JP2006080006A - Internal cooling regenerating type honeycomb-shaped solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell of which the efficiency is superior because it is small-sized while it has a large output, and which is also superior in starting characteristics and load variation characteristics. <P>SOLUTION: This is the fuel cell composed of a honeycomb structural body having a square cell cross-section, and this is the internal cooling regenerating type honeycomb-shaped solid oxide fuel cell, and because a cell adjacent to respective wall faces of a honeycomb cell constituting a fuel electrode cell 3 of the fuel cell is made to be an air electrode cell 5, and the cell adjacent to one wall face of respective air electrode cells which are adjacent to the corner part of a honeycomb cell wall face of the fuel electrode cell and which are positioned on both sides of the corner part is made to be a cooling air cell 6, the fuel electrode cell, the air electrode cell, and the cooling air cell are respectively arranged in skip by every one cell in a lattice form arrangement in a row in the longitudinal direction and the lateral direction, and the cell positioned at the corner part of the honeycomb structural body 1 becomes the fuel electrode cell 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a honeycomb type solid electrolyte fuel cell using any one of a solid electrolyte material, a fuel electrode material and an air electrode material for a honeycomb structure.

Fuel cells range from first-generation fuel cells using a liquid substrate such as an aqueous phosphoric acid solution and molten carbonate to solid polymer fuel cells (hereinafter referred to as PEFC) and solid electrolyte fuel cells (hereinafter referred to as SOFC). To the second generation. Among these second-generation fuel cells, PEFC uses a fluorine-based or hydrocarbon-based polymer electrolyte membrane as an electrolyte. However, the fuel is limited to pure hydrogen (H ₂ ), and it has a very narrow range. Requires temperature control (65-85 ° C.), requires delicate control of moisture (H ₂ O) content in the electrolyte membrane, uses a large amount of expensive platinum catalyst, and durability is 2000 to 3000 There are many drawbacks, such as staying for about hours and not being able to be used in cold regions where freezing is not possible.

  Furthermore, since the fuel is limited to pure hydrogen, it is necessary to completely rebuild the existing social infrastructure (gas, LPG, oil, etc.) into a hydrogen system, which requires enormous social infrastructure investment. These costs are added to the hydrogen production cost, resulting in an increase in unit price per unit calorific value.

  In addition, since the operating temperature is low and therefore the exhaust temperature is also low, for example, it is difficult to effectively recover waste heat in a combined heat and power system (cogeneration system), and if the heat demand exceeds the power demand, supplementary combustion with expensive hydrogen fuel is required. There is a drawback that it is necessary and does not necessarily provide an optimum energy saving system configuration from the viewpoint of heat balance.

  In addition, since PEFC is limited to expensive pure hydrogen fuel, it cannot be said that it is necessarily superior to existing heat engines and hybrid vehicles from the viewpoint of efficiency including hydrogen production cost.

  On the other hand, SOFC can use a wide variety of hydrocarbon fuels other than pure hydrogen, and has the highest theoretical power generation efficiency among all fuel cells. However, since conventional SOFCs use yttria-stabilized zirconia (YSZ) as the electrolyte, they must be operated at a high temperature of about 1000 ° C., and heat resistant ceramics are applied not only to the fuel cell body but also to many parts of the structure. Was used. For this reason, in order to prevent the damage by the thermal stress which generate | occur | produces by the nonuniformity of temperature distribution, it was necessary to start up from several hours to dozens of hours. In addition, there is a drawback that it cannot follow a sudden load fluctuation.

  In recent years, solid electrolyte materials having oxygen ion conductivity equivalent to YSZ at 1000 ° C. at 650 to 800 ° C., such as scandium-stabilized zirconia (ScSZ) and lanthanum galade solid electrolyte (LSGM), have been developed. The metal material can be used for this part, and the degree of freedom in structural design is greatly improved. However, since the structure of the SOFC main body adopts a cylindrical tube group or a flat plate configuration, the thermal stress generated in each part of the structure cannot be sufficiently reduced, and the start-up time cannot be shortened sufficiently. There were drawbacks.

  Furthermore, in order to maintain power generation performance and prevent damage due to thermal stress applied to materials and structures, conventional SOFCs must maintain the temperature inside the system uniformly at a high temperature of about 1000 ° C. In addition, the exhaust gas was sucked and mixed with a venturi or the like and forcedly circulated. For this reason, both the fuel concentration and the oxygen concentration are diluted and supplied in a low concentration state, and there is a drawback that the output density per unit area of the fuel cell cannot be increased.

  In order to describe these in more detail, the system configuration and function of a conventional typical SOFC battery using a cylindrical cell unit will be described with reference to FIG.

  The fuel is supplied from the fuel inlet 61, heated while passing through the cylindrical internal reformer 62, reversed at the end, and flows in the direction of the arrow 63 along the fuel electrode. After passing through the return line 64, the fuel exhaust gas containing unreacted fuel is sucked from the fuel inlet venturi 65 and returned to the fuel supply line. The surplus fuel exhaust gas is supplied to the combustor 74 through the fuel exhaust pipe 66.

  On the other hand, air, which is an oxidant, is supplied from the air inlet 77 and preheated while flowing from the air header 68 in the direction of the arrow 69, reverses at the end of the cell unit, flows in the direction of the air electrode 70, and fuel. Supply oxygen to the battery. The air after supplying oxygen to the fuel cell flows through the air exhaust pipe in the direction of arrow 71, is sucked from the air inlet venturi 72, and returned to the air supply line. Excess air exhaust flows through the exhaust pipe in the direction of the arrow 73, mixes with the fuel exhaust gas in the combustor 74, burns, and is exhausted from the exhaust port 76 through the exhaust pipe 75.

  Because of this structure, the conventional SOFC makes the temperature of the entire cell unit uniform from the cold state to the high temperature state where power can be generated and avoids damage due to thermal stress while forcibly circulating fuel gas and air. It is necessary to gradually raise the temperature. For this reason, it takes a lot of time to warm up until the apparatus is started and reaches full power, which is not convenient.

  Further, in the conventional SOFC, both the fuel side and the air side suck the exhaust gas using a venturi, mix it with the supply gas, and forcibly circulate it in a diluted state. Since it is configured such that it is mixed with air and combusted and released into the atmosphere, the exhaust gas contains a large amount of unreacted fuel and unreacted oxygen, which has the drawback that the power generation efficiency cannot be sufficiently increased.

  On the other hand, there are Patent Document 1 and Patent Document 2 as examples of a honeycomb-structured fuel cell using a solid electrolyte.

  The fuel cell patents disclosed in these patent documents are honeycomb structures using yttria-stabilized zirconia (YSZ) and scandium-stabilized zirconia (ScSZ) as solid electrolytes. This is a honeycomb type fuel cell forming a so-called checkered pattern in which polar cells are alternately arranged, and in any case, no means for effectively removing the heat generated inside the honeycomb cell is provided. Therefore, while heat is accumulated inside the honeycomb and the internal temperature is increased, the outer peripheral portion of the honeycomb is cooled by heat dissipation and cooling, and a large temperature difference occurs between the central portion of the honeycomb and the outer peripheral portion. There was a problem that the honeycomb was damaged by the thermal stress due to the temperature difference.

  Therefore, as in the conventional example shown in FIG. 85, the fuel cell uses a venturi to suck the exhaust gas so that a large thermal stress does not occur inside the honeycomb cells constituting the fuel cell. It is necessary to mix with the supply gas and forcibly circulate the diluted gas, and it is necessary to warm up slowly enough time for warming up to start normal operation and full power. There was a drawback lacking.

In addition, the fuel gas and air are forced to circulate by sucking and mixing the exhaust gas using a venturi, so that the concentration of the fuel in the circulating fuel gas and the oxygen in the circulating air is diluted and the concentration decreases. The concentration of the unreacted fuel gas contained and the unreacted oxygen concentration also increased, and as a result, the power generation efficiency could not be sufficiently increased. In addition, there is a drawback that the output density per unit area cannot be increased.
Japanese Patent Laid-Open No. 10-189023 JP 11-297343 A

  The present invention has been made to overcome the above-mentioned drawbacks. By uniformly cooling the inside of the honeycomb, the temperature difference generated inside and outside of the fuel cell is reduced to prevent the generation of thermal stress. Supply the fuel cell with high concentration without dilution with air, and also generate power until the remaining unreacted fuel in the exhaust fuel gas at the outlet of the fuel cell and the remaining unreacted oxygen in the exhaust air are sufficiently low in concentration. An object of the present invention is to provide a SOFC type fuel cell that is small in size, has a high output and is efficient, and has excellent start-up characteristics and load fluctuation characteristics.

  The present inventor, as a honeycomb type solid electrolyte fuel cell for achieving the above object, constituted a fuel cell from a honeycomb structure having a quadrangular cell cross section, and a honeycomb cell constituting a fuel electrode cell of the fuel cell. A cell adjacent to each wall surface is an air electrode cell, a cell adjacent to each corner of the honeycomb cell wall surface of the fuel electrode cell and one wall surface of each of the air electrode cells located on both sides of the corner portion Proposal of an internal cooling type solid electrolyte fuel cell in which the fuel cell, the air electrode cell, and the cooling air cell are arranged in a grid pattern in the vertical direction and the horizontal direction in a grid pattern by using the cooling air cell. did. (See Japanese Patent Application No. 2003-70854)

  Further, as a result of further study of the honeycomb type solid electrolyte fuel cell from the viewpoint of performance and economy, as a preferred embodiment thereof, a cell located at a corner portion of the honeycomb structure is the fuel electrode cell, more preferably a cross section. An outer peripheral surface of the honeycomb structure is provided by providing a cover formed of a material different from the material of the honeycomb structure on each surface of the outer periphery of the rectangular honeycomb structure and providing an air electrode passage or the like in the cover. Has also found that a honeycomb solid electrolyte fuel cell having a high output density and contributing to power generation can be obtained, and the present invention has been achieved.

  That is, the present invention is a fuel cell comprising a honeycomb structure having a square cell cross section, wherein the cells adjacent to the respective wall surfaces of the honeycomb cells constituting the fuel cell of the fuel cell are air electrode cells, and the fuel The cell adjacent to the corner of the wall surface of the electrode cell and adjacent to one wall surface of the air electrode cell located on both sides of the corner is a cooling air cell, whereby the fuel electrode cell, the air electrode cell, and the cooling Honeycomb-type solid, wherein air cells are arranged in a grid pattern in which one cell jumps vertically and horizontally, and the cells located at the corners of the honeycomb structure are the fuel electrode cells. An electrolyte fuel cell is provided.

  In the present invention, a cover formed of a material different from the material of the honeycomb structure is provided on the outer peripheral surface of the honeycomb structure having a rectangular cross section, and an air electrode passage and a cooling air passage are formed in the cover. There is provided the above-described honeycomb type solid electrolyte fuel cell in which an air electrode passage is adjacent to a wall surface of a fuel electrode cell located on an outer peripheral portion of a honeycomb structure.

  In the present invention, when the honeycomb structure is formed of any one of a solid electrolyte material, a fuel electrode material, and an air electrode material, and the honeycomb structure is formed of a solid electrolyte material, the inner surface of the fuel electrode cell honeycomb The internal cooling regenerative honeycomb solid electrolyte fuel cell is provided by forming a fuel electrode on the inner surface of each of the air electrode cells.

  Further, the present invention provides a fuel cell group formed by stacking two or more of the above honeycomb type fuel cells, and connecting the fuel electrode and the air electrode of the honeycomb type fuel cells that are connected to each other with an interconnector. There is provided a honeycomb type solid electrolyte fuel cell characterized in that electricity is taken out by current collectors provided at both ends of the cell group.

  Furthermore, the present invention provides an anode cell closing surface at the end of the honeycomb type fuel cell located at one end of the fuel cell group, and the air electrode cell flow path and the cooling air cell flow path penetrate therethrough. Connecting the first current collector, connecting an exhaust collecting chamber having a cooling air flow path through the current collector, connecting an air inlet chamber or an air inlet pipe to the exhaust collecting chamber, and A second current collector through which the fuel electrode cell flow path, the air electrode cell flow path and the cooling air cell flow path penetrated is connected to the end of the honeycomb structure located at the other end of the An air reversing chamber and a fuel exhaust collecting chamber through which a fuel supply pipe penetrates are sequentially connected, and a fuel supply chamber or a fuel supply pipe is connected to the fuel exhaust collecting chamber. Near the air inlet / outlet side end face of the fuel cell. The fuel supply pipe extends to provide a honeycomb type solid electrolyte fuel cell, which comprises inserting provided fuel electrode cell inner surface and the gap.

  The present invention includes an air inlet chamber or an air inlet pipe, an exhaust collecting chamber, one end side current collector, a honeycomb fuel cell, another end side current collector, an air reversing chamber, a reaction product collecting chamber, a fuel supply pipe And the above-mentioned honeycomb type solid electrolyte fuel cell in which a plurality of functional parts of a fuel supply chamber or a fuel supply pipe are integrally formed or joined together to have a plurality of functions.

  The present invention is also characterized in that, in the above-described honeycomb type solid electrolyte fuel cell, the fuel supply pipe is filled with a fuel reforming catalyst, and the fuel reforming is performed in the fuel supply pipe.

In the present invention, the honeycomb structure of the above-described honeycomb type solid electrolyte fuel cell is made of yttria stabilized zirconia (YSZ), scandium stabilized zirconia (ScSZ), lanthanum / strontium solid electrolyte, C12A7 (12CaO · 7Al ₂ O ₃ ), or the like. It is characterized by comprising a solid electrolyte having ionic conduction such as O ⁻ , O ²⁻ , H ⁺ , H ^{− and the} like.

  According to the present invention, as in the prior art, both fuel and reaction air are not used by sucking and diluting the exhausted air and exhausted fuel gas to circulate, so that high concentration fuel and high oxygen concentration air are used. This improves power generation output per unit surface area, contributing to downsizing and weight reduction.

  In addition, the unreacted fuel concentration in the exhaust fuel gas exhausted from the fuel cell and the oxygen concentration in the exhausted air can be greatly reduced, and the cooling air that has taken away the heat generated inside the honeycomb structure and increased in temperature is The direction is reversed and sent to the air electrode cell and used as reaction air for functioning as a fuel cell, so that heat is recovered and the power generation efficiency is greatly improved.

  In addition, since the inside of the honeycomb structure can be uniformly cooled, there is no temperature difference between the inside and the outer periphery of the honeycomb structure, and thermal stress can be greatly reduced, enabling rapid start-up and rapid load fluctuations. It can also follow quickly. In addition, it is not necessary to make the fuel gas and air high in order to drive the venturi as in the prior art, and the power required to make the fuel cell function can be minimized. In addition, the residual unreacted fuel in the exhaust fuel gas at the outlet of the fuel cell and the residual unreacted oxygen in the exhaust air can be used for power generation until the concentrations are sufficiently low.

  Further, according to the present invention, since the cell located at the corner portion of the honeycomb structure having a rectangular cross section constituting the fuel cell is a fuel electrode cell, the outer peripheral surface of the honeycomb structure can also contribute to power generation. Even with the honeycomb structure, the power generation output can be greatly improved.

  Further, by providing a cover on the outer peripheral surface of the honeycomb structure and forming an air electrode passage and a cooling air passage in the cover, cooling of the cells arranged on the outer periphery of the honeycomb structure can be obtained. Since the enlargement can be suppressed and the cover can be formed of a material cheaper than the material of the honeycomb structure, the cost of the fuel cell can be reduced.

  The structure and function of the honeycomb type solid electrolyte fuel cell according to the present invention will be described in more detail with reference to FIGS. The drawings illustrate preferred embodiments of the present invention and the present invention is not limited thereto.

  In the present invention, the honeycomb structure can be formed from any of a solid electrolytic material, a fuel electrode material, and an air electrode material, but a solid electrolytic material is usually preferable. Even when the honeycomb structure is formed of the fuel electrode material or the air electrode material, all of them are the same except that either the fuel electrode or the air electrode has a double membrane structure of the electrolyte membrane and the electrode membrane. All explanations will be made with an example in which the honeycomb structure is formed of a solid electrolyte.

  A solid oxide fuel cell according to the present invention forms a fuel electrode 2 formed by coating or joining and firing on the inner surface of a honeycomb structure 1 of a solid electrolyte having a square cell cross section with both ends opened. A fuel electrode cell 3 (indicated by symbol (a) in the figure) is formed on the inner surface of the cell adjacent to the wall surface constituting the fuel electrode cell 3 by coating or joining and firing the air electrode 4 integrally. The air electrode cell 5 (indicated by the symbol (b)) is formed, and is adjacent to the corner portion of the wall surface constituting the fuel electrode cell 3, and each one of the air electrode cells 5 located on both sides of the corner portion. A cell adjacent to the wall surface is a cooling air cell 6 (indicated by symbol (c)). By adopting such a configuration, the honeycomb structure 1 has a fuel cell 3, an air electrode cell 5, and a cooling air cell 6, each of which is arranged in a regular manner in the vertical direction and the horizontal direction in a jump of one cell. An eye array is obtained.

  In FIG. 1, the fuel electrode cell 3, the air electrode cell 5, and the cooling air cell 6 of the honeycomb structure 1 are all passages and are squares having the same cell cross-sectional shape. All cell sections need not be the same as long as they can be achieved. Further, the shape may be generally rectangular. In one honeycomb body of a preferred embodiment, the cell cross section can be changed depending on the cell types a, b, and c. For example, as shown in FIG. 4, the cell cross section can be changed depending on the cell types a, b, and c. That is, the cell cross section of the anode cell 3 is a square, the cell cross section of the air electrode cell 5 is a rectangle with the wall surface of the anode cell 3 as the long side, and the cell cross section of the cooling air cell 6 is the rectangular cross section. The air electrode cell 5 may have a rectangular cross section with a square having the short side as one side or a circle with the short side of the air electrode cell 5 having a diameter. Here, the cell cross section is a cross section in a direction orthogonal to the passage of each cell of the honeycomb structure 1.

  Thus, by changing the cell cross section of the honeycomb body 1 depending on the cell type and relatively increasing the cell cross section or the volume of the fuel electrode cell 3, the output per volume in the honeycomb body of the same unit volume of the fuel cell can be increased. . As a result of enlarging the cell cross section of the anode cell 3, the cell sections of the air electrode cell 5 and the cooling air cell 6 are smaller than those of the anode cell 3, and in particular, the cell cross section of the cooling air cell 6 is reduced. There is no problem if the cell cross-sectional ratio is optimized.

  Furthermore, as illustrated in FIG. 5, a modified quadrangle in which a part or all of each side of a cell having a quadrangular cell cross section is curved or wavy may be used. When each side of the cell is curved or waved in this way, the electrode area increases, so that the output per unit volume of the fuel cell can be further increased.

In the honeycomb structure 1, by arranging the cells having a square cell cross section as described above, the honeycomb structure 1 having a rectangular cross section can be easily obtained.
In this case, the number of cells arranged in the honeycomb structure 1 is not limited. Although FIG. 1 shows an example in which the cells are arranged in 5 rows × 5 columns, the number of cells can be increased or decreased, and the number of rows and columns may be changed. The number of arrangements is preferably 5 to 13 rows (columns), and particularly practically 7 to 11 rows (columns).

  The present invention is characterized in that in the arrangement of the fuel electrode cell 3, the air electrode cell 5 and the cooling air cell 6, the cell located at the corner of the honeycomb structure 1 is the fuel electrode cell 3. Usually, in order to increase the power density per unit area of the honeycomb structure 1, it is preferable to use the cells located at the four corners of the honeycomb structure as fuel electrode cells as shown in FIG.

  Furthermore, a cover 78 made of a material different from the material of the honeycomb structure 1 is provided on each surface of the outer periphery of the honeycomb structure 1 by bonding or fastening. Inside the cover 78, air electrode passages b ′ and cooling air passages c ′ are alternately formed by partition walls, and the air electrode passages b ′ and cooling air passages c ′ are formed on the outer periphery of the honeycomb structure 1. It arrange | positions so that it may each adjoin to one side of the fuel electrode cell 3 and the air electrode cell 5 which are formed in a surface. That is, the air electrode passage b ′ is adjacent to the wall surface of the fuel electrode cell 3, and the cooling air passage c ′ is adjacent to the wall surface of the air electrode cell 5. An air electrode 4 ′ is formed on the outer peripheral surface of the honeycomb structure 1 constituting one side of the air electrode passage b ′ adjacent to the wall surface of the fuel electrode cell 3.

  The air electrode passage b ′ and the cooling air passage c ′ formed inside the cover 78 are adjacent to only a part of the sides of the combustion electrode cell 3 and the air electrode cell 5 arranged in the honeycomb structure 1, respectively. Therefore, the air volume and the cooling performance which are as large as those of the air electrode cell 5 and the cooling air cell 6 of the honeycomb structure 1 are not required. Therefore, the cross-sectional areas of these two flow paths can be about half or less than the cross-sectional areas of the air electrode cell 5 and the cooling air cell 6 in the honeycomb structure 1. For example, when the cell cross section of the honeycomb structure 1 is square, the air electrode passage b ′ and the cooling air passage c ′ have the same long side as one side of the fuel electrode cell 3 or the air electrode cell 5 and the short side thereof. It can be a rectangular cross-section with about half the length. As a result, the cover 78 can be made thin as a whole as shown in FIG. 1, and the fuel cell can be prevented from being enlarged and the material can be saved.

  FIG. 6 shows another embodiment of the cover 78. The cover 78 of FIG. 1 has the air electrode passages b ′ and the cooling air passages c ′ alternately arranged as described above, and the air electrode 4 ′ is provided on the wall surface of the fuel electrode adjacent to the air electrode passage b ′. As shown in FIG. 6, the cover 78 of this example is provided with only the air electrode passage b ′ inside the cover, and the entire outer peripheral surface of the honeycomb structure 1 is used as the air electrode 4 ′. Since the outer peripheral surface of the cover 78 can be used as a cooling surface, the temperature of the outer peripheral surface of the honeycomb structure 1 and the cells adjacent to the outer peripheral surface can be increased without providing a cooling air passage inside the cover. By being able to suppress.

  The material of the cover 78 is different from the material of the honeycomb structure 1 as described above, for example, ceramics such as alumina, zirconia, mullite, cordierite, silicon carbide and silicon nitride, or heat resistant steel such as stainless steel and inconel. Is preferably used. Since these materials are cheaper than the expensive solid electrolyte material of the honeycomb structure and further have good thermal conductivity, the outer peripheral surface of the cover can be effectively used as a cooling surface.

  Due to the cell arrangement of the honeycomb structure 1 and the cooling flow path of the cover 78, the fuel electrode cell 3 positioned inside the honeycomb structure 1 has all the wall surfaces constituting the cell adjacent to the air electrode cell 5. The cooling air cell 6 has all wall surfaces adjacent to the air electrode cell 5, while the fuel electrode cell 3 and the air electrode cell 5 located on the outer peripheral portion of the honeycomb structure 1 are formed by the outer peripheral surface of the honeycomb structure 1. Since the wall surface is adjacent to the air electrode passage b ′ and the like of the cover 78, a cooling flow path for uniformly cooling the inside of the honeycomb structure 1 can be secured.

  In the present invention, the outer peripheral surface of the honeycomb structure 1 can be effectively used for power generation by the combination of the cell arrangement structure of the honeycomb structure 1 and the cooling structure by the cover 78. Compared to the case where the cells to be made are not the anode cells, the number of anode cells can be increased from 4 to 9, despite the honeycomb structure 1 having the same 5 columns × 5 rows, for example, The power generation output can be increased 2.25 times.

  FIG. 2 is a cross-sectional view taken along the line II of FIG. The fuel flows through the anode cell 3 in the direction of the arrow 7 to the arrow 8 in FIG. 2, while the reaction air flows in the direction of the arrow 9 to the arrow 10 in the opposite direction to the flow direction of the fuel, The local electromotive force from the fuel inlet side to the outlet side can be made uniform.

  Further, it is desirable that the air flowing through the cooling air cell 6 flows in the direction of the arrow 11 to the arrow 12 in the opposite direction to the reaction air so that the air electrode cell 5 whose temperature rises due to internal heat generation can be effectively cooled.

  In such a cell structure, the fuel electrode 2 has a rectangular flange type fuel electrode interface extending from one end face side (right side in FIG. 2) of the honeycomb structure 1 along the fuel electrode cell 3 partition wall end. The connector part 16 is provided, and the other end surface side of the honeycomb structure 1 is made shorter than the entire length of the honeycomb structure 1 by the dimension X, and the air electrode 4 extends the other end surface side of the honeycomb structure 1 along the partition wall end. Thus, the honeycomb fuel cell 17 can be configured by providing the square flange type air electrode interconnector portion 15 and making one end of the honeycomb structure 1 shorter than the entire length of the honeycomb structure 1 by the dimension Y.

  The dimensions X and Y are determined in consideration of the material of the honeycomb structure 1 and the electric conductivity of the fuel, but are preferably about 0.5 to 5.0 mm. By providing regions (dimensions X and Y) in which the fuel electrode 2 and the air electrode 4 are not formed in the fuel electrode cell 3 and the air electrode cell 5 in the above ranges, a plurality of honeycomb fuel cells 17 are described later. When stacked in such a manner, electrical insulation between the same polarities of adjacent honeycomb fuel cells 17 (fuel electrode and fuel electrode or air electrode and air electrode) is maintained.

The interconnectors 16 and 15 of the honeycomb fuel cell 17 may be the same as the constituent materials of the fuel electrode 2 and the air electrode 4, respectively. However, since the surface in contact with the fuel electrode cell 3 is a strong reducing atmosphere, while the surface in contact with the air electrode cell 5 is a strong oxidizing atmosphere, a material that is resistant to both oxidation and reduction is preferable. As this material, for example, oxide materials such as LaCrO ₃ , La _0.8 Ca _0.2 CrO ₃ , La _0.7 Sr _0.3 CrO ₃ , noble metals such as Au and Ag, and heat resistant steels such as Inconel and stainless steel are used.

  FIG. 3 shows the structure and function of an application example of a solid oxide fuel cell according to the present invention. Stacking is performed so that the air electrode interconnector 15a of the first-stage honeycomb fuel cell 17a and the fuel electrode interconnector 16b of the second-stage honeycomb fuel cell 17b are connected to each other. A laminated honeycomb fuel cell 18 in which n stages of 17 are connected in series is obtained.

  The connection between the air electrode interconnector 15a and the fuel electrode interconnector portion 16b on the laminated surface is integrated by pressure bonding or bonding to form the interconnector portion 13 (see FIG. 3).

  Note that the method of stacking the air electrode interconnector 15 and the fuel electrode interconnector 16 is the opposite of the configuration shown in FIG. The portion 16n may be exposed, and the air electrode interconnector portion 15n may be exposed on the right end surface.

The fuel supplied to the laminated honeycomb fuel cell 18 is supplied from the direction of the IIIa surface shown in FIG. 3 into the fuel electrode cell (a) from the direction of the arrow 19 and is generated by an electrochemical reaction at the fuel electrode (H ₂ O) and a mixed gas of unreacted hydrogen (H ₂ ), carbon dioxide (CO ₂ ) and nitrogen (N ₂ ), or a mixed gas of water vapor, unreacted hydrogen and carbon dioxide, and flows out from the arrow 20 To do.

  On the other hand, the cooling air for cooling the inside of the laminated honeycomb fuel cell 18 is supplied in the direction of the arrow 21 into the cooling air cell (c) from the same IIIa surface side as the fuel inflow direction. The cell wall is cooled to raise its own temperature. The air after cooling the cell wall flows out from the end surface IIIb in the direction of the arrow 22. The hot air flowing out from the arrow 22 reverses direction, flows into the reaction air cell (b) from the end surface IIIb in the direction of the arrow 23, supplies oxygen to the air electrode 4, and reduces the oxygen concentration while reducing the oxygen concentration ( It flows out in the direction of the arrow 24 from the end surface IIIa of b).

  Note that the number of stacked honeycomb fuel cells 18 formed by stacking the honeycomb fuel cells 17 is the length of the single cell constituting the cell, the required output voltage, the electrolyte material to be selected, the cell size of the honeycomb structure, the exhaust The optimum number of layers is determined in consideration of the ratio of unreacted fuel in the fuel, the heat balance of the entire system, and the economic efficiency of the entire system. Therefore, the number of laminated layers of the laminated honeycomb fuel cell 18 is not specified, but is usually 3 to 10.

As the solid electrolyte material used for the honeycomb structure 1, yttria stabilized zirconia (YSZ), scandium stabilized zirconia (ScSZ), lanthanum galade based solid electrolyte material (LSGM, LSGMC) or C12A7 (12CaO · 7Al ₂ O ₃ ) And so on. Furthermore, as LSGM, La _0.8 Sr _0.2 Ga _0.8 Mg _0.2 O _x and La _0.9 Sr _0.1 Ga _0.8 Mg _0.2 O _x , and as LSGMC, La _{0 .8 Sr 0.2 Ga 0.8 Mg 0.15 Co} 0.05 O x and _{La 0.9 Sr 0.1 Ga 0.8 Mg 0.1} 5Co 0.05 O x are exemplified. Then, YSZ as, for example, as 8 _{mol% Y 2 O 3 · ZrO 2} , ScSZ that the ZrO ₂ doped with _Y 2 _{O 3} 8 mol% Sc ₂ O ₃ · 3ZrO ₂ etc. are preferably used. These are substances having O ⁻ and O ²⁻ ion conductivity, but substances having H ⁺ and H ⁻ ion conductivity which are being studied in recent years are also included in the solid electrolyte material defined in the present invention.

As the electrode film material, known or well-known materials can be used, for example, Ni and Ni cermet for the anode (fuel electrode), LaMnO ₃ , La _0.8 Sr _0.2 MnO _{3 for} the cathode (air electrode), LaCoO ₃ , La _0.5 Sr _0.5 CoO _{3 and the} like can be cited as preferable materials, respectively.

  1 to 3, all the material constituting the honeycomb structure 1 is a solid electrolyte material. However, the honeycomb structure 1 is composed of an air electrode material, and the inner surface of the fuel electrode cell is coated with an electrolyte material. Further, the fuel electrode material may be coated or bonded to form two layers. Alternatively, the honeycomb structure 1 may be formed of a fuel electrode material, coated or joined with an electrolyte material on the inner surface of the air electrode cell, and further coated or joined with the air electrode material to form two layers.

  An embodiment of the honeycomb type fuel cell according to the present invention will be described in more detail with reference to FIG. The laminated honeycomb fuel cell 18 is a honeycomb structure composed of 5 rows × 5 columns of cells in FIGS. 1 to 3, whereas in FIG. 7, it has a configuration of 7 rows × 7 columns, which is closer to the actual machine. However, all other structures and functions other than this point are substantially the same as those described in FIGS. Further, a cover is provided on each surface of the outer periphery of the honeycomb structure, but the illustration is omitted.

  Note that FIG. 7 is a diagram separated into two upper and lower stages, but this is divided into two stages for convenience of arrangement of the figure, and in fact, all the parts are connected in series on one center line. Is.

  In the laminated honeycomb fuel cell 18, a honeycomb-shaped air inlet / outlet current collecting / insulating unit 26 closed only at the fuel flow path is connected to the air inlet / outlet side end face 25 along the arrow 28 and integrated.

  The air input / output side current collecting / insulating unit 26 including the first current collector 29 and the insulator 30 is further connected to the air input / output unit 31 on the upstream side thereof. This air inlet / outlet unit 31 has a space 33 and an exhaust port 34 through which a cooling air conduit 32 communicating with the cooling air cell 6 (see FIG. 1) passes, and exhaust air from the fuel cell is indicated by an arrow from the exhaust port 34. Exhaust in the direction of 54.

  The cooling air is supplied to the header portion 35 from the arrow 36, is distributed substantially evenly to the cooling air conduit 32 communicating with the header portion 35, passes through the current collecting and insulating unit 26, and is supplied to the laminated honeycomb fuel cell 18.

  On the other hand, the fuel provided on the fuel supply side end surface 37 of the laminated honeycomb fuel cell 18 includes a second current collector 38 and an insulator 39 that have cells penetrating therethrough and having the same cell cross-sectional shape as the laminated honeycomb fuel cell 18. A supply-side current collecting and insulating unit 40 is connected. An air reversing unit 44 having an air reversing chamber 43 through which a fuel electrode conduit 42 communicating with the fuel electrode cell passes is connected to the fuel supply side end face 41 of the current collecting and insulating unit 40, and the air passing through the cooling air cell is After gathering in the air reversing chamber 43, it is reversed and flows into the reaction air electrode cell.

  Further, a fuel gas exhaust unit 49 is connected to the end face 45 of the air reversing unit 44. The fuel gas exhaust unit 49 includes a fuel supply pipe 46, a fuel exhaust collecting chamber 47, and a fuel exhaust gas outlet 48. The fuel supply pipe 46 has a fuel electrode conduit 42 that passes through the air reversing unit 44, a current collector. An air inlet / outlet side end surface of the laminated honeycomb fuel cell 18 having a proper gap between the cell communicating with the fuel electrode of the insulating unit 40 and the fuel electrode cell of the laminated honeycomb fuel cell 18 and having a gap with the fuel electrode. It extends to the vicinity of 25.

The fuel exhaust gas is reversed at the air inlet / outlet side end face 25 of the laminated honeycomb fuel cell 18 and passes through the gap between the fuel reforming pipe fuel supply pipe 46 and the fuel electrode 2 (see FIG. 1), and during this time, it reacts with the reaction air. To generate electricity. After the power generation, the fuel exhaust gas collects in the fuel exhaust collecting chamber 47 and is then exhausted from the fuel exhaust gas outlet 48 in the direction of the arrow 50. Further, a fuel supply header 52 is connected to the fuel inlet side end face 51 of the fuel exhaust collecting chamber 47, and the fuel supplied into the fuel supply header 52 from the arrow 53 is distributed substantially evenly by the fuel supply header 52. Then, the fuel reforming pipe is supplied to the fuel supply pipe 46. Further, the fuel supply pipe 46 is filled with a fuel reforming catalyst, for example, a catalyst in which nickel (Ni) is dispersedly supported on a ceramic substrate, and the fuel gas passing through the fuel supply pipe is converted into a mixed gas of H ₂ and CO by the catalyst. By reforming, the reformed gas can be supplied to the fuel electrode without depositing carbon (C).

  The exhaust air exhausted from the arrow 54 and the fuel exhaust gas exhausted from the arrow 50 are mixed and burned by a combustor (not shown) through a pipe or a structural space (not shown), and released to the atmosphere.

The exhaust gas mixed and burned in the combustor may be preheated with cooling air by a heat exchanger (not shown) to recover the heat. Furthermore, the exhaust gas mixed and burned in the combustor may be pressurized with cooling air by a gas turbine (not shown) consisting of an air compressor and a turbine to keep the entire system in a pressurized state, thereby improving power generation efficiency and downsizing. Good.
Further, in the solid electrolyte fuel cell illustrated in FIG. 7, solid fuel cells such as a honeycomb type fuel cell, a first current collector, a second current collector, an air reversing chamber, an exhaust fuel reaction product collecting chamber, and a fuel supply pipe. Although the functional parts constituting the electrolyte fuel cell are manufactured as separate members, those that can be molded integrally or joined together can not be manufactured as separate members. You may integrate suitably.

  The present invention uniformly cools the inside of the honeycomb to reduce the temperature difference generated inside and outside of the fuel cell to prevent the generation of thermal stress, and the fuel cell remains at a high concentration without diluting both fuel and air. In addition, the remaining unreacted fuel in the exhaust gas at the outlet of the fuel cell and the remaining unreacted oxygen in the exhaust air are used for power generation until the concentration is sufficiently low. In addition, the present invention can be applied to SOFC type fuel cells having excellent start-up characteristics and load fluctuation characteristics.

1 is a simplified cross-sectional view of a fuel cell according to an embodiment of the present invention. Sectional drawing in II of FIG. 1 and FIG. 6 of the fuel cell single cell which concerns on the Example of this invention. Sectional drawing similar to the II cross section of FIG. 1 of the laminated fuel battery cell by this invention. Sectional drawing of the honeycomb structure of the fuel cell which concerns on the other Example of this invention. The fragmentary sectional view of the honeycomb structure of the fuel cell concerning other another example of the present invention. FIG. 4 is a simplified cross-sectional view of a fuel cell according to another embodiment of the present invention. The bird's-eye view which shows an example which comprised the fuel cell unit using the laminated fuel battery cell by this invention. The system diagram of the solid oxide fuel cell by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Honeycomb structure 2 Fuel electrode 3 Fuel electrode cell 4 Air electrode 5 Air electrode cell 6 Cooling air cell 13 Interconnector part 15 Air electrode interconnector part 16 Fuel electrode interconnector part 17 Honeycomb fuel cell 17a First stage honeycomb fuel cell 17b Second-stage honeycomb fuel cell 17n n-th stage honeycomb fuel cell 18 stacked honeycomb fuel cell 25 air inlet / outlet side end face 26 air inlet / outlet current collecting / insulating unit 29 first current collector 30 insulator 31 air inlet / outlet unit 32 cooling air conduit 33 Space 34 Exhaust port 35 Header portion 37 Fuel supply side end face 38 Second current collector 39 Insulator 40 Current collecting insulation unit 41 Fuel supply side end face 42 Fuel electrode conduit 43 Air reversing chamber 44 Air reversing unit 45 End face 46 Fuel reforming pipe 47 Exhaust fuel collecting chamber 48 Exhaust fuel exhaust port 49 Exhaust unit 51 End face of fuel inlet 52 Fuel supply header 61 Fuel inlet 62 Internal reformer 64 Return line 65 Fuel inlet venturi 66 Fuel exhaust pipe 67 Air inlet 68 Air header 70 Air electrode 71 Air exhaust pipe 72 Air inlet venturi 74 Combustor 75 Exhaust Pipe 76 Exhaust port 77 Air inlet 78 Cover

Claims (14)

  A fuel cell comprising a honeycomb structure having a quadrangular cell cross section, the cell adjacent to each wall surface of the honeycomb cell constituting the anode cell of the fuel cell being an air electrode cell, and the honeycomb cell of the anode cell By making a cell adjacent to one wall surface of each of the air electrode cells adjacent to the corner of the wall surface and located on both sides of the corner into a cooling air cell, the fuel electrode cell, the air electrode cell, and the cooling air cell are Internal cooling regeneration, wherein each cell is arranged in a grid pattern in the vertical direction and the horizontal direction in one cell jump, and the cells located at the corners of the honeycomb structure are the fuel electrode cells. Honeycomb type solid electrolyte fuel cell.   The honeycomb structure has a rectangular cross section, and a cover formed of a material different from the material of the honeycomb structure is provided on each surface of the outer periphery of the honeycomb structure, and the cover includes an air electrode passage and a cooling air passage. 2. The honeycomb type solid electrolyte fuel cell according to claim 1, wherein the air electrode passage is disposed adjacent to an outer peripheral surface of the honeycomb structure forming a wall surface of the fuel electrode cell.   The honeycomb structure has a rectangular cross section, and a cover formed of a material different from the material of the honeycomb structure is provided on each outer surface of the honeycomb structure, and the cover has an air electrode passage inside, The honeycomb type solid electrolyte fuel cell according to claim 1, wherein an air electrode passage is in contact with an outer peripheral surface of the honeycomb structure.   The honeycomb solid electrolyte fuel cell according to claim 2 or 3, wherein an air electrode is provided on an outer peripheral surface of the honeycomb structure adjacent to the air electrode passage.   The honeycomb type solid electrolyte according to claim 2, 3 or 4, wherein the cover is made of ceramics such as alumina, zirconia, mullite, cordierite, silicon carbide, silicon nitride, or heat resistant steel such as stainless steel or inconel. Fuel cell.   The honeycomb structure is formed of any one of a solid electrolyte material, a fuel electrode material, and an air electrode material. When the honeycomb structure is formed of a solid electrolyte material, the fuel electrode is disposed on the inner surface of the fuel electrode cell honeycomb. The internally cooled regenerative honeycomb type solid electrolyte fuel cell according to any one of claims 1 to 5, wherein an air electrode is formed on an inner surface of each air electrode cell.   The honeycomb solid electrolyte fuel cell according to any one of claims 1 to 6, wherein the cell cross sections are squares having the same shape.   The cell cross section of the anode cell is a square, the cell cross section of each air electrode cell is a rectangle having the long side of each wall surface of the anode cell, and the cell cross section of the cooling air cell is the short side of the air electrode cell. A honeycomb type solid electrolyte fuel cell according to any one of claims 1 to 7, which is a square having one side as a square or a circle having a short side as a diameter.   The honeycomb type solid electrolyte fuel cell according to any one of claims 1 to 8, wherein a part or all of the wall surfaces of the fuel electrode cell, the air electrode cell, and the cooling air cell each having a square cell cross section are curved or wavy.   Two or more honeycomb type solid electrolyte fuel cells according to any one of claims 1 to 9 are laminated to form a fuel cell group, and the fuel electrode and air electrode of the fuel cells connected to each other are connected by an interconnector. The internal cooling regenerative honeycomb solid electrolyte fuel cell is characterized in that electricity is taken out from current collectors provided at both ends of the cell group. A first current collector provided with an anode cell closing surface at the end of a honeycomb type fuel cell located at one end of a fuel cell group, and through which a flow path of an air electrode cell and a flow path of a cooling air cell pass An air inlet / outlet unit through which a cooling air conduit penetrates is connected to the first current collector, and an exhaust collecting chamber through which a cooling air flow path passes is connected to the current collector, to the exhaust collecting chamber. Connect the air inlet chamber or air inlet pipe,
A second current collector in which the flow path of the fuel electrode cell, the flow path of the air electrode cell, and the flow path of the cooling air cell pass through the end of the honeycomb type fuel cell structure located at the other end of the cell group A fuel supply header for supplying fuel to the fuel exhaust assembly chamber by sequentially connecting an air reversing chamber and an exhaust fuel exhaust assembly chamber through which the fuel supply pipe penetrates to the second current collector. connection,
A fuel supply pipe extending from the end face of the exhaust fuel exhaust collecting chamber through the air reversing chamber and the second current collector to the vicinity of the air inlet / outlet end face of the fuel electrode cell is connected to the cell inner surface in the fuel electrode cell. The internal cooling regenerative honeycomb type solid electrolyte fuel cell according to claim 10, wherein a gap is provided between the internal cooling and regenerative honeycomb type solid electrolyte fuel cells.   The internal cooling regenerative honeycomb type solid electrolyte fuel cell according to any one of claims 1 to 11, wherein the air flowing through the cooling air cell and the reaction air flowing through the air electrode cell are reversed in the direction of opposing flow. Solid electrolyte yttria stabilized zirconia (YSZ), scandium-stabilized zirconia (ScSZ), ^O, such as lanthanum gallate-based solid electrolyte or _{C12A7 (12CaO · 7Al 2 O 3} ) -, solids having ionic conductivity of O ^2-, etc. The honeycomb type solid electrolyte fuel cell according to any one of claims 1 to 12, which is an electrolyte or a solid electrolyte that conducts H ⁺ and H ^- ions. Lanthanum gallate solid electrolyte is La _0.8 Sr _0.2 Ga _0.8 Mg _0.2 O _x
La _0.9 Sr _0.1 Ga _0.8 Mg _0.2 O _{x
, La 0.8 Sr 0.2 Ga 0.8 Mg} 0.15 Co 0.05 O x or _{La 0.9 Sr 0.1 Ga 0.8 Mg 0.1} 5Co 0.05 O x) a is claimed Item 14. The internal cooling regenerative honeycomb solid electrolyte fuel cell according to Item 13.

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