JP2006100212A - Solid oxide type fuel cell and production method for solid oxide type fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide type fuel cell allowing reduction of diffusion resistance of fuel gas in a substrate pipe without impairing strength of the substrate pipe, and allowing efficient removal of water vapor generated from the inner surface of the substrate pipe. <P>SOLUTION: This solid oxide type fuel cell has: the cylindrical and porous substrate pipe 1 having an inner wall 2b formed in an unevenness face and an outer wall 2a formed in a cylindrical face; and a cell provided on the surface of the outer wall 2a. Preferably, a recessed part 14a of the inner wall 2b includes a groove extending to an axis E direction of the cylindrical face. The recessed part can include a groove spiral with respect to the axis of the cylindrical face. Preferably, a projecting part 12a of the inner wall 2b continuously extends to the axis E direction of the cylindrical face. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid oxide fuel cell and a method for manufacturing a solid oxide fuel cell, and more particularly to a solid oxide fuel cell having improved performance and efficiency and a method for manufacturing a solid oxide fuel cell.

  2. Description of the Related Art Solid oxide fuel cells that generate electricity through an electrochemical reaction between a fuel gas reformed by reacting hydrocarbons with water vapor and oxygen have been known. The solid oxide fuel cell includes a cell composed of an air electrode, a solid oxide electrolyte membrane, and a fuel electrode. Oxygen is supplied to the air electrode, and fuel gas is supplied to the fuel electrode. Oxygen supplied to the air electrode is ionized and permeates through the electrolyte membrane and reaches the fuel electrode. Electricity is generated by taking out a potential difference generated between the fuel electrode and the air electrode due to an electrochemical reaction between oxygen and fuel gas that has reached the fuel electrode.

  An example of a conventional solid oxide fuel cell is disclosed in Japanese Patent Laid-Open No. 10-134825. In this conventional solid oxide fuel cell, a plurality of cells are electrically connected via an interconnector on a cylindrical porous substrate tube having a certain thickness. In each cell, a fuel electrode, an electrolyte membrane, and an air electrode are stacked in this order on a base tube.

Further improvement in performance / efficiency is desired for solid oxide fuel cells.
The fuel gas used as the fuel for the cell reaction flows inside the base tube, diffuses through the pores of the base tube, and reaches the fuel electrode. Therefore, in order to improve the efficiency of the solid oxide fuel cell, it is important to suppress the diffusion resistance of the fuel gas in the base tube and improve the gas permeability. A technique for suppressing the diffusion resistance of fuel gas and improving gas permeability is desired.

  The water produced by the cell reaction diffuses through the pores as water vapor from the fuel electrode to the inside of the base tube. The water vapor reaching the inner surface of the base tube is removed from the fuel gas flowing inside the base tube. However, the concentration of the water vapor tends to increase in the vicinity of the inner surface. That is, the concentration of water vapor near the opening of the pore exposed on the inner surface is increased. In that case, the fuel gas is prevented from entering the pores, and the amount of the fuel gas diffusing through the pores is reduced. As a result, cell efficiency is reduced. A technique for efficiently removing water vapor from the inner surface of the base tube is desired.

JP-A-10-134825

  Another object of the present invention is to provide a solid oxide fuel cell having a low diffusion resistance of fuel gas in the base tube and a method for manufacturing the solid oxide fuel cell.

  Still another object of the present invention is to provide a solid oxide fuel cell capable of efficiently removing water vapor from the inner surface of a substrate tube and a method for producing the solid oxide fuel cell.

  An object of the present invention is to provide a solid oxide fuel cell and a solid oxide fuel cell that have low diffusion resistance of fuel gas in the base tube or can efficiently remove water vapor from the inner surface of the base tube while maintaining the strength of the base tube It is to provide a method for manufacturing a physical fuel cell.

  Hereinafter, means for solving the problem will be described using the numbers and symbols used in the best mode for carrying out the invention. These numbers and symbols are added in parentheses in order to clarify the correspondence between the description of the claims and the best mode for carrying out the invention. However, these numbers and symbols should not be used for interpreting the technical scope of the invention described in the claims.

In order to solve the above problems, a solid oxide fuel cell (10) of the present invention is a cylindrical porous substrate tube having an inner wall (2b) forming an uneven surface and an outer wall (2a) forming a cylindrical surface. (1 / 1a / 1b) and a cell (6) provided on the surface of the outer wall (2a).
Due to the unevenness, the base tube is provided with a thick part having a thick wall and a thin part having a thinner thickness than the thick part by the outer wall and the inner wall. The diffusion resistance of the fuel gas can be reduced in the thin part. The strength of the base tube can be maintained at the thick part. It is possible to efficiently remove water vapor from the inner surface of the base tube by disturbing the flow of the fuel gas with the unevenness.

In the above solid oxide fuel cell, the recess (14 (a, b, c, d)) of the inner wall (2b) preferably includes a groove extending in the axis (E) direction of the cylindrical surface.
The groove can reduce the diffusion resistance of the fuel gas.

In the above solid oxide fuel cell, the concave portion (24 (a, b, c, d) / 34 (a, b, c, d), 36 (a, b, c, d)) of the inner wall (2b)) Preferably includes a groove having a first helical shape with respect to the axis (Ea / Eb) of the cylindrical surface.
By having a spiral shape, the flow of the fuel gas can be further disturbed.

In the above solid oxide fuel cell, the recesses (34 (a, b, c, d), 36 (a, b, c, d)) have the first spiral shape with respect to the axis (Eb) of the cylindrical surface. It is preferable that the groove | channel which has a 2nd spiral shape different from is included.
Furthermore, by having another spiral shape, the flow of the fuel gas can be further disturbed.

In the solid oxide fuel cell, the groove cross section preferably includes at least a part of a circle, an ellipse, and a polygon.
Such a cross-sectional shape can maintain strength more stably than an irregular shape.

In the above solid oxide fuel cell, the convex portion (12 (a, b, c, d) / 22 (a, b, c, d) / 32 (a, b, c, d) of the inner wall (2b) ) Preferably extend continuously in the direction of the axis (E / Ea / Eb) of the cylindrical surface.
The strength can be appropriately maintained by the continuous convex portion.

In the solid oxide fuel cell, the base tube (1 / 1a / 1b) is preferably made of ceramics.
Since the substrate tube is made of ceramics, it can be used stably even under extremely high temperature conditions where the solid oxide fuel cell is operated.

In the above solid oxide fuel cell, it is preferable that the fuel gas passes through the base tube (1 / 1a / 1b).
Since water vapor is generated on the side through which the fuel gas passes, it can be effectively used by removing it.

In the above solid oxide fuel cell, the cross section perpendicular to the axis (E / Ea / Eb) of the cylindrical surface of the substrate tube (1 / 1a / 1b) intersects the axis (E / Ea / Eb) perpendicularly. It is preferably symmetrical with respect to the line and symmetrical with respect to the axis (E / Ea / Eb).
With such a shape, the stress can be dispersed almost uniformly, making it difficult to break.

  In order to solve the above-mentioned problems, the method for producing a solid oxide fuel cell according to the present invention comprises: (a) a base tube material so that the outer wall (2a) forms a cylindrical surface and the inner wall (2b) forms an uneven surface. Extruding to form a cylindrical tube; and (b) joining a fuel electrode material to the outer surface of the cylindrical tube, joining an electrolyte material to the outer surface of the fuel electrode material, and adjoining the joined Joining the interconnector material between the electrolyte material and the fuel electrode material; and (c) firing the base tube material, the fuel electrode material, the electrolyte material, and the interconnector material. .

  In the method for manufacturing a solid oxide fuel cell, the step (b) preferably includes a step (b1) of joining an air electrode material to the outer surface of the electrolyte material. The step (c) preferably includes a step (c1) of firing the air electrode material in addition to the base tube material, the fuel electrode material, the electrolyte material, and the interconnector material.

  The method for manufacturing a solid oxide fuel cell further includes (d) a step of bonding an air electrode material to the outer surface of the fired electrolyte material, and (e) a step of firing the air electrode. It is preferable.

  In the method of manufacturing a solid oxide fuel cell, the step (a) includes: (a1) the concave portion (14 (a, b, c, d)) of the inner wall (2b) has an axis (E / It is preferable to include a step of extruding the base tube material so as to include a groove extending in the direction of Ea / Eb).

  In the method for producing a solid oxide fuel cell, the step (a) includes (a2) a recess (24 (a, b, c, d) / 34 (a, b, c, d) on the inner wall (2b). , 36 (a, b, c, d)) comprises extruding the substrate tube material so as to include a groove having a first helical shape with respect to the cylindrical surface axis (E / Ea / Eb). Is preferred.

  In the method for manufacturing a solid oxide fuel cell, the step (a2) includes (a3) recesses (34 (a, b, c, d), 36 (a, b, c, d) on the inner wall (2b). Preferably includes a step of extruding the base tube material so as to further include a groove having a second helical shape different from the first helical shape with respect to the cylindrical surface axis (E / Ea / Eb). .

  In the solid oxide fuel cell of the present invention, by providing an uneven surface on the inner wall of the base tube, the diffusion resistance of the fuel gas in the base tube is reduced and the inner surface of the base tube is reduced without impairing the strength of the base tube. Water vapor can be efficiently removed from the water.

  Embodiments of a solid oxide fuel cell and a solid oxide fuel cell manufacturing method according to the present invention will be described below with reference to the accompanying drawings. Here, a solid oxide fuel cell will be described, but it can also be applied to a water electrolysis cell by reversing the reaction.

(First embodiment)
First, a first embodiment of the solid oxide fuel cell of the present invention will be described.

  FIG. 1 is a cross-sectional view showing the configuration of a first embodiment of a solid oxide fuel cell 10 of the present invention. The solid oxide fuel cell 10 includes a base tube 1, a plurality of cells 6, and a plurality of interconnectors 7. The base tube 1 is a cylinder made of ceramics. Here, it is a substantially cylindrical type. The outer wall 2a has a cylindrical surface. The inner wall 2b has an uneven surface including a recess as a dent and a protrusion as a protrusion. The uneven surface will be described later. The plurality of cells 6 are provided on the surface of the outer wall 2 a of the base tube 1. The interconnector 7 electrically connects adjacent cells 6 in series.

  The cell 6 includes a fuel electrode 3, an electrolyte membrane 4, and an air electrode 5. The fuel electrode 3, the electrolyte membrane 4 and the air electrode 5 are laminated on the outer wall 2a in this order. The fuel electrode 3 of one cell 6 and the air electrode 5 of another cell 6 adjacent thereto are electrically connected by an interconnector 7. The base tube 1, the fuel electrode 3, and the air electrode 5 are porous. The electrolyte membrane 4 and the interconnector 7 are dense membranes that do not allow gaseous gases to pass through.

The main component of the base tube 1 is exemplified by a zirconia (ZrO ₂ ) -based composite oxide such as ZrO ₂ —CaO (CSZ). Since the inner wall 2b is an uneven surface, the base tube 1 has a thick portion and a thin portion. Their thickness is set according to the required strength. In the present embodiment, for example, the maximum thickness of the thick portion is 3 mm. The minimum thickness of the thin portion is, for example, 1 mm.

  The main component of the fuel electrode 3 is exemplified by a mixture of nickel oxide such as NiO—YSZ and other metal oxides. The thickness of the fuel electrode 3 is set based on the required electric resistance. From the viewpoint of electrical resistance, it is preferably 100 μm or more, more preferably 500 μm or more. On the other hand, 1.0 mm or less is preferable from the viewpoint of gas diffusion resistance.

The main component of the electrolyte membrane 4 is exemplified by a zirconia (ZrO ₂ ) -based oxide such as ZrO ₂ —Y ₂ O ₃ (YSZ). The thickness of the electrolyte membrane is preferably as thin as possible, but is preferably 10 μm or more, which is difficult to produce pinholes and cracks in production. On the other hand, 0.2 mm or less is preferable from the surface of electrical resistance. More preferably, it is 0.1 mm or less.

The main component of the air electrode 5 is exemplified by a lanthanum manganate (LaMnO ₃ ) -based oxide such as LaSrMnO ₃ . The thickness of the air electrode 5 is set based on the required electric resistance. From the surface of electrical resistance, 0.2 mm or more is preferable, and more preferably 0.3 mm or more. On the other hand, it is preferably 2 mm or less, more preferably 1.0 mm or less from the surface of gas diffusion resistance.

  The main component of the interconnector 7 is exemplified by titanium oxide. The thickness of the interconnector 7 is set based on the required electric resistance. From the viewpoint of gas tightness and electric resistance, 20 μm or more is preferable. 100 μm or less is preferable in view of the shape relationship with other layers.

  Next, the substrate tube 1 in the first embodiment of the solid oxide fuel cell of the present invention will be further described. FIG. 2 is a cross-sectional view showing the configuration of the base tube 1 in the first embodiment of the solid oxide fuel cell of the present invention. The left side shows a cross section perpendicular to the axis E of the cylindrical surface of the outer wall 2a, and the right side shows a cross section including the axis E and parallel to the axis E.

  Referring to the drawing on the right side, a convex portion 12a (thick portion) and a concave portion 14a (thin portion) are arranged in order on the inner wall 2b of the base tube 1 along the circumferential direction of the cylindrical surface of the outer wall 2a. Yes. Each has a constant thickness in the circumferential direction. With reference to the left figure, the convex portion 12a and the concave portion 14a extend in the direction of the axis E in parallel with the axis E. The cross-sectional shape of the recess 14a is a square groove along the cylindrical surface.

  By providing the recess 14a (thin portion), gas diffusion resistance when the fuel gas in the base tube 1 diffuses to the fuel electrode can be reduced. Thereby, cell efficiency can be improved. By providing the convex portion 12a (thick portion), strength reduction due to the thin portion can be suppressed, and the strength of the base tube 1 can be maintained within a predetermined range. The thickness ta1 of the base tube 1 at the convex portion 12a, the width A1 of the convex portion 12a (width along the circumference of the cylindrical surface), the thickness tb1 of the base tube 1 at the concave portion 14a, and the width B1 of the concave portion 14a (circumference of the cylindrical surface) And the height H1 of the convex portion 12a with respect to the concave portion 14a is set based on the efficiency required for the cell and the required strength.

  By providing the convex portion 12a and the concave portion 14a, it is possible to further disturb the flow of the fuel gas and stir the region having a high water vapor concentration near the surface of the inner wall 2b with the fuel gas. Therefore, water vapor near the surface can be efficiently removed, and the water vapor concentration can be reduced. Thereby, the efficiency of a cell can be improved.

  The width A1 is preferably smaller than the width B1. Thereby, gas diffusion resistance can be reduced more. The sum of the width A1 and the width B1 (the period between the convex portion 12a and the concave portion 14a) is preferably within a predetermined range. If it is too small, it will be difficult for the fuel gas to reach the recess 14a, and if it is too large, a thick portion having a relatively large gas diffusion resistance will continue, and the cell efficiency will decrease.

  The height H1 is preferably within a predetermined range. If the height H1 is too low (the thick portion is too thin), the difference between the convex portion 12a and the concave portion 14a becomes small, and the above effects cannot be obtained. On the other hand, even if the height H1 is too high (the thick portion is too thick), the strength of the thick portion and the thin portion becomes too large, and the weak portion is easily broken. In addition, the diffusion of the fuel gas to the cells on the outer wall 2a corresponding to the thick wall portion is remarkably deteriorated, and the cell efficiency is lowered. Furthermore, the flow of the fuel gas is stabilized in the recess 14a, and the effect of disturbing the flow of the fuel gas is reduced. The effect of reducing the gas diffusion resistance, the effect of increasing the strength, and the effect of disturbing the flow of the fuel gas are lost.

  In the base tube 1, it is more preferable that each convex portion 12 a is continuous from one end to the other end. Thereby, intensity | strength can be maintained more effectively.

  In the figure on the right side of FIG. 2, the convex part 12a and the concave part 14a are provided periodically. However, it is not necessary to be provided periodically in this way. However, it is preferable that the convex portions 12a and the concave portions 14a are uniformly dispersed and no unevenness is present in order to prevent the stress from concentrating on a weak portion. As such an example, in the figure on the right side of FIG. 2, the line symmetric with respect to the line passing through the axis E and the point symmetric with respect to the axis E, the line symmetric with respect to the line passing through the axis E, Further, it is exemplified when the line is symmetrical with respect to a line shifted by 90 degrees from the line.

  For example, consider a base tube 1 having an inner diameter of about 33 mm and an outer diameter of about 36 mm. In the convex portion 12a, the base tube 1 has a thickness ta1 of 3 mm and a width A1 of 5 mm. In the recess 14a, the base tube 1 has a thickness tb1 of 1 mm and a width B1 of 8 mm. That is, the height H1 of the convex part 12a with respect to the concave part 14a is 2 mm. Eight convex portions 12a and eight concave portions 14a are provided.

  In FIG. 2, the cross-sectional shape of the convex part 12a and the recessed part 14a is a square-shaped groove | channel along a cylindrical surface. However, the present invention is not limited to this shape as long as the problems of the present invention can be solved. Other such examples are shown below. FIGS. 3A to 3C are cross-sectional views showing other modified examples of the configuration of the base tube 1 in the solid oxide fuel cell of the present invention. The cross section perpendicular | vertical to the axis | shaft E of the cylindrical surface of the outer wall 2a is shown.

  Referring to FIG. 3A, the inner wall 2b of the base tube 1 is provided with a convex portion 12b (thick portion) and a concave portion 14b (thin portion) in order along the circumferential direction of the cylindrical surface of the outer wall 2a. Are lined up. The convex portion 12b (thick portion) has a constant thickness in the circumferential direction. Since the recess 14b (thin wall portion) is a circular (round) groove, the thickness thereof is not constant in the circumferential direction. Although not shown, the convex portion 12b and the concave portion 14b extend in the direction of the axis E in parallel to the axis E, as in FIG.

  The thickness ta2 of the base tube 1 at the convex portion 12b, the width A2 of the convex portion 12b (width along the circumference of the cylindrical surface), the thickness tb2 of the base tube 1 at the concave portion 14b, and the width B2 of the concave portion 14b (circumference of the cylindrical surface) ) And the height H2 of the convex portion 12b with respect to the concave portion 14b are set based on the efficiency required for the cell and the required strength. These relationships are also the same as those shown in FIG.

  By doing in this way, the effect similar to the case of FIG. 2 can be acquired. In addition, in the case of (a), the thin portion forms a gently curved surface (arc) and has no corners. Therefore, there is no portion where stress is concentrated, which is advantageous in terms of strength.

  Referring to FIG. 3B, the inner wall 2b of the base tube 1 has a convex portion 12c (thick portion) and a concave portion 14c (thin portion) in order along the circumferential direction of the cylindrical surface of the outer wall 2a. Are lined up. The convex portion 12c (thick portion) has a constant thickness in the circumferential direction. Since the concave portion 14c (thin wall portion) is a triangular groove, the thickness thereof is not constant in the circumferential direction. Although not shown, the convex portion 12c and the concave portion 14c extend in the direction of the axis E in parallel to the axis E, as in FIG.

  The thickness ta3 of the base tube 1 at the convex portion 12c, the width A3 of the convex portion 12c (width along the circumference of the cylindrical surface), the thickness tb3 of the base tube 1 at the concave portion 14c, and the width B3 of the concave portion 14c (circumference of the cylindrical surface) ) And the height H3 of the convex portion 12c with respect to the concave portion 14c is set based on the efficiency required for the cell and the required strength. These relationships are also the same as those shown in FIG.

  Thus, the shape of the groove of the recess 14 includes at least a part of a circle, an ellipse, and a polygon, and these can be used alone or in combination. By using such convex portions 12 and concave portions 14, the same effect as in the case of FIG. 2 can be obtained.

  Referring to FIG. 3C, the inner wall 2b of the base tube 1 is provided with a convex portion 12d (thick portion) and a concave portion 14d (thin portion) along the circumferential direction of the cylindrical surface of the outer wall 2a. Are lined up. Since the convex part 12d (thick part) has a triangular cross section, the thickness is not constant in the circumferential direction. The concave portion 14d (thin wall portion) has a constant thickness in the circumferential direction. Although not shown, the convex portion 12d and the concave portion 14d extend in the direction of the axis E in parallel to the axis E, as in FIG.

  The thickness ta4 of the base tube 1 at the convex portion 12d, the width A4 of the convex portion 12d (width along the circumference of the cylindrical surface), the thickness tb4 of the base tube 1 at the concave portion 14d, and the width B4 of the concave portion 14d (circumference of the cylindrical surface) And the height H4 of the convex portion 12d with respect to the concave portion 14d is set based on the efficiency required for the cell and the required strength. These relationships are also the same as those shown in FIG.

  By doing in this way, the effect similar to the case of FIG. 2 can be acquired.

  Next, a first embodiment of the method for producing a solid oxide fuel cell of the present invention will be described.

  FIG. 4 shows an extrusion molding apparatus used in the method for producing a solid oxide fuel cell of the present invention. The extrusion molding apparatus 40 includes a control unit 41, a supply unit 42, an extrusion unit 45, a rectifying unit 46, a molding unit A47, a molding unit B48, and a core 49.

  The supply unit 42 is controlled by the control unit 41 at a supply amount for supplying the base tube material (slurry) to the extrusion unit 45 via a pipe 44 connecting the supply unit 42 and the extrusion unit 45. The extruding unit 45 extrudes the base tube material supplied from the supplying unit 42 to the rectifying unit 46 by an unillustrated extruding jig. The inside of the extruding part 45 is cylindrical. The rectifying unit 46 adjusts the flow of the base tube material extruded from the extruding unit 45. The forming part A47 (example: die) and the forming part B48 (example: die) form the base tube material extruded from the rectifying part 46 into a cylinder having an outer wall of a desired shape. At that time, the core 49 is formed so that the base tube material extruded from the rectifying unit 46 is formed into a cylinder having desired convex portions and inner walls of the concave portions. It includes a rotatable core 49-1 having a convex portion and a concave portion on the surface, and a core 49-2 having no convex portion and a concave portion on the surface. The control unit 41 controls the supply amount of the base tube material from the supply unit 42, the extrusion pressure in the extrusion unit 45, and the rotation of the core 49-1 (however, in the first embodiment, it is not rotated).

  FIG. 5 is a front view and a side view showing an example of the configuration of the core 49-1. The core 49-1a as an example of the core 49-1 has the same outer diameter R1 as the core 49-2 on the side of the core 49-2. And the inclined recessed part 52a and convex part 54a which go to the opposite side from the side are formed on the surface. The outer diameter of the convex portion 54a is R2 (> R1). The convex portion 12a of the base tube 1 is formed by the concave portion 52a. The concave portion 14a of the base tube 1 is formed by the convex portion 54a.

FIG. 6 is a flowchart showing a first embodiment of a method for producing a solid oxide fuel cell of the present invention. First, the base tube material is introduced into the supply unit 42 of the extrusion apparatus 40, and the base tube material is supplied to the extrusion unit 45. The extruding unit 45 extrudes the base tube material to the rectifying unit 46. The base tube material is pushed out to the forming portion 47 while being rectified by the rectifying portion 46. The base tube material has an outer shape inside the molding portion 47 and an inner shape outside the core 49-2. Further, the base tube material is formed into a cylindrical shape having desired irregularities, with the outer shape inside the forming portion 48 and the inner shape outside the core 49-1a. Thereby, a cylindrical cylindrical tube having an inner wall forming an uneven surface and an outer wall forming a cylindrical surface is extruded.
At this time, the core 49-1a continuously molds the cylindrical inner wall of the base tube material during extrusion molding. Thereby, the recessed part formed in the inner wall of the cylinder is formed as a groove continuously extending in the axial direction of the cylinder (= the axial direction of the columnar surface as the outer surface of the cylinder).
Thereafter, the cylindrical tube is dried (step S11). The control unit 41 controls the supply amount of the supply unit 42 and the extrusion pressure of the extrusion unit 45.

  After drying the cylindrical tube, the fuel electrode material is applied to a predetermined place on the outer surface of the cylindrical tube by a screen printing method and dried. Subsequently, an electrolyte material is applied and dried. The interconnector material is then printed and dried. The interconnector material is printed so that it is in at least partial contact with one anode material. Thereafter, they are dried (step S12).

  The base tube material, the fuel electrode material, the electrolyte material, and the interconnector material laminated on the outer surface thereof are sintered at a predetermined temperature at a time (step S13). Thereby, the base tube 1, the fuel electrode 3, the electrolyte membrane 4, and the interconnector 7 are completed. Next, an air electrode material is printed so as to cover the outer surface of the electrolyte membrane 4 and a part of the interconnector 7, and is dried (step S14). Thereafter, the air electrode material is sintered at a predetermined temperature (step S15). Thereby, the solid oxide fuel cell 10 shown in FIG. 1 is completed. At this time, the base tube 1 has the structure shown in FIG.

  Here, first, the fuel electrode material, the electrolyte material, and the interconnector material are respectively applied, dried, and fired on the cylindrical tube, and then the air electrode material is applied, dried, and fired. However, firing is not limited to the above case. The timing and number of firings are appropriately changed according to the design of the solid oxide fuel cell to be manufactured.

  The solid oxide fuel cell 10 manufactured by the above-described method generates power by the following operation. Under an operating temperature of 900 to 1000 ° C., a mixed gas of hydrocarbon and water vapor is introduced into the inside of the base tube 1. The mixed gas moves in the base tube 1 while the flow is disturbed by the convex portions 12 a and the concave portions 14 a of the base tube 1. Then, it diffuses through the thin pores of the porous base tube 1 and reaches the fuel electrode 3. As for the thick part, the fuel electrode 3 reaches the fuel electrode 3 by diffusing the pores of the thick part and the thin part. The mixed gas is steam reformed by the active metal nickel contained in the fuel electrode 3 to become a fuel gas in which hydrogen, carbon monoxide, and steam are mixed. The fuel gas passes through the pores of the fuel electrode 3 and reaches the electrolyte 4.

  On the other hand, air flows outside the base tube 1. The oxygen in the air reaches the electrolyte 4 through the pores of the air electrode 5 that is porous. Oxygen is ionized in the air electrode 5, passes through the electrolyte 4, and reaches the fuel electrode 3. A potential difference is generated between the fuel electrode 3 and the air electrode 5 due to an electrochemical reaction between oxygen and the fuel gas that has reached the fuel electrode 3, and electricity is generated by taking this out.

  Since the solid oxide fuel cell 10 using the base tube 1 shown in FIG. 2 manufactured by the above-described method has a recess 14a (thin wall portion), the fuel gas in the base tube 1 is directed to the fuel electrode. Gas diffusion resistance when diffusing can be reduced. Thereby, cell efficiency can be improved. Since it has the convex part 12a (thick part), strength reduction due to the thin part can be suppressed, and the strength of the base tube 1 can be kept within a predetermined range. By providing the convex portion 12a and the concave portion 14a, it is possible to further disturb the flow of the fuel gas and stir the region having a high water vapor concentration near the surface of the inner wall 2b with the fuel gas. Therefore, water vapor near the surface can be efficiently removed, and the water vapor concentration can be reduced. Thereby, the efficiency of a cell can be improved.

  The improvement in cell efficiency by providing a thin portion can be estimated as follows, for example, as a result of comparison with a conventional base tube having no uneven surface. For example, when the thickness of a conventional base tube without an uneven surface is 3 mm, if 50% of the inner wall of the base tube is formed as a recess 14a in FIG. 2, the cell output is 1.5 when tb1 = 1 mm. Improve twice.

(Second Embodiment)
Next, a second embodiment of the solid oxide fuel cell of the present invention will be described.

  FIG. 1 is a cross-sectional view showing a configuration of a second embodiment of a solid oxide fuel cell 10 of the present invention. Since it is the same as that of 1st Embodiment, the description is abbreviate | omitted.

  Next, the base tube 1a in the second embodiment of the solid oxide fuel cell of the present invention will be further described. FIG. 7 is a cross-sectional view showing the configuration of the base tube 1a in the second embodiment of the solid oxide fuel cell of the present invention. The left side shows a cross section perpendicular to the axis Ea of the cylindrical surface of the outer wall 2a, and the right side shows a cross section including the axis Ea and parallel to the axis Ea.

  Referring to the figure on the right side, a convex portion 22a (thick portion) and a concave portion 24a (thin portion) are arranged in order on the inner wall 2b of the base tube 1a along the circumferential direction of the cylindrical surface of the outer wall 2a. Yes. Each has a constant thickness in the circumferential direction. With reference to the left figure, the convex portion 22a and the concave portion 24a are provided in a spiral shape extending in the direction with respect to the axis Ea and turning along the inner wall 2b about the axis Ea. The arrow indicates the direction in which the groove (recess 24a) runs. The cross-sectional shape of the recess 24a is a square groove along the cylindrical surface.

  The thickness ta5 of the base tube 1a at the convex portion 22a, the width A5 of the convex portion 22a (width along the circumference of the cylindrical surface), the thickness tb5 of the base tube 1a at the concave portion 24a, and the width B5 of the concave portion 24a (circumference of the cylindrical surface) And the height H5 of the convex portion 22a with respect to the concave portion 24a is set based on the efficiency required for the cell and the required strength. These relationships are the same as those shown in FIG.

  The period (pitch) in the direction of the spiral axis Ea is set such that the flow rate of the fuel gas is disturbed based on the flow velocity or height H5 of the fuel gas flowing in the base tube 1 to a desired size. It is determined.

  By doing in this way, the effect similar to the case of FIG. 2 can be acquired. In addition, since the convex portion 22a (the concave portion 24a) has a spiral shape, the strength can be further increased as compared with the case of a straight line (FIG. 2).

  In the base tube 1a, it is more preferable that each protrusion 22a is continuous from one end to the other end. Thereby, intensity | strength can be maintained more effectively.

  In FIG. 7, the cross-sectional shape of the convex part 22a and the recessed part 24a is a square groove | channel along a cylindrical surface. However, the present invention is not limited to this shape as long as the problems of the present invention can be solved. Such other examples are the cross-sectional shapes of FIGS. In this case, the convex portions 12b, 12c, and 12d correspond to the convex portions 22b, 22c, and 22d, and the concave portions 14b, 14c, and 14d correspond to the concave portions 24b, 24c, and 24d, respectively. Since these are the same as those in the first embodiment, description thereof will be omitted.

  A second embodiment of the method for producing a solid oxide fuel cell of the present invention will be described.

  FIG. 4 shows an extrusion molding apparatus used in the method for producing a solid oxide fuel cell of the present invention. Since this is the same as in the first embodiment, a description thereof will be omitted.

  FIG. 8 is a front view and a side view showing an example of the configuration of the core 49-1b. The core 49-1b as an example of the core 49-1 has a concave portion 52b and a convex portion 54b formed in a spiral shape on the surface thereof. The core 49-1b is rotatably attached to the shaft. The convex portion 22a of the base tube 1 is formed by the concave portion 52b. A concave portion 24a of the base tube 1 is formed by the convex portion 54b.

FIG. 6 is a flowchart showing a second embodiment of the method for producing a solid oxide fuel cell of the present invention. First, the base tube material is introduced into the supply unit 42 of the extrusion apparatus 40, and the base tube material is supplied to the extrusion unit 45. The extruding unit 45 extrudes the base tube material to the rectifying unit 46. The base tube material is pushed out to the forming portion 47 while being rectified by the rectifying portion 46. The base tube material has an outer shape formed by the forming portion 47 and an inner shape formed by the core 49-2. Furthermore, the substrate tube material, the outer shape by the molding section 48 into a shape having the desired cylindrical surface, the inner shape into a shape having a desired uneven by core 49-1b rotating (rotation about an axis E ₀₎ Each is molded. Thus, a cylindrical cylindrical tube having an inner wall forming an uneven surface having a spiral groove and an outer wall forming a cylindrical surface is extruded. Thereafter, the cylindrical tube is dried (step S11). The control unit 41 controls the supply amount of the supply unit 42, the extrusion pressure of the extrusion unit 45, and the rotation (example: speed) of the core 49-1b.

  Steps S12 to S15 are the same as those in the first embodiment, and a description thereof will be omitted.

  Since the power generation operation of the solid oxide fuel cell 10 manufactured by the above-described method is the same as that of the first embodiment, the description thereof is omitted.

  In the solid oxide fuel cell 10 using the base tube 1 shown in FIG. 7 manufactured by the above-described method, the same effects as those of the first embodiment can be obtained. In addition, since the convex portion 22a (the concave portion 24a) has a spiral shape, the strength can be further increased as compared with the case of a straight line (FIG. 2).

  In the above embodiment, the base tube material is formed into a shape having a spiral groove on the inner shape by the rotating core 49-1b. However, it is also possible to provide a corrugated groove by periodically reciprocating the core 49-1b in the rotational direction. Thereby, while maintaining the strength, the flow of the fuel gas can be more disturbed, and the effect of stirring the region having a high water vapor concentration near the surface of the inner wall 2b with the fuel gas can be further enhanced. Therefore, water vapor near the surface can be removed more efficiently, and the water vapor concentration can be further reduced. Thereby, the efficiency of a cell can be improved more.

(Third embodiment)
Next, a third embodiment of the solid oxide fuel cell of the present invention will be described.

  FIG. 1 is a cross-sectional view showing a configuration of a third embodiment of a solid oxide fuel cell 10 of the present invention. Since it is the same as that of 1st Embodiment, the description is abbreviate | omitted.

  Next, the base tube 1b in the third embodiment of the solid oxide fuel cell of the present invention will be further described. FIG. 9 is a cross-sectional view showing the configuration of the base tube 1b in the third embodiment of the solid oxide fuel cell of the present invention. The left side shows a cross section perpendicular to the axis Eb of the cylindrical surface of the outer wall 2a, and the right side shows a cross section including the axis Eb and parallel to the axis Eb.

  Referring to the drawing on the right side, a convex portion 32a (thick portion) and a concave portion 34a (thin portion) or a concave portion 36a (thin wall portion) are formed on the inner wall 2b of the base tube 1b along the circumferential direction of the cylindrical surface of the outer wall 2a. Part) are arranged in order. Each has a constant thickness in the circumferential direction. Referring to the drawing on the left side, the convex portion 32a, the concave portion 34a, and the concave portion 36a are provided in a spiral shape extending in the direction with respect to the axis Eb and turning along the inner wall 2b around the axis Eb. However, the rotation direction with respect to the spiral axis Eb formed by the recess 34a is opposite to the rotation direction with respect to the spiral axis Eb formed by the recess 36a. That is, it has a cross spiral shape. The solid line arrow indicates the direction in which the first spiral groove (recess 34a) runs, and the broken line arrow indicates the direction in which the second spiral groove (recess 36a) runs. The cross-sectional shape of the recess 34a and the recess 36a is a square groove along the cylindrical surface.

  The thickness ta6 of the base tube 1b at the convex portion 32a, the width A6 of the convex portion 32a (the width along the circumference of the cylindrical surface), the thickness tb6 of the base tube 1b at the concave portion 34a and the concave portion 36a, and the width B6 of the concave portion 34a and the concave portion 36a. (Width along the circumference of the cylindrical surface) and the height H6 of the convex portion 32a with respect to the concave portion 34a and the concave portion 36a are set based on the efficiency required for the cell and the required strength. These relationships are the same as those shown in FIG.

  By doing in this way, the effect similar to the case of FIG. 2 can be acquired. In addition, since the convex portion 32a (the concave portion 34a and the concave portion 36a) has spiral shapes opposite to each other, the flow of the fuel gas is more disturbed than in the case of a simple spiral shape (FIG. 7). The region having a high water vapor concentration near the surface of the inner wall 2b can be further stirred with the fuel gas. Therefore, it is possible to more efficiently remove water vapor near the surface and lower the water vapor concentration. Thereby, the efficiency of a cell can be improved more.

  In FIG. 9, the cross-sectional shape of the convex part 32a, the recessed part 34a, and the recessed part 36a is a square-shaped groove | channel along a cylindrical surface. However, the present invention is not limited to this shape as long as the problems of the present invention can be solved. Such other examples are the cross-sectional shapes of FIGS. In this case, the convex portions 12b, 12c, and 12d correspond to the convex portions 32b, 32c, and 32d, and the concave portions 14b, 14c, and 14d correspond to the concave portions 34b, 34c, 34d, 36b, 36c, and 36d, respectively. Since these are the same as those in the first embodiment, description thereof will be omitted.

  A third embodiment of the method for producing a solid oxide fuel cell of the present invention will be described.

  FIG. 4 shows an extrusion molding apparatus used in the method for producing a solid oxide fuel cell of the present invention. Since this is the same as in the first embodiment, a description thereof will be omitted.

  FIG. 10 is a front view and a side view showing an example of the configuration of the core 49-1c. A core 49-1c as an example of the core 49-1 includes two cores 49-1cA and a core 49-1cB. The core 49-1cA and the core 49-1cB are coupled coaxially and controlled to rotate in opposite directions. The core 49-1cA is the same as the core 49-1b. A concave portion 52b and a convex portion 54b are formed in a spiral shape on the surface. The concave portion 34a of the base tube 1 is formed by the convex portion 54b. The core 49-1cB is obtained by attaching the core 49-1b in the opposite direction, and a concave portion 52c and a convex portion 54c are formed in a spiral shape on the surface thereof. A concave portion 36a of the base tube 1 is formed by the convex portion 54c. And the convex part 32a of the base tube 1 is formed of the recessed part 52b and the recessed part 52c.

FIG. 6 is a flowchart showing a third embodiment of the method for producing a solid oxide fuel cell of the present invention. First, the base tube material is introduced into the supply unit 42, and the base tube material is supplied to the extrusion unit 45. The extruding unit 45 extrudes the base tube material to the rectifying unit 46. The base tube material is pushed out to the forming portion 47 while being rectified by the rectifying portion 46. The base tube material has an outer shape formed by the forming portion 47 and an inner shape formed by the core 49-2. Furthermore, the substrate tube material, the molding portion 48 is formed with external into a shape having the desired cylindrical surface, rotating the rotation (rotation about an axis E ₀₎ to core 49-1cA and in the opposite direction to the one direction is molded inner shape into a shape having a desired uneven by the core 49-1cB to (rotation about an axis E _0). Thereby, a cylindrical cylindrical tube having an inner wall forming an uneven surface having two spiral grooves opposite to each other and an outer wall forming a cylindrical surface is extruded. Thereafter, the cylindrical tube is dried (step S11). The control unit 41 controls the supply amount of the supply unit 42, the extrusion pressure of the extrusion unit 45, and the rotation (example: speed and direction) of the cores 49-1cA and 49-1cB.

  Steps S12 to S15 are the same as those in the first embodiment, and a description thereof will be omitted.

  Since the power generation operation of the solid oxide fuel cell 10 manufactured by the above-described method is the same as that of the first embodiment, the description thereof is omitted.

  In the solid oxide fuel cell 10 using the base tube 1 shown in FIG. 9 manufactured by the above-described method, the same effects as those of the first embodiment can be obtained. In addition, since the convex portion 32a (the concave portion 34a and the concave portion 36a) has spiral shapes opposite to each other, the flow of the fuel gas is more disturbed than in the case of the spiral shape in the same direction (FIG. 7). Thus, water vapor near the surface of the inner wall 2b can be more efficiently removed, and the water vapor concentration can be lowered. Thereby, the efficiency of a cell can be improved more.

  In the embodiment of FIG. 9, the convex portion is at the position 32a and the concave portion (groove) is at the positions 34a and 36a. However, conversely, the concave portion may be at the position 32a and the convex portion may be at the positions 34a and 36a. That is, the substantially rhombic convex portion 32a in FIG. 9 becomes a substantially rhombic concave portion. In that case, since each convex part (position of 34a and 36a) is continuing from one edge part of the base tube 1b to the other edge part, compared with the case of FIG. 9, intensity | strength is more effective. Can be maintained.

  In the manufacturing method, for example, in the core 49-1b in FIG. 8, the circumferential width of each convex portion 54b is changed from 0 to the diagonal length of the concave portion of the approximately rhombic shape (position 32a). It may be controlled so as to fluctuate automatically. At that time, the period of the adjacent convex part 54b is shifted by 1/2 period. Further, the core 49-1b is not rotated. By doing so, it is possible to form a shape in which the two convex portions are each spirally continuous from one end to the other end of the base tube 1b.

  In the present embodiment, the core 49-1cA and the core 49-1cB in FIG. 10 are controlled to rotate in opposite directions. However, the core 49-1cA and the core 49-1cB may be rotated in the same direction. However, the rotational speed is controlled to be different from each other. As a result, one concave portion formed of the core 49-1cA and the other concave portion formed of the core 49-1cB form spiral grooves having different periods (pitch) on the inner wall of the base tube. Will do. Also in this case, the same effect as in the case of FIG. 10 can be obtained.

  In each of the above-described embodiments, it is possible to cope with minor changes such as changes in the core used for extrusion molding in the production of the base tube. That is, it can be manufactured at low cost using an existing apparatus. In addition, since the base tube material is reduced by the amount of the groove, the material cost can be reduced.

  In each of the above embodiments, the base tube is used as a support. However, the present invention can be similarly applied to the case where the base tube is made of a fuel electrode material or the air electrode material.

FIG. 1 is a cross-sectional view showing the configuration of a first embodiment of a solid oxide fuel cell 10 of the present invention. FIG. 2 is a cross-sectional view showing the configuration of the base tube 1 in the first embodiment of the solid oxide fuel cell of the present invention. FIGS. 3A to 3C are cross-sectional views showing other modified examples of the configuration of the base tube 1 in the solid oxide fuel cell of the present invention. FIG. 4 shows an extrusion molding apparatus used in the method for producing a solid oxide fuel cell of the present invention. FIG. 5 is a front view and a side view showing an example of the configuration of the core 49-1. FIG. 6 is a flowchart showing a first embodiment of a method for producing a solid oxide fuel cell of the present invention. FIG. 7 is a cross-sectional view showing the configuration of the base tube 1a in the second embodiment of the solid oxide fuel cell of the present invention. FIG. 8 is a front view and a side view showing an example of the configuration of the core 49-1b. FIG. 9 is a cross-sectional view showing the configuration of the base tube 1b in the third embodiment of the solid oxide fuel cell of the present invention. FIG. 10 is a front view and a side view showing an example of the configuration of the core 49-1c.

Explanation of symbols

1, 1a, 1b Base tube 2a Outer wall 2b Inner wall 3 Fuel electrode 4 Electrolyte 5 Air electrode 6 Cell 7 Interconnector 10 Solid oxide fuel cell 12 (a, b, c, d), 22 (a, b, c, d), 32 (a, b, c, d) Convex parts 14 (a, b, c, d), 24 (a, b, c, d), 34 (a, b, c, d), 36 ( a, b, c, d) Concave part 40 Extrusion molding device 41 Control part 42 Supply part 45 Extrusion part 46 Rectification part 47 Molding part A
48 Molding part B
49, 49-1, 49-1a, 49-1b, 49-1c, 49-1cA, 49-1cB, 49-2 Core 52a, 52b, 52c Concave portion 54a, 54b, 54c Convex portion

Claims (15)

A cylindrical porous substrate tube having an inner wall forming an uneven surface and an outer wall forming a cylindrical surface;
A solid oxide fuel cell comprising: a cell provided on a surface of the outer wall. The solid oxide fuel cell according to claim 1, wherein
The recess of the inner wall includes a groove extending in the axial direction of the cylindrical surface. Solid oxide fuel cell. The solid oxide fuel cell according to claim 1, wherein
The recess of the inner wall includes a groove having a first spiral shape with respect to an axis of the cylindrical surface. Solid oxide fuel cell. The solid oxide fuel cell according to claim 3, wherein
The recess includes a groove having a second spiral shape different from the first spiral shape with respect to an axis of the cylindrical surface. Solid oxide fuel cell. The solid oxide fuel cell according to any one of claims 2 to 4, wherein
The cross section of the groove includes at least a part of a circle, an ellipse, and a polygon. Solid oxide fuel cell. The solid oxide fuel cell according to claim 1, wherein
The convex portion of the inner wall extends continuously in the axial direction of the cylindrical surface. Solid oxide fuel cell. The solid oxide fuel cell according to any one of claims 1 to 6,
The base tube is made of a ceramic solid oxide fuel cell. The solid oxide fuel cell according to any one of claims 1 to 7,
The base tube is a solid oxide fuel cell through which fuel gas passes. The solid oxide fuel cell according to any one of claims 1 to 7,
The solid oxide fuel cell, wherein a cross section of the base tube perpendicular to the axis of the cylindrical surface is line symmetric with respect to a line perpendicular to the axis and point symmetric with respect to the axis. (A) forming a cylindrical tube by extruding the base tube material so that the outer wall forms a cylindrical surface and the inner wall forms an uneven surface;
(B) A fuel electrode material is bonded to the outer surface of the cylindrical tube, an electrolyte material is bonded to the outer surface of the fuel electrode material, and an interconnector is provided between the adjacent bonded electrolyte material and the fuel electrode material. Joining the materials;
(C) A method for producing a solid oxide fuel cell, comprising: firing the base tube material, the fuel electrode material, the electrolyte material, and the interconnector material. In the manufacturing method of the solid oxide fuel cell according to claim 10,
The step (b)
(B1) comprising a step of joining an air electrode material to the outer surface of the electrolyte material;
The step (c) includes:
(C1) A method for producing a solid oxide fuel cell, comprising: firing the air electrode material in addition to the base tube material, the fuel electrode material, the electrolyte material, and the interconnector material. In the manufacturing method of the solid oxide fuel cell according to claim 10,
(D) joining an air electrode material to the outer surface of the baked electrolyte material;
(E) A method for producing a solid oxide fuel cell, further comprising the step of firing the air electrode. In the manufacturing method of the solid oxide fuel cell according to any one of claims 10 to 12,
The step (a) includes:
(A1) A solid oxide fuel cell comprising a step of extruding the base tube material so that the recess of the inner wall includes a groove extending in the axial direction of the cylindrical surface. In the manufacturing method of the solid oxide fuel cell according to any one of claims 10 to 12,
The step (a) includes:
(A2) A method of manufacturing a solid oxide fuel cell, comprising: extruding the base tube material so that the concave portion of the inner wall includes a groove having a first spiral shape with respect to the axis of the cylindrical surface. The method for producing a solid oxide fuel cell according to claim 14,
The step (a2) includes:
(A3) A step of extruding the base tube material so that the recess of the inner wall further includes a groove having a second spiral shape different from the first spiral shape with respect to the axis of the cylindrical surface. Manufacturing method of fuel cell.

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