JP3263561B2 - Solid electrolyte fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to solid oxide fuel cells .

[0002]

2. Description of the Related Art FIG. 3 shows a conventional solid oxide fuel cell . The fuel supply pipe 31 having the flange portion 31a is an upper tube sheet.
A fuel supply pipe fixing nut 34 is fixed to a counterbore part 32 a provided on the fuel cell 32 via a ring-shaped insulating material 33. The upper portion of the fuel supply pipe 31 is open to a space A, and this space is connected to a fuel supply pipe (not shown). The lower portion of the fuel supply pipe 31 is open at the tip of a solid electrolyte cell base tube 36 fixed to the lower tube plate 35.

The space above the upper tube sheet 32 is filled with a gas containing hydrogen, which is a fuel, and flows while flowing from the bottom to the inside of the cell base tube 36 as shown by the arrow. It reacts with the oxygen that has passed through the cell base tube 36, and becomes an exhaust gas containing water vapor as a result, flowing out into the space a between the upper tube sheet 32 and the lower tube sheet 35. The space c below the lower tube sheet 35 is filled with air.

[0004] The entire apparatus is placed in a state maintained at a temperature of about 1000 ° C. Under this high temperature environment, oxygen diffuses in the solid electrolyte and reacts with fuel hydrogen to form steam. At that time, a potential difference is generated above and below the solid electrolyte portion, and power generation is performed.

[0005] The seal portion is composed of the upper tube sheet 32 and the lower tube sheet.
The lower tube sheet portion is located in two places, and the lower tube sheet portion is considered to be insulated from the lower tube sheet 35 because the flange 36a of the cell gas pipe 36 is made of an insulating ceramic. Need not be performed.

On the other hand, since the upper tube sheet portion seals between the upper tube sheet 32 made of metal and the fuel supply pipe 31, if the two are brought into direct contact, the fuel supply pipe 36 falls to the ground. . The upper tube sheet 32 is grounded.

Normally, there is no problem even if the fuel supply pipe 31 is dropped to the ground, but it is possible to prevent a danger in the event that the fuel supply pipe 31 comes into contact with the cell base tube 36 due to thermal deformation due to high temperature. Therefore, the fuel supply pipe 31 is insulated from the upper tube sheet 32.

That is, an insulating material 33 is placed between the flange 31a of the fuel supply pipe 31 and the counterbore 32a of the upper tube plate 32 and between the fuel supply pipe fixing nut 34, and the fuel supply pipe 31 A ring-shaped insulating spacer 38 is placed on the outer periphery of the flange 31a of the fuel supply pipe 31 in order to prevent the position of the fuel supply pipe 31 from shifting left and right and coming into contact with the upper tube sheet 32.

[0009]

However, the prior art has the following problems. (1) Since it is a structure to attach a large number of cells , a large number of counterbore machining and internal thread machining are performed. Therefore, the number of processing steps for a large tube sheet becomes enormous, the time occupying a large processing machine becomes long, and the risk of processing errors increases.

(2) Since the temperature of the screw portion rises to near 900 ° C., it may not be able to come off due to seizure, in which case it is difficult to regenerate the tube sheet. (3) Insufficient sealing of gas, resulting in high frequency of leaks. This is due to the following. i)
The portion that becomes the seal surface on the tube sheet side is the depth of the hole in the counterbore portion, and it is difficult to achieve processing accuracy. ii) Due to the poor parallelism of the threaded part on the tube sheet side, the pressing surface pressure of the sealing surface is not uniform over the entire circumference (especially, when the entire tube sheet is deformed to warp due to long-term use, (The sealing surface of the cell located at is inclined, and if it is reworked, it will be inclined with the center axis of the screw.)

(4) The insulation cannot be checked until the assembly is completed. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a fuel supply pipe seal capable of improving the sealing performance between a fuel gas and air of a solid electrolyte fuel cell, increasing productivity and maintenance, and providing a low cost and high quality product. The purpose is to provide a structure.

[0012]

According to the present invention, the threading of the tube sheet is stopped to provide a simple through hole. In addition, the sealing surface is provided not on the inside of the hole but on the surface to facilitate processing. Therefore, the following structure was adopted.

(1) A spacer was inserted between the tube sheet and the fuel supply pipe to insulate the spacer from the tube sheet. (2) The spacer is cylindrical with a flange on one side and has a threaded structure on the other side.The tube plate is sandwiched and fixed between this flange and the spacer fixing nut fitted to the screw. .

That is, the present invention provides an upper tube sheet having a through hole for mounting a spacer in the thickness direction, and
Having an upper tube sheet and a lower tube sheet spaced apart from each other,
Area where fuel is filled by the upper tube sheet and the lower tube sheet
And the exhaust gas area containing water vapor and the area filled with air
The bottom tube sheet is divided into
Water vapor whose cylindrical solid electrolyte cell base tube has an open side
The upper portion is disposed so as to be located in an exhaust gas region including
On the tube sheet, the upper end is located in the area where the fuel is filled as described above.
And the lower end is at the bottom of the solid electrolyte cell base tube.
Metal fuel supply pipe extended to be located
Between the upper tube sheet and the fuel supply pipe.
A flange-shaped flange that contacts one main surface of the upper tube sheet
And the cylindrical part on the opposite side of this flange
Projecting toward the other main surface of the upper tube sheet;
A cylindrical spacer with a threaded part
And the spacer is screwed into the threaded portion of the spacer.
A spacer fixing nut for fixing to the upper tube sheet is provided.
The spacer and the spacer fixing nut and the upper tube sheet
Characterized by the fact that an insulating material is arranged on the surface in contact with
It is a solid electrolyte fuel cell .

In the present invention, the insulating material may be a sintered body of a non-electrically conductive ceramic such as alumina, silica, zirconia, titania, mullite, cordierite, silicon nitride, or a sheet formed by forming it into a fibrous form. Or coated by thermal spraying.

[0016]

In the present invention, the spacer and the tubesheet are electrically insulated because of the layer of insulating material between the spacer and the tubesheet. Therefore, there is no need to insulate between the spacer and the fuel supply pipe. In addition, one surface of the flange portion of the spacer and the surface of the tube sheet are in close contact with each other via the insulating material, so that the gas flow above and below the tube sheet is blocked and the sealing is performed. Furthermore,
The spacer and the fuel supply pipe are in direct contact with and tightly contact with each other to form a seal.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. However, in the present embodiment, the lower part is different from the conventional one (FIG. 3).
Since the configuration on the tube sheet side is the same, only the upper tube sheet side is described in detail.
are doing. (Example 1) Reference is made to FIG. Reference numeral 1 in the drawing denotes a metal upper tube plate having a through hole 1a for mounting a spacer at a substantially central portion, and an annular projection 1b provided at a lower peripheral edge of the through hole 1a.
The upper tube sheet 1 includes a circumferential spacer 2 and a flange portion 2.
a through an alumina coating 3 applied to the surface thereof. The upper tube sheet 1 is in contact with the spacer 2 via the alumina film 4 applied to the surface thereof. The upper tube
The protruding portion 1b of the plate 1 is provided for facilitating the processing of the sealing surface, and the lower surface side of the upper tube sheet 1 may be entirely finished or may be seated shallowly. However, if the counterbore is deep as in the conventional example, the processing accuracy deteriorates, which is not desirable.

The opposite side of the spacer 2 from the flange portion 2a is cylindrical, and this cylindrical portion protrudes above the surface of the tube sheet 1. Further, the outer peripheral surface and the inner peripheral surface of the cylindrical portion are threaded, and the threaded portion 2b
Is fitted with a spacer fixing nut 5. By tightening the threaded portion 2b, the flange portion 2a of the spacer 2 and the protruding portion 1b of the tube sheet 1 are strongly pressed and adhered to each other, so that the gas flow is prevented. An alumina film 6 as an insulating material is also sandwiched between contact portions between the spacer fixing nut 5 and the upper surface of the tube sheet 1. The spacers 2 and the tube sheet 1 are electrically insulated by the alumina coatings 3, 4, and 6.

The alumina coatings 3, 4, and 6 are formed by spraying alumina, but are not limited thereto.
Any ceramic spray such as zirconia spray may be used.
Instead of coating the surface as a thermal spray coating, an insulating material such as a ceramic fiber sheet or the like may be sandwiched.

A counterbore 2c is provided inside the spacer 2, and a bottom surface of the counterbore 2c is in contact with a flange 7a of a metal fuel supply pipe 7. This brim 7a
Are held down by a fuel pipe fixing nut 8 to be fitted to an inner thread portion cut into the inner surface of the counterbore portion 2c of the spacer 2.

As described above, the first embodiment is provided between the fuel supply pipe 7 and the tube sheet 1 having the through hole 1a for mounting the spacer and the annular projection 1b at substantially the center. A spacer 2 having a flange portion 2a in contact with the back surface and having a threaded portion 2b and a counterbore portion 2c in a cylindrical portion protruding from the front side of the tube sheet 1, and a spacer fitted to the threaded portion 2b of the spacer 2 A fixing nut 5, an alumina film 3, 6 provided between the tube plate 1 and the flange portion 2a of the spacer 2 and the spacer fixing nut 5 in contact with each other, and between the inside of the spacer 2 and the fuel supply pipe 7. A fuel pipe fixing nut 8 is provided.

In the first embodiment, by appropriately selecting the depth of the counterbore portion 2c of the spacer 2, a new structure can be obtained without changing the positional relationship between the conventional tube sheet and the fuel supply pipe. . That is, it is possible to change to the structure of the present embodiment by making a through hole in a tube sheet damaged by seizure of a screw in a conventional example. Therefore, it can be used as a conventional repair.

The seal face is formed in the same shape as that of the conventional example with respect to the counterbore portion. However, in the conventional example, the seal face is directly processed on the tube sheet. Since it is processed, the productivity is high, and the accuracy such as the flatness of the bottom surface of the counterbore portion and the parallelism of the screw can be easily obtained.

Embodiment 2 Referring to FIG. However, the same members as those in FIG. Reference numeral 21 in the figure is a spacer . this
The spacer 21 has a flange portion 2a at a lower portion and a threaded portion at an upper portion similarly to the spacer of the first embodiment.
Unlike the first embodiment, the inner side surface has no threaded portion. The collar 7a of the fuel supply pipe 7 is provided at a position slightly higher than the surface of the tube sheet 1, and the collar 7a
Is in contact with the upper end surface of the spacer 21. Furthermore,
A threaded portion 21a of the spacer 21 has a fuel supply pipe fixing nut 22 that shares a thread surface with the spacer fixing nut 6.
Is tightened. At the time of this tightening, the lower surface of a part of the spacer fixing nut 22 is
It comes into contact with the upper surface of the flange portion 7a.

According to the second embodiment, since the sealing surface is an end surface, the accuracy is more easily obtained than in the first embodiment. In addition, when the fuel supply pipe is removed for inspection or the like, the inspection of the sealing surface can be performed. It is easy to repair wounds. Further, as compared with the first embodiment, the internal thread processing and boring of the spacer are not required, and the number of processing steps is further reduced as compared with the first embodiment.

[0026]

According to the present invention, as described in detail above, the following effects can be obtained. (1) The processing of the tube sheet, which is a large member, becomes a simple through hole, and since the sealing surface of the tube sheet is on the surface, the processing accuracy is increased, so that the sealing property is improved and the productivity is high.

(2) When the screw portion is seized, it can be easily repaired by destroying only the spacer portion. (3) Since parts requiring processing accuracy are gathered in a small spacer, it is easy to increase processing accuracy and sealability is improved. Further, the cost is reduced because the productivity is increased.

(4) It is possible to check the insulation between the tube sheet and the spacer when the spacer is fixed to the tube sheet. Therefore, when attaching the fuel supply pipe, it is not necessary to pay attention to insulation from the tube sheet, and efficient work can be performed.

By the above (1) to (4), the sealing performance between the fuel gas of the solid electrolyte fuel cell and the air is improved, the productivity and the maintainability are improved, and a low cost and high quality product is obtained.

[Brief description of the drawings]

FIG. 1 shows a solid electrolyte fuel cell according to a first embodiment of the present invention.
Sectional drawing of the principal part .

FIG. 2 shows a solid electrolyte fuel cell according to Embodiment 2 of the present invention.
Sectional drawing of the principal part .

FIG. 3 is a cross-sectional view of a conventional solid oxide fuel cell .

[Explanation of symbols]

1 ... (upper) tube sheet , 2, 21 ... spacer, 2
a: flange portion, 2b, 21a: threaded portion, 2c: counterbore portion, 3, 4, 6: alumina film, 5, 8: fixed nut, 7, 22: fuel supply pipe.

Claims (2)

(57) [Claims] 1. An upper tube sheet having a through hole for mounting a spacer in a thickness direction, and an upper tube sheet separated from the upper tube sheet below the upper tube sheet.
A lower tubesheet disposed between the upper tubesheet and the upper tubesheet.
And the area filled with fuel by the lower tubesheet and water vapor
It is divided into an exhaust gas area and an area filled with air, and the lower tube sheet has a bottomed cylindrical solid with one end opened.
The exhaust pipe containing water vapor whose opening side is the electrolyte cell base pipe is described above.
And the upper tube sheet is filled with the fuel described above at the upper end side.
Region and the lower end side of the solid electrolyte cell base tube.
Metal fuel supply pie extending to the bottom
Is disposed between the upper tube sheet and the fuel supply pipe.
Has a flange-shaped flange that contacts one main surface of the tubesheet
And the cylindrical part on the opposite side of the flange
Protruding from the other main surface side of the tube sheet, and this protruding portion
The cylindrical spacer that is the threaded part is placed
The spacer is threaded to the upper part of the spacer.
A spacer fixing nut for fixing to the tube sheet is provided, and the spacer and the spacer fixing nut are in contact with the upper tube sheet.
Solid material characterized by insulating material disposed on the surface to be
Electrolyte fuel cell . 2. The insulating material is a sintered body of ceramics having no electrical conductivity, such as alumina, silica, zirconia, titania, mullite, cordierite, silicon nitride, or the like, which is formed into a fibrous sheet and processed into a sheet. 2. The solid electrolyte fuel cell according to claim 1, wherein said solid electrolyte fuel cell is coated by thermal spraying.