JP2014096276A - Fuel cell system and solid oxide fuel cell for use therein and cogeneration system using solid oxide fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell in which thermal stress is reduced without increasing the electrical resistance of an electrode.SOLUTION: A solid oxide fuel cell comprises: a solid electrolyte; an inner electrode and a gas flow path provided in a region surrounded by the solid electrolyte; and an outer electrode provided on the outer surface of the solid electrolyte. The solid oxide fuel cell further includes a plurality of interconnectors connected electrically with the inner electrode and penetrating the solid electrolyte and the outer electrode. The inner electrode or the outer electrode between adjoining interconnectors is provided with a gap of inner electrode or outer electrode, and the gap is provided at the position of symmetric axis of adjoining interconnectors.

Description

  The present invention relates to a fuel cell system, a solid oxide fuel cell used therefor, and a cogeneration system using the solid oxide fuel cell.

  The fuel cell includes an anode (fuel electrode) and a cathode (air electrode) so as to sandwich an electrolyte. Fuel gas is supplied to the anode side, oxidant gas is supplied to the cathode side, and fuel and oxidant are supplied via the electrolyte. Is a power generation device that generates electricity by electrochemically reacting with.

A solid oxide fuel cell (SOFC), which is one type of fuel cell, is a solid having an oxide ion conductivity such as yttria (Y ₂ O ₃ ) or neodymium oxide (Nd ₂ O ₃ ) as an electrolyte. An oxide material is used, an oxide material having a perovskite structure such as La (Sr) MnO or La (Sr) CoO is used for the fuel electrode, and a porous cermet of Ni and an electrolyte material is used for the air electrode. Further, since the SOFC is a fuel cell that operates at a high temperature of 600 to 1000 ° C., it can be hybridized with a gas turbine or the like using exhaust heat, and high power generation efficiency can be expected. However, since it is a high-temperature operation type, there are problems such as cracking and peeling of cell components due to thermal stress. In particular, when a crack occurs in the solid electrolyte, the fuel gas leaks to the air electrode side and burns, resulting in a significant decrease in power generation efficiency. The problem of cracking and peeling due to thermal stress is considered to be largely due to the difference in the coefficient of thermal expansion of the materials constituting the cell.

  In order to solve this problem, conventionally, the second electrolyte layer is disposed between the first electrolyte layer and the fuel electrode, and the third electrolyte layer is disposed between the first electrolyte layer and the air electrode. By increasing the bending strength of the electrolyte layer and the third electrolyte layer, a technique for suppressing the occurrence of cracks, cracks, etc. caused by thermal stress (Patent Document 1), and the electrodes are provided with a myriad of minute cracks. By impregnating and firing this crack with an intermediate material having a lower thermal expansion coefficient than that of the electrode, cracks and delamination occur due to differences in the thermal expansion coefficient of each constituent material while ensuring an effective area as the electrode layer The technique (patent document 2) to prevent is proposed.

JP 2011-192484 A JP 2007-18959 A

  In the method of adding an electrolyte layer as described in Patent Document 1, the thickness of the electrolyte layer increases, so that the ionic conductivity is lowered and the performance is lowered.

  In addition, the crack described in Patent Document 2 causes an increase in electrical resistance, and there is a risk of performance degradation.

  An object of the present invention is to provide a solid oxide fuel cell in which thermal stress is reduced without increasing the electrical resistance of an electrode.

  The solid oxide fuel cell of the present invention has a solid electrolyte, an inner electrode and a gas flow path provided in a region surrounded by the solid electrolyte, and an outer electrode provided on the outer surface of the solid electrolyte. A plurality of interconnectors that are electrically connected to the electrodes and pass through the solid electrolyte and the outer electrodes, and the inner electrode or the outer electrode between the adjacent interconnectors is provided with a gap between the inner electrode and the outer electrode. Is provided at the position of the axis of symmetry between adjacent interconnectors.

  According to the present invention, it is possible to suppress the occurrence of cracks and peeling due to thermal stress without reducing the ionic conductivity of the electrolyte and without increasing the electrical resistance of the electrode.

It is a top view which shows the solid oxide fuel cell of an Example. It is AA sectional drawing of FIG. 1A. It is a figure which shows distribution of the electric current inside an electrode when not providing a slit. It is an electric current distribution figure for examining the position which provides a slit. It is a top view which shows the solid oxide fuel cell of another Example. FIG. 4 is a top view showing dimensions of the solid oxide fuel cell of FIG. 3. It is a front view which shows the dimension of the solid oxide fuel cell of FIG. It is a top view which shows the structure and manufacturing process of the solid oxide fuel cell of an Example. It is a top view which shows the conventional solid oxide fuel cell. It is a top view which shows the structure of the solid oxide fuel cell made into the object of simulation. It is a figure which shows the temperature distribution of the solid oxide fuel cell which is the result of simulation. It is a figure which shows the stress distribution of the solid oxide fuel cell which is the result of the simulation when not providing a slit. It is a figure which shows the stress distribution of the solid oxide fuel cell which is the result of the simulation at the time of providing a slit. It is a top view which shows the modification of a solid oxide fuel cell. It is a top view which shows the other modification of a solid oxide fuel cell. It is sectional drawing which shows the example of the fuel cell module used for a solid oxide fuel cell system. It is a schematic block diagram which shows the example of the cogeneration system using a solid oxide fuel cell system.

  The present invention relates to a fuel cell having an electrolyte, and more particularly to a solid oxide fuel cell.

  The present invention has an inner electrode and a gas channel inside a closed space formed of an electrolyte (solid electrolyte), and has a plurality of interconnectors electrically connected to the outer electrode and the inner electrode on the outer surface of the electrolyte. In a solid oxide fuel cell having a cell, a gap (slit) is provided at a position located in the center between interconnectors on an inner electrode or an outer electrode, and a thermal stress relaxation material is provided in the slit. To do. The thermal stress relieving material provided in the slit can suppress the stress due to the thermal elongation of the electrode and can reduce the influence on the adjacent electrolyte.

  The fuel cell system of the present invention includes a solid oxide fuel cell that is one or a plurality of single cells, a fuel supply pipe, and an air supply pipe. The solid oxide fuel cell includes a solid electrolyte, An inner electrode and a gas flow path provided in a region surrounded by the solid electrolyte, and an outer electrode provided on the outer surface of the solid electrolyte, electrically connected to the inner electrode and penetrating the solid electrolyte and the outer electrode. Having a plurality of interconnectors, the inner electrode or the outer electrode between adjacent interconnectors is provided with a gap between the inner electrode and the outer electrode, and the gap is provided at the position of the symmetry axis of the adjacent interconnector. It is characterized by.

  A cogeneration system of the present invention includes a solid oxide fuel cell unit, a gas turbine, and a generator driven by the gas turbine, and the solid oxide fuel cell unit includes one or a plurality of single cells. A solid oxide fuel cell, a fuel supply pipe, and an air supply pipe. The solid oxide fuel cell includes a solid electrolyte, an inner electrode provided in a region surrounded by the solid electrolyte, and a gas flow. A plurality of interconnectors that are electrically connected to the inner electrode and pass through the solid electrolyte and the outer electrode, between the adjacent interconnectors, and a path and an outer electrode provided on the outer surface of the solid electrolyte. The inner electrode or the outer electrode is provided with a gap between the inner electrode or the outer electrode, and the gap is provided at the position of the symmetry axis of the adjacent interconnector.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1A schematically shows a solid oxide fuel cell (single cell) having a flat cylindrical shape. Moreover, FIG. 1B is AA sectional drawing of FIG. 1A.

  In this figure, a solid oxide fuel cell 100 (single cell) has a cylindrical shape (flat cylindrical shape), an inner anode 101, an outer cathode 103, and a solid electrolyte 102 disposed therebetween. including. Inside the anode 101 is a fuel gas flow path 120.

  An interconnector 104 is connected to the anode 101. The interconnector 104 is exposed to the outside through a window 110 provided in the solid electrolyte 102 and the cathode 103. The interconnector 104 is a connector for taking out the current of the anode 101. An insulating material 105 is installed between the interconnector 104 and the cathode 103 (a gap between the windows 110) so that they are not electrically connected.

  An oxidant gas such as air is supplied to the outer surface of the cathode 103. The oxidant gas becomes oxygen ions at the cathode 103, and the oxygen ions pass through the solid electrolyte 102 and react with hydrogen as a fuel at the anode 101 to generate electric power. The electric power generated by the anode 101 can be taken out as a current through the interconnector 104 to be connected.

  In this figure, gaps 106 and 107 (hereinafter also referred to as slits) of the cathode 103 are provided in the direction of cutting the cylindrical single cell, and a thermal stress relieving material is installed in the gaps 106 and 107. The gaps 106 and 107 can also be called electrode breaks.

  In this figure, the cell shape is a flat cylindrical shape, but the present invention is not limited to this, and may be a flat plate shape, a cylindrical shape, an elliptical shape, a rectangular parallelepiped shape, a cubic shape, or the like. . In the single cell shown in this figure, the anode 101 is formed on the inner side and the cathode 103 is formed on the outer side. However, the cathode 103 may be formed on the inner side and the anode 101 may be formed on the outer side.

  FIG. 2A shows the current distribution inside the electrode when no slit is provided. In other words, the direction and magnitude of the current in the anode 101 is represented by a vector and partially enlarged.

  From this figure, it can be seen that the current amount is large (the current density is low) in the peripheral portion (near portion) where the anode 101 and the interconnector 104 are in contact. On the other hand, the amount of current is small in the central portion of the region between the adjacent interconnectors 104.

  In the enlarged view, the end of the long axis of the interconnector 104 is shown. In the central portion (on the line connecting A and A ′) between the major axes of adjacent interconnectors 104, the direction of current is parallel to the major axis. On the other hand, in the central portion (on the line connecting B and B ′) between the long-axis ends of the adjacent interconnectors 104, the vector indicating the current flow is dotted, and almost no current flows. Recognize.

  FIG. 2B is a current distribution diagram for examining the position where the slit is provided. The current distribution is the same as in FIG. 2A.

  In FIG. 2B, line segments J, K, L, and M indicate candidate positions for providing slits.

  At the position of the line segment J, the direction of the current is parallel to the major axis of the interconnector 104 as described above. Therefore, even if the slit is provided at the position of the line segment J, the current is not inhibited and the electric resistance value in the anode 101 is not affected.

  The line segment J overlaps the position of the axis of symmetry when two adjacent interconnectors 104 (upper and lower in the figure) are in a line-symmetrical position.

  At the position of the line segment K, almost no current flows as described above. Therefore, even if the slit is provided at the position of the line segment K, the current is not inhibited and the electric resistance value in the anode 101 is not affected.

  The line segment K overlaps the position of the axis of symmetry when two adjacent interconnectors 104 (left and right in the figure) are in a line-symmetrical position.

  On the other hand, when the slits are provided at the positions of the line segments L and M, the current is inhibited and the electric resistance is increased.

  Therefore, when two adjacent interconnectors 104 are in a line-symmetrical position, an increase in the electrical resistance value in the anode 101 can be suppressed by providing a slit at the position of the symmetrical axis (symmetrical axis). Furthermore, by filling the slit with a thermal stress relaxation material, an increase in electrical resistance value can be suppressed, and thermal stress caused by differences in thermal expansion coefficients of the anode, the solid electrolyte, the cathode, and the like can be reduced. Moreover, even if there is no thermal stress relaxation material, the effect of the present invention can be obtained.

  As can be seen from FIGS. 2A and 2B, since the current density is low in the vicinity of the position of the symmetry axis, not only when a slit is provided at the position of the symmetry axis but also in the vicinity of the position of the symmetry axis. A substantially similar effect can be obtained when a slit is provided in the case. Therefore, even when a slit is provided in the vicinity of the position of the symmetry axis, it can be said that the idea of the present invention has been realized.

  FIG. 3 is a top view showing a solid oxide fuel cell according to another embodiment.

  In this figure, a solid oxide fuel cell 200 (single cell) has a cylindrical shape (flat cylindrical shape), an inner anode 201, an outer cathode 203, and a solid electrolyte 202 disposed therebetween. including.

  An interconnector 204 is connected to the anode 201. The interconnector 204 is exposed to the outside through a window 206 provided in the solid electrolyte 202 and the cathode 203. The interconnector 204 is a connector for taking out the current of the anode 201. An insulating material 205 is installed between the interconnector 204 and the cathode 203 (a gap between the windows 206) so that they are not electrically connected.

  In this figure, gaps 207, 208, 209, and 210 (slits) of the cathode 203 are provided in a direction in which a cylindrical single cell is cut into rounds. In these gaps 207, 208, 209, 210, a thermal stress relaxation material is installed. In this embodiment, the widths of the gaps 207, 208, 209, and 210 are 0.5 mm, respectively. Further, the cathode 203 is provided with gaps 211 and 212 parallel to the major axis of the interconnector 204. Thermal stress relaxation materials are also installed in these gaps 207, 208, 209, and 210 (slits). In the present embodiment, the gaps 211 and 212 each have a width of 1.0 mm.

  In the present embodiment, the inner anode 201 is also provided with gaps 251 and 252 (slits) parallel to the long axis of the interconnector 204.

  4A is a top view showing dimensions of the solid oxide fuel cell of FIG. FIG. 4B is a front view showing dimensions of the solid oxide fuel cell of the example.

  As shown in FIG. 4A, the solid oxide fuel cell 400 has a width of 57 mm and a length of 260 mm. The thickness of the solid oxide fuel cell 400 is 2 mm as shown in FIG. 4B.

  In FIG. 4A, reference numeral 401 denotes an inlet portion of the fuel gas flow path formed along the inner anode 411 formed in a cylindrical shape, and reference numeral 402 denotes an outlet portion.

  The alternate long and short dash lines B and C perpendicular to the fuel gas flow path are the slit installation positions, and overlap the positions of the symmetrical axes of the interconnectors 404 adjacent to each other in the major axis direction of the interconnectors 404. In the vicinity of the inlet portion 401 and the outlet portion 402, slits are provided in parallel with the alternate long and short dash lines B and C at the positions of alternate long and short dashed lines A and D, respectively. The length between A-B, B-C, and C-D is 80.5 mm, respectively.

  On the other hand, alternate long and short dash lines E and F shown along the fuel gas flow path are the positions where the slits are installed, and overlap the positions of the symmetrical axes of the adjacent interconnectors 404. The widths of the three regions separated by the alternate long and short dash lines E and F are each 19.0 mm.

  It is desirable to provide a thermal stress relaxation material in the slit. Thereby, an increase in electrical resistance can be suppressed without disturbing the current.

  FIG. 5 shows the configuration and manufacturing process of the solid oxide fuel cell of FIG.

  A solid oxide fuel cell uses an inner electrode installed inside a cylindrical solid electrolyte or a porous body installed in an inner channel as a support.

  Hereinafter, a description will be given with reference to FIG.

  The inner flow path 501 installed inside the solid electrolyte is a hollow portion or a porous layer of the inner electrode.

In the case of a porous layer, materials include silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), zirconia (ZrO ₂ ), alumina (Al ₂ O ₃ ), mullite (3Al ₂ O ₃ .SiO ₂ ). , using excellent fine ceramics in thermal shock resistance, such as cordierite _{(2MgO · 2Al 2 O 3 ·} 5SiO 2). Since this material has strength as a support, the porosity is desirably 30% to 95%. Here, a silicon nitride ceramic porous body having a thickness of 1.9 mm, a width of 75 mm, and a length of 260 mm was used in order to provide a function as a support substrate.

  In step 1, a sintering aid is added to and mixed with silicon nitride ceramic powder, incinerated short fiber pore-forming material powder is added, and a molded body is produced by water-based slurry casting. The inner flow path 501 which is a silicon nitride ceramic porous body was obtained by heating and removing the dispersed short fibers by incineration. The silicon nitride ceramic porous body has a fibrous through-hole and a predetermined strength, and its porosity is 85%.

  Next, in Step 2, an anode layer 502 in which a thermal stress relaxation material was installed in the slit around the inner flow path 501 was produced.

  The anode layer 502 is a composite electrode having a composite material (Ni—ScSZ cermet) of Ni and a ceramic material. In accordance with the slit installation described in the description of FIG. 4, a slit-shaped mask is formed so that a slit having a width of 0.5 mm in the flow channel direction (long axis direction) and a width of 1 mm in the direction orthogonal to the long axis is formed. Was used for screen printing. Thereby, the anode constituent material processed into a slurry was formed around the inner flow path 501 so as to have a thickness of 50 μm. Thereafter, the same material as the solid electrolyte 202, for example, a slurry-like solid electrolyte constituent material of yttrium-stabilized zirconia (YSZ) is installed as a thermal stress relaxation material in the slit portion (concave portion), and around the inner flow path 501, An anode layer 502 in which a thermal stress relaxation material was installed in the slit was produced.

Here, as the thermal stress relaxation material, low thermal expansion ceramics having a thermal expansion coefficient of 10 × 10 ⁻⁶ or less (2 significant digits), for example, cordierite, aluminum titanate, zirconium phosphate, or the like may be used. Further, it may be the same material as the porous layer used for the inner channel 501, for example, a silicon nitride ceramic porous body. The thermal stress relaxation material may be a cermet material having high oxidation resistance at high temperatures, such as TiN-WC cermet, Cr ₃ C ₂ -Ni-W cermet, Al ₂ O ₃ cermet, and these cermets. Ceramic material coated with In addition, porous materials of these materials may be used. By setting the Young's modulus to a value of 100 × 10 ⁹ N / m ² or less (2 significant digits) by controlling the porosity, elasticity is given. The thermal strain may be easily absorbed.

Next, in Step 3, a solid electrolyte layer 503 was formed around the anode layer 502. This solid electrolyte layer 503 is a slurry-like solid electrolyte constituent material of a solid oxide material having oxide ion conductivity such as yttria (Y ₂ O ₃ ) or neodymium oxide (Nd ₂ O ₃ ) having a thickness of 10 μm. It was formed by a screen printing method using a mask having a shape in which a window for installing an interconnector was opened. Thereafter, the laminate was sintered at a temperature of 1400 ° C. for a predetermined time (for example, 1 hour) and sintered to obtain a laminated sintered body of the anode layer 502 and the solid electrolyte layer 503.

  In Step 4, as in the anode layer 502, a cathode layer 504 in which a thermal stress relaxation material was installed in the slit around the laminated sintered body of the anode layer 502 and the solid electrolyte layer 503 produced in Step 3 was produced. .

  For the cathode layer 504, an oxide material having a perovskite structure such as La (Sr) MnO or La (Sr) CoO was used. In accordance with the slit installation described in the explanation of FIG. 4, the slit shape and the interconnector are installed so that a slit having a width of 0.5 mm in the flow path direction (long axis direction) and a width of 1 mm in the direction orthogonal to the long axis is configured. Screen printing was performed using a mask having a shape in which a window for opening the window was opened. Thereby, the cathode constituent material processed into a slurry was formed around the laminated sintered body produced in Step 3 so as to have a thickness of 50 μm. This was held at a high temperature of 1200 ° C. for a predetermined time (for example, 1 hour) and sintered to obtain a laminated sintered body of the cathode layer 504.

In Step 5, an interconnector made of a Fe-22Cr-based ferritic alloy, a SrTiO ₃ perovskite material or a lanthanum chromide material, and alumina (Al ₂ O ₃ ), silica (SiO ₂ ) or calcia (CaO). ) Is formed of a crystallized glass material having a main component, and is maintained at a high temperature state at a temperature of 950 ° C. for a predetermined time (for example, 1 hour) to crystallize the insulating material and closely adhere to a gap between windows, A solid oxide fuel cell 505 was obtained.

  Next, the effect of the present invention will be examined by analysis using numerical simulation.

  The object of analysis is the solid oxide fuel cell 200 of FIG. Further, in order to clarify the effect of the invention, the solid oxide type of FIG. 6 is a case where no slit is provided in the anode 201 and the cathode 203 and no thermal stress relaxation material is provided, that is, no thermal stress relaxation means is provided. In the case of the fuel cell 600, analysis by numerical simulation was performed under the same conditions.

  For the numerical simulation, a commercially available simulator software, a thermal fluid analysis program FLUENT manufactured by ANSYS and a structure analysis program MECHANICAL were used.

  Table 1 shows physical property values of materials used for the solid oxide fuel cell.

  The thermal stress relieving material fills the slit (the concave portion of the slit) when the slit is provided. Here, the same material as the solid electrolyte smaller than the thermal expansion coefficient of the electrode was used. By disposing a material having a small coefficient of thermal expansion in the slit in the electrode, distortion due to thermal expansion of the electrode can be reduced, and tensile stress to the adjacent solid electrolyte can be reduced.

  The analysis conditions in the numerical simulation are as follows.

The operating current density was 0.6 A / cm ² , the fuel gas was a mixed gas of hydrogen and nitrogen, and the oxidant gas was air. The fuel utilization rate was 90%, the oxygen utilization rate was 20%, and the inlet temperature of the fuel gas and air was 700 ° C.

  As shown in FIG. 7A, the fuel gas and the air flowing into the solid oxide fuel cell 801 are opposed to each other. The wall was assumed to be insulated.

  First, the temperature of the solid oxide fuel cell 801 was analyzed using the thermal fluid analysis program FLUENT.

  FIG. 7B is an analysis result of the solid oxide fuel cell 600 of FIG. 6 and shows the temperature distribution of the solid oxide fuel cell 600.

  From FIG. 7B, it can be seen that the temperature on the upstream side of the fuel gas channel reaches about 1000 ° C.

  Based on this temperature distribution, the structural stress analysis program MECHANICAL was used to calculate the thermal stress generated in the solid oxide fuel cell.

  FIG. 7C shows the stress distribution of the solid electrolyte portion in the solid oxide fuel cell 600 of FIG. 6 in which no slit is provided. FIG. 7D shows the stress distribution of the solid electrolyte portion in the solid oxide fuel cell 200 of FIG. 3 having a configuration in which a slit is provided and the slit is filled with a thermal stress relaxation material.

  As a result of analysis using this numerical simulation, the maximum stress was 478 MPa in the solid oxide fuel cell 200 (with slits) in FIG. On the other hand, in the solid oxide fuel cell 600 (without slits) shown in FIG. 6, the maximum stress was 508 MPa. Therefore, it was found that by providing the slit and the thermal stress relaxation material, the thermal stress can be reduced by about 6% as an effect of the present invention.

  FIG. 8 is a top view showing a modification of the solid oxide fuel cell.

  In the solid oxide fuel cell 900, in the solid oxide fuel cell 100 of FIG. 1A, an interconnector 912 having a longer axis than the interconnector 911 is provided in a portion 901 near the fuel gas inlet 902, and adjacent interconnectors 912 are provided. A slit 913 perpendicular to the major axis is disposed between the two. The width of the slit 913 (gap) is 1.2 mm, which is 5 to 20% wider than the widths of the other slits 914. Thereby, about the part 901 near the fuel gas inlet 902, the thermal stress relaxation material with which the recessed part of the slit 913 and the slit 913 is filled can be increased.

  From the analysis results shown in FIGS. 7B to 7D, it can be seen that in the portion 901 close to the fuel gas inlet 902, the cell temperature increases and the thermal stress of the solid electrolyte increases. Therefore, the effect of suppressing thermal stress can be increased by finely dividing the interconnector provided in the portion 901 and increasing the number of slits 913 and thermal stress relaxation materials.

  FIG. 9 is a top view showing another modification of the solid oxide fuel cell.

  In this figure, the solid oxide fuel cell 1000 has a long axis extending from an interconnector 1004 adjacent in the direction perpendicular to the long axis, with reference to the arrangement of the interconnector 104 of the solid oxide fuel cell 100 shown in FIG. 1A. The gaps 1001 and 1002 are arranged at positions shifted in the direction and bent. Thereby, the area | region (area) which can install a thermal stress relaxation material increases, and the effect which suppresses a thermal stress can be enlarged.

  It is desirable that these gaps 1001 and 1002 do not overlap with the gaps provided on the back surface of the solid oxide fuel cell 1000. This is to prevent the entire solid oxide fuel cell 1000 from breaking along the gap.

  FIG. 10 is a cross-sectional view showing an example of a fuel cell module used in a solid oxide fuel cell system (solid oxide fuel cell unit).

  The fuel cell module 1100 shown in the figure is formed by connecting four solid oxide fuel cells 1101 (single cells) in series and connecting these in parallel in two rows. The fuel cell module 1100 is sandwiched between collectors 1102 and 1103 and enclosed in a container 1104.

  In this figure, the fuel cell module 1100 is constituted by a total of eight solid oxide fuel cells 1101, but the present invention is not limited to this. A fuel cell module may be constituted by one solid oxide fuel cell.

  FIG. 11 is a schematic configuration diagram illustrating an example of a cogeneration system using a solid oxide fuel cell unit.

  In this figure, the cogeneration system 1200 includes a compressor 1202, a solid oxide fuel cell unit 1204, a gas turbine 1206, and a generator 1207.

  The compressor 1202 is configured to rotate coaxially with the gas turbine 1206. The generator 1207 and the compressor 1202 are driven by the rotation of the gas turbine 1206. The compressor 1202 sucks outside air (air) from the pipe 1201 and sends high-pressure air to the solid oxide fuel cell unit 1204 through the pipe 1203. The higher the air pressure, the more efficient the solid oxide fuel cell unit 1204 is.

  Further, fuel gas is supplied to the solid oxide fuel cell unit 1204 via a pipe 1205, and electricity is generated by a reaction between the fuel gas and air. The high-pressure exhaust gas generated in the solid oxide fuel cell unit 1204 is sent to the gas turbine 1206 to drive the gas turbine 1206. Exhaust gas that has passed through the gas turbine 1206 is discharged into the atmosphere via a pipe 1208.

  Although not shown in the drawing, it is possible to further generate power by heating the water with the heat of the exhaust gas that has passed through the gas turbine 1206 to generate water vapor and driving the steam turbine.

  The configuration of the cogeneration system 1200 is not limited to that shown in the figure, and can be applied to various combinations.

  100, 1101: Solid oxide fuel cell, 101: Anode, 102: Solid electrolyte, 103: Cathode, 104: Interconnector, 105: Insulating material, 106, 107, 207, 208, 209, 210, 211, 212: Gap, 110: Window, 120: Fuel gas flow path, 1100: Fuel cell module, 1102, 1103: Collector, 1104: Container, 1200: Cogeneration system, 1202: Compressor, 1204: Solid oxide fuel cell unit, 1206: Gas turbine, 1207: Generator.

Claims (16)

  A solid oxide fuel cell that is one or a plurality of single cells, a fuel supply pipe, and an air supply pipe, the solid oxide fuel cell being surrounded by a solid electrolyte and the solid electrolyte A plurality of inner electrodes and gas passages provided in the region and outer electrodes provided on the outer surface of the solid electrolyte, and electrically connected to the inner electrode and penetrating the solid electrolyte and the outer electrode; The inner electrode or the outer electrode between the adjacent interconnectors is provided with a gap between the inner electrode or the outer electrode, and the gap is a symmetrical axis of the adjacent interconnector. A fuel cell system provided at a position.   The fuel cell system according to claim 1, wherein a thermal stress relaxation material is installed in the gap. The thermal stress relaxation material is formed of a material satisfying one or both of a thermal expansion coefficient of 10 × 10 ⁻⁶ or less and a Young's modulus of 100 × 10 ⁹ N / m ² or less. 3. The fuel cell system according to 2.   2. The fuel cell system according to claim 1, wherein the width of at least the gap closest to the fuel gas inlet is 5 to 20% wider than the width of the other gap.   The fuel cell system according to claim 1, wherein the solid oxide fuel cell has a flat cylindrical shape.   A solid electrolyte, an inner electrode and a gas flow path provided in a region surrounded by the solid electrolyte, and an outer electrode provided on an outer surface of the solid electrolyte, and electrically connected to the inner electrode A plurality of interconnectors penetrating the solid electrolyte and the outer electrode, and the inner electrode or the outer electrode between the adjacent interconnectors is provided with a gap between the inner electrode or the outer electrode, and the gap Is provided at the position of the axis of symmetry of the adjacent interconnectors.   The solid oxide fuel cell according to claim 6, wherein a thermal stress relaxation material is installed in the gap. The thermal stress relaxation material is formed of a material satisfying one or both of a thermal expansion coefficient of 10 × 10 ⁻⁶ or less and a Young's modulus of 100 × 10 ⁹ N / m ² or less. 8. The solid oxide fuel cell according to 7.   7. The solid oxide fuel cell according to claim 6, wherein the width of at least the gap closest to the fuel gas inlet is 5 to 20% wider than the width of the other gap.   7. The solid oxide fuel cell according to claim 6, wherein the overall shape is a flat cylindrical shape.   A solid oxide fuel cell unit comprising a solid oxide fuel cell unit, a gas turbine, and a generator driven by the gas turbine, wherein the solid oxide fuel cell unit is one or a plurality of single cells. The solid oxide fuel cell includes a solid electrolyte, an inner electrode and a gas flow path provided in a region surrounded by the solid electrolyte, and the solid electrolyte. A plurality of interconnectors that are electrically connected to the inner electrode and pass through the solid electrolyte and the outer electrode, and between the adjacent interconnectors. The inner electrode or the outer electrode is provided with a gap between the inner electrode or the outer electrode, and the gap is provided at the position of the axis of symmetry of the adjacent interconnector. Generation system.   The cogeneration system according to claim 11, further comprising a compressor.   The cogeneration system according to claim 11, wherein a thermal stress relaxation material is installed in the gap. The thermal stress relaxation material is formed of a material satisfying one or both of a thermal expansion coefficient of 10 × 10 ⁻⁶ or less and a Young's modulus of 100 × 10 ⁹ N / m ² or less. 13. The cogeneration system according to 13.   12. The cogeneration system according to claim 11, wherein the width of at least the gap closest to the fuel gas inlet is 5 to 20% wider than the width of the other gap.   12. The cogeneration system according to claim 11, wherein the solid oxide fuel cell has a flat cylindrical shape.

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