformed gas supply path 82a is connected to the rear surface of the reformer 78a. The to-be-reformed gas supply path 82 a extends downward from the reformer 78 a via the cell arrangement direction side, and extends under the housing 2 to the outside of the housing 2.

  By providing the fuel gas supply pipe 80a through the side of the cell stack 60a, the reformed fuel gas receives radiant heat from the cell stack 60a due to the power generation reaction, so that the higher temperature fuel gas is transferred to the cell 62. Therefore, it is possible to prevent a decrease in output due to a decrease in cell temperature due to a low temperature fuel gas supply. The fuel gas supply pipe 80a is connected to the front surface of the fuel gas manifold 58a in FIGS. 1 to 4, but the same effect can be obtained by connecting to the side surface of the fuel gas manifold 58a.

  The to-be-reformed gas supply path 82a is connected to a to-be-reformed gas supply source (not shown) which may be a hydrocarbon gas such as city gas, and is connected to the reformer 78a through the to-be-reformed gas supply path 82a. A gas to be reformed is supplied.

In the reformer 78a, a reformed gas preheating unit 78a1, a reforming unit (hereinafter referred to as a reformed gas generating unit) 78a2, and a reformed gas preheating unit 78a3 are sequentially formed in the direction in which the reformed gas flows . The reformed gas preheating section 78a1 has a space without a filler to reduce pressure loss, or a plurality of partitions parallel to the gas flow direction in order to transmit more heat to the reformed gas. A reforming gas generation unit 78a2 is provided with an appropriate reforming catalyst for reforming the gas to be reformed into a hydrogen-rich fuel gas. The preheating part 78a3 has the same structure as the reformed gas preheating part.

  Further, by providing the reformed gas supply path 82a and the fuel gas supply pipe 80a through the side of the cell stack 60a, for example, by optimizing the surface area and the like, the reformed gas and the reformed gas are improved. A reformed gas preheating part for preheating gas to a desired temperature and a reformed gas preheating part can be provided.

The reforming catalyst in the reformed gas generator 78a2 is mainly classified into a noble metal catalyst and a base metal catalyst, and either or a mixture of these may be used. The base metal catalyst is preferably formed by supporting a transition metal such as Ni on the surface of spherical Al ₂ O ₃ , and the noble metal catalyst is similarly configured by supporting Ru on the surface of spherical Al ₂ O ₃ . A third component may be added.

In the fuel cell assembly of the present invention, as shown in FIG. 4 (b), the reformed gas generator 78a2 of the reformer 78a extends outward from the end of the cell stack 60a (predetermined distance). m) A reformed gas introduction part 78a0 is provided in the extending region of the reformed gas generation part 78a2 . That is, the to-be-reformed gas preheating part 78a1 into which the to-be-reformed gas flows from the to-be-reformed gas supply path 82a and the to-be-reformed gas introduction part 78a0 of the reformed gas generating part 78a2 are not exposed directly to the combustion gas. It is configured.

The reformed gas introduction part 78a0 of the reformer 78a is configured not to be directly exposed to the combustion gas, so that heat transfer from a portion directly exposed to the combustion gas and heat of the reformed gas Transmission and heat absorption due to the reforming reaction can be balanced to prevent overheating of the catalyst in the vicinity of the reformed gas introduction part 78a0 and to prevent carbon deposition. The separation distance m is preferably set so that the temperature of the reformed gas introduction part is 400 ° C. or less from the viewpoint that the hydrocarbons are suppressed to a temperature that causes cracking or less.

  In the illustrated embodiment, the reformer 78a is connected to the fuel gas manifold 58a via the fuel gas supply pipe 80a, and is thereby held in a required position. If necessary, the reformer 78a is shown by a two-dot chain line in FIG. As shown in the figure, for example, an appropriate support member 84a can be provided between the lower surface of the reformed gas supply path 82a and the upper surface or rear surface of the rear end portion of the fuel gas manifold 58a.

  Referring to FIG. 3, the power generation unit 56c is substantially the same as the power generation unit 56a described above, and the power generation units 56b and 56d are disposed in the front-rear direction opposite to the power generation units 56a and 56c. Fuel gas supply pipes (not shown) connecting the mass devices 78b and 78d and the fuel gas manifolds 58b and 58d are arranged on the rear side, and the reformed gas supply paths 82b and 82d extend downward from the reformer. , Extending under the housing 2 and out of the housing 2.

  That is, in the fuel cell assembly of the present invention, as shown in FIG. 3, the fuel gas supply pipes 80a, 80b, 80c and 80d are arranged so as to face the periphery of the assembly of the cell stacks 60a to 60d. Yes. In other words, the fuel gas supply pipes 80a, 80b, 80c, and 80d are alternately arranged on the opposite side surfaces (side surfaces in the arrangement direction of the fuel cells 62) of the assembly of the cell stacks 60a to 60d. . Further, the reformed gas supply passages 82a, 82b, 82c and 82d for the fuel gas to be reformed are also alternately arranged on the opposite side surfaces of the assembly of the cell stacks 60a to 60d. The reformed gas supply paths 82a, 82b, 82c and 82d are alternately arranged with the fuel gas supply pipes 80a, 80b, 80c and 80d on one and the other side surfaces.

  In such a fuel cell assembly, the reformed gas introduced into the reformers 78a, 78b, 78c and 78d through the reformed gas supply passages 82a, 82b, 82c and 82d is usually from the outside of the housing 2. Since the temperature near the reformed gas supply pipe is lowered, the reformed gas supply paths 82a, 82b, 82c and 82d are arranged on the opposite side surfaces of the assembly of the cell stacks 60a to 60d. By arranging them alternately, the temperature difference around the assembly of the cell stacks 60a to 60d can be reduced, and the variation in the power generation performance of the fuel cells can be reduced.

  Further, since the fuel gas supply pipes 80a, 80b, 80c and 80d for supplying the fuel gas are arranged so as to face the periphery of the assembly of the cell stacks 60a to 60d, the assembly of the cell stacks 60a to 60d. The temperature difference in the periphery of the

  In the fuel cell assembly as described above, the gas to be reformed is supplied to the reformers 78a, 78b, 78c and 78d through the gas to be reformed supply paths 82a, 82b, 82c and 82d, and the reformer 78a. , 78b, 78c, and 78d, the fuel gas is defined in the fuel gas manifolds 58a, 58b, 58c, and 58d through the fuel gas supply pipes 80a, 80b, 80c, and 80d. To the chamber and then to the cell stacks 60a, 60b, 60c and 60d.

In each of the cell stacks 60a, 60b, 60c and 60d, at the oxygen electrode,
1 / 2O ₂ + 2e ⁻ → O ²⁻ (solid electrolyte)
The electrode reaction of
O ²⁻ (solid electrolyte) + H ₂ → H ₂ O + 2e ⁻
The electrode reaction is generated and power is generated.

  Fuel gas and air that have flown upward from the cell stacks 60a, 60b, 60c and 60d without being used for power generation are ignited by an ignition means (not shown) disposed in the power generation / combustion chamber 12 at the time of startup. It is ignited and burned. As is well known, the power generation / combustion chamber 12 has a high temperature of, for example, about 1000 ° C. due to power generation in the cell stacks 60a, 60b, 60c and 60d, and also due to combustion of fuel gas and air. The reformers 78a, 78b, 78c and 78d are disposed in the power generation / combustion chamber 12, and are positioned immediately above the cell stacks 60a, 60b, 60c and 60d, and are directly heated by the combustion flame. Thus, the high temperature generated in the power generation / combustion chamber 12 is effectively used for reforming the reformed gas.

  The combustion gas generated in the power generation / combustion chamber 12 flows into the discharge passage 30 from the discharge opening 42 formed in the heat exchanger 24, and flows through the discharge passage 30 extending in a zigzag shape. 50 is discharged through a discharge passage defined between the outer cylinder member 52 and the inner cylinder member 54. When the combustion gas flows through the discharge path in the double cylinder 50, air flows through the inflow path in the double cylinder 50, and heat exchange is performed between the combustion gas and air.

  Further, when the combustion gas is caused to flow in the exhaust passage 30 of the heat exchanger 24 in a zigzag manner, the air is caused to flow in the inflow passage 32 of the heat exchanger 24 in a zigzag manner. Thus, heat is effectively exchanged between the combustion gas and air to preheat the air.

  When a part or all of the cell stacks 60a, 60b, 60c and 60d deteriorate due to power generation over a long period of time, the front wall (not shown) or the rear wall (not shown) of the housing 2 is shown. The power generation units 56 a, 56 b, 56 c and 56 d are partially or entirely removed from the housing 2.

  Then, replace some or all of the power generation units 56a, 56b, 56c and 56d with new ones, or only the cell stacks 60a, 60b, 60c and 60d in some or all of the power generation units 56a, 56b, 56c and 56d. May be replaced with a new one and mounted again at a required position in the housing 2. Even when it is necessary to replace the reforming catalyst accommodated in the reformers 78a, 78b, 78c and 78d in some or all of the power generation units 56a, 56b, 56c and 56d, the power generation units 56a, 56b , 56c and 56d are removed from the housing 2, and the reformers 78a, 78b, 78c and 78d themselves in the power generation units 56a, 56b, 56c and 56d are replaced with new ones or reformers. Only the reforming catalyst in 78a, 78b, 78c and 78d may be replaced with a new one.

  In order to be able to perform the replacement of the reforming catalyst in the reformers 78a, 78b, 78c and 78d sufficiently easily, a part of the reformers 78a, 78b, 78c and 78d can be opened and closed if desired. It can be put on the door.

  On the other hand, air is supplied to the inflow path 32 of the heat exchanger 24 through the inflow path defined in the inner cylinder member 54 of the double cylinder 50, and is preheated (heated) through the heat exchanger 24. Is temporarily stored in the air chamber 16 and supplied between the cell stacks of the combustion / power generation chamber 12 through the air introduction pipe 22. At this time, the air introduction pipe 22 passes through the combustion region F in which combustion is performed in the vicinity of the fuel gas passage 74 of the fuel cell 62 of the cell stack 60. Accordingly, the preheated air in the air chamber 16 is further heated in the combustion region F above the cell stack 60, and the air heated to a high temperature is supplied to the cell.

  During normal operation, air preheated by the heat exchanger 24 is introduced into the air chamber 16, and air is introduced from the air chamber 16 into the combustion / power generation chamber 12 using the air introduction pipe 22. When the temperature rises more than expected, the low-temperature air that has passed through the low-temperature gas supply pipe 18 that does not pass through the heat exchanger 24 is introduced into the air chamber 16 and preheated through the heat exchanger 24. And the air temperature of the air chamber 16 is reduced to some extent. By supplying this air between the power generation chambers 12, that is, between the cell stacks, air having a lower temperature than that during normal operation is introduced between the cell stacks. Therefore, a good fuel cell assembly that can appropriately control the temperature in the power generation chamber is provided.

  Moreover, since the air temperature in the air chamber 16 is mixed with the outside air supplied from the low temperature gas supply pipe 18 and the air preheated through the heat exchanger 24, the air temperature is not as low as room temperature. Even if the fuel cell 60 is supplied to the hot fuel cell 60, it is possible to avoid problems such as cracks and thermal shock destruction of the fuel cell 60, so that the deterioration of the function of the entire fuel cell power generation system can be suppressed and the life can be extended. .

  Furthermore, by supplying the supply of the low temperature gas from the low temperature gas supply pipe 18 toward the center of the opening of the air supply pipe 22, the air heated from the heat exchangers on both sides is further directed to the center of the opening. The air supplied through the air supply pipe 22 to the center of the cell assembly that is most easily heated can be at the lowest temperature, and the temperature can be increased as the distance from the center increases. can do.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to such embodiments, and various modifications and corrections can be made without departing from the scope of the present invention. It goes without saying that this is possible.

  For example, in the above embodiment, a case has been described in which low temperature gas supply means is provided in the air chamber and air is supplied to the outer surface of the fuel cell by the air supply tube. Of course, air may be supplied to the air. In this case, it goes without saying that an air electrode is formed inside the fuel cell and a fuel electrode is formed outside.

  Further, in the above embodiment, an example in which the low temperature gas supply means is provided in the air chamber has been described. However, it is of course possible to provide the low temperature gas supply means in the fuel gas chamber and cool the fuel cell with the fuel gas. It is. Furthermore, the case where a low temperature gas supply means is not provided may be sufficient.

Sectional drawing which shows suitable embodiment of the fuel cell assembly of this invention. Plan view of FIG. FIG. 2 is a perspective view showing a power generation unit assembly used in the fuel cell assembly of FIG. 1. The power generation unit of FIG. 3 is shown, (a) is a perspective view, (b) is a side view of FIG. Sectional drawing which shows the cell stack of FIG.

Explanation of symbols

2: Housing 12: Power generation / combustion chambers 56a, 56b, 56c and 56d: Power generation units 58a, 68b, 58c and 58d: Fuel gas manifolds 60a, 60b, 60c and 60d: Cell stack 62: Fuel cell 78a, 78b, 78c And 78d: reformer 78a0: reformed gas introduction unit 78a1: reformed gas preheating unit 78a2: reformed gas generating unit 78a3: reformed gas preheating units 80a, 80b, 80c and 80d: fuel gas supply pipe F: combustion area

Claims (4)

In the housing,
It includes a cell stack comprising a plurality of fuel cells of the solid electrolyte are arranged in rows, and arranged to reformer above the cell stack, between the reformer and the cell stack A power generation unit that burns fuel gas that has not been used for power generation of the fuel cell,
The reformer have a reformed gas generator comprising a reforming catalyst to produce a fuel gas supplied to the fuel cell by reforming target gas,
The reformed gas generator extends from above the cell stack to the outside of the end of the cell stack;
A reformed gas introduction part is provided in the extension region of the reformed gas generation part ,
The to-be-reformed gas is introduced into the to-be-reformed gas introduction unit from one end of the reformer, and the reformed gas generated in the to-be-reformed gas generating unit is fed from the other end of the reformer. A fuel cell assembly, wherein the fuel cell assembly is derived . The cell stack is in communication with the fuel gas chamber which is disposed below the cell stack, the reformed gas generated in the reformer, the fuel gas through the reformed gas supply passage The fuel cell assembly according to claim 1 , wherein the fuel cell assembly is supplied to the chamber. Wherein the reformer, the reformed gas preheating section in the direction of flow of the reformed gas, the reformed gas generator, reforming gas preheating section is or Claim 1, characterized in that provided in this order 3. The fuel cell assembly according to 2 . A plurality of power generation units are provided in the housing, and the power generation unit is connected to the reformer and supplies the reformed gas to the reformer. And the reformed gas supply path of one of the adjacent power generation units is disposed to be opposite to the position of the reformed gas supply path of the other power generation unit. The fuel cell assembly according to any one of claims 1 to 3 , wherein

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