JPH08241728A - Phosphoric acid resisting gas manifold for fuel cell - Google Patents

Abstract

PURPOSE: To prevent the corrosion of a gas manifold by the penetration of phosphoric acid to the gas manifold, and also prevent the short-circuit accident of a cell main body by a phosphoric acid liquid junction caused by the breakage of the coating of the gas manifold or the gas leak accident by the corrosion of the gas manifold. CONSTITUTION: When the inner surface of a gas manifold 20 is lined with a fluorine resin sheet highly resistant to phosphoric acid, for example, a PFA resin sheet 21, the PFA resin sheet 21 is molded according to the inner surface of the gas manifold. The corner part is heated and pressure-coated a patch 22 is heated and pressure-coated to the PFA resin sheet outer surface of the bottom corner part, and it is pulled out by a slit 23 provided also so as to degas the corner part of the gas manifold 20, and fixed by use of a stopper 24. The outer circumferential side part of the PFA resin sheet 21 is turned round on the turned reverse side of the gas manifold 20, and a round bar 31 is fitted and fixed so as to press the PFA resin sheet 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphoric acid resistant manifold used in a fuel cell stack.

[0002]

2. Description of the Related Art In a fuel cell, hydrogen obtained by reforming natural gas, methane gas and the like and air as an oxidant are supplied into a main body of the fuel cell and electrochemically supplied through an electrolyte such as phosphoric acid solution. It is a structure in which one unit cell having a power generation function as described above is laminated to form a laminated body structure (cell stack structure).

FIG. 16 is an exploded perspective view of a cell stack structure of a conventional fuel cell. The unit cell 1 of the fuel cell body is
A fuel electrode 3 to which hydrogen is supplied in the direction of arrow A is arranged on one surface side of the matrix layer 2 holding the electrolyte, and an air electrode 4 to which air is supplied in the direction of arrow B is arranged on the other surface side. The fuel electrode 3 and the air electrode 4 are formed by laminating the grooved electrode base materials 5 and 6, respectively, and laminating the separator 7 on either one of the grooved electrode base materials 5 and 6. Each time a large number of the unit cells 1 are stacked, the cooling plates 8 are stacked to form a single sub-stack 9, and a large number of the sub-stacks 9 are stacked to form a cell stack 10.

At the top and bottom of the cell stack 10,
A tightening plate 11 is attached to each, and the cell stack 10 and the upper and lower tightening plates 11 are tightened by a tie rod 12 to be integrated as a battery stack 13.

As shown in FIG. 17, a pair of hydrogen gas manifolds 15a, 15b for hydrogen and a pair of hydrogen gas manifolds 15a, 15b for allowing hydrogen gas and air gas to flow in directions perpendicular to each other are formed on the four side surfaces of the battery stack 13. A pair of air gas manifolds 16a and 16b are attached.

Battery stack 13 and gas manifold 15
Gaskets 18 are provided on the contact surfaces with a, 15b, 16a, 16b in order to prevent problems such as a decrease in output and efficiency due to leakage of air or hydrogen gas.

By the way, the gas manifolds 15a, 16
When hydrogen and air are respectively supplied to a and the reaction proceeds, the phosphoric acid impregnated into the electrolyte layer 2 and the grooved electrode materials 5 and 6 of the unit cell 1 forming the cell stack diffuses into hydrogen and air, The steam is carried into the gas manifolds 15b and 16b.

If the hydrogen and air containing phosphoric acid come into direct contact with the inner surfaces of the metal gas manifolds 15b and 16b, they will be severely corroded in the high temperature state and holes will be immediately formed. Therefore, as a treatment for protecting the gas manifolds 15b and 16b from corrosive phosphoric acid, a fluorine resin coating as shown in US Pat. No. 4,950,563 is applied. However, there are problems such as permeation of phosphoric acid due to pinholes and the linear expansion coefficient of the resin coating being about 10 times that of the gas manifolds 15b and 16b, resulting in poor adhesion due to repeated thermal history and peeling of the coating. Therefore, it is not economical because it has to be applied thickly after expensive pretreatment and many coating steps.

[0009]

As described above, the gas manifolds 15b and 16b are coated with a fluorine resin as a phosphoric acid resistant treatment, but there is a problem such as pinholes and peeling due to poor adhesion. Has a problem that phosphoric acid permeates the base material due to its relatively thin coating and corrodes the base material, and it lacks reliability.

Therefore, the present invention eliminates the incompleteness of the film in the conventional coating method by lining the fluorine-based resin sheet having a strong phosphoric acid resistance, the phosphoric acid permeation resistance is sure, and the electrical insulation property is improved. It is also an object of the present invention to provide a phosphoric acid gas manifold having excellent corrosion resistance and sufficient corrosion resistance.

[0011]

Means for Solving the Problems In order to line a gas manifold with a fluororesin sheet having strong phosphoric acid resistance, for example, a PFA resin sheet, the PFA resin sheet is formed to fit the inner surface of the gas manifold, and the corner portion is heat-pressed.
The patch is heated and pressure-bonded to the outer surface of the sheet at the bottom corner,
By pulling it out from a slit provided also for degassing the corner portion of the gas manifold and fixing it with a stopper, a member different from the main body PFA resin sheet itself can be fixed externally. The outer peripheral part of the PFA can be easily fixed by one-touch by fitting a round bar having a cushioning property into the folded back side of the gas manifold so as to press the PFA resin sheet. And the PF around the gas manifold
The creepage distance between the gas manifold and the cell stack can be ensured by ensuring a sufficient folding length of the A resin sheet.

[0012]

By covering the entire inner surface of the gas manifold with the sheet-shaped phosphoric acid resistant material, the phosphoric acid corrosion of the metallic material can be completely prevented. Further, the peripheral edge portion also has a sufficient dimension as a creeping surface and is folded back, whereby a simple and complete phosphoric acid resistant structure can be obtained as a phosphoric acid treatment structure.

By covering the inner surface of the gas manifold with a lining of a fluorocarbon resin sheet, the gas that has permeated the resin sheet fills up with the gas manifold, and the sheet itself is pushed up by thermal expansion during start-up and stop. For P on the corner of the gas manifold
Degas through the fixing slit of the FA resin sheet.

By connecting the degassing pipe to the back surface of the gas manifold and connecting the pipe outlet to the suction side of the package ventilation fan, the PFA is released at the same time as degassing.
Fix the resin sheet.

[0015]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view of a gas manifold 20 attached to four side surfaces of a fuel cell stack according to the present invention, and FIG. 2 is a sectional view thereof. The PFA resin sheet 2 indicated by the dotted line is formed on the inner surface of the gas manifold 20.
1 is pasted inside. A slit 23 is provided in the corner portion of the bottom surface of the gas manifold, and the PFA resin sheet 21 is fixed at the corner portion. Fixed position pitch P1
, P2 is 30 depending on the stack height and width of the cell stack 10.
Adjusted from 0 to 500 mm.

FIG. 3 is a detailed sectional view of the corner portion of the "X" portion of FIG. 1, and FIG. 4 is a perspective view of the patch 22 mounting portion. The patch 22 is thermocompression bonded to the corner portion of the "X" portion under the condition that the PFA resin sheet 21 itself is not melted, and the slit 23 shown in FIG. 5 is formed in the gas manifold corner portion facing the patch 22. Patch 2 more
The PFA resin sheet 21 is fixed by pulling out 2 and inserting the stopper 24 to the outside. The slit 23 also has a function of removing the gas filled between the PFA resin sheet 21 and the gas manifold 20 by a permeating gas of air or hydrogen. The width h of the slit 23 is the patch 22
The width H is 5 to 10 mm larger to absorb the assembly error.

FIG. 6 is a sectional view of the slit 23 and the patch 23.
Toba mouth is chamfered to prevent scratches. FIG. 7 is a sectional view of the gas manifold gas supply / discharge flange portion. A cylindrical PFA resin sheet 26 is attached to the inner surface of the flange 25. Collars 26a and 26b are integrally formed on both ends of the resin sheet 26, the PFA resin sheet 21 and the collar 26a are thermocompression-bonded inside the gas manifold, and the packing 27 is sandwiched between the outer flange 25 and the flange 26b. Supply and exhaust pipe 28
Is attached.

FIG. 8 is a sectional view of the periphery of the gas manifold. PFA resin sheet 2 at the peripheral edge of the gas manifold
1 is folded back and sandwiched by U-shaped cross-section clamps 29 from above the peripheral end of the gas manifold, and the PFA resin sheet 21 and the peripheral part of the gas manifold are integrally fixed by rivets 30. As a modified example, as shown in FIG. 9, a round bar 31 made of an elastic material such as silicon rubber can be fitted and fixed with one touch.

FIG. 10 is a perspective view of a corner portion of the PFA resin sheet 21, in which the thermocompression bonding portion 32 shown by hatching is thermocompression bonded to gas tight. As a method of matching, a superposed portion 32a shown in FIG. 11 or a worship portion 32b shown in FIG.

As another embodiment, in FIG. 13, the PFA resin sheet 21 is fixed with a heat resistant adhesive 33. The adhesive 33 includes a corner portion on the bottom surface of the gas manifold and a folded portion 34 on the peripheral portion.
It is glued in. A gas vent hole 35 is formed in the back of the gas manifold for venting the permeated gas. FIG.
4 is a PFA resin sheet 36 integrally molded by an autoclave method, and the gas manifold 37 is a PFA resin sheet.
A draft angle α is provided so that the resin sheet can be easily removed from the mold.

FIG. 15 shows the degassing and PFA resin sheet 21.
It is a conceptual diagram that also serves as a fixation. Each gas manifold 20
A gas venting pipe 33 is connected to a gas venting hole formed in the back part of the PVA, and is connected to the suction side of a package ventilation fan 39 to make a negative pressure between the gas manifold 20 and the PFA resin sheet 21. Fix the resin sheet.

[0022]

As described above in detail, according to the present invention, the structure of the phosphoric acid lining member is simple and the assemblability is good.
PF that does not fill gas and obstructs gas flow
A The resin sheet fits well to the gas manifold without deformation, the thickness can be selected so that phosphoric acid does not penetrate, and the width dimension of the folded end of the gas manifold is secured, so the electrical insulation creepage distance is also increased. You can secure enough,
A phosphoric acid resistant gas manifold having good phosphoric acid resistant performance and high reliability can be provided.

[Brief description of drawings]

FIG. 1 is a plan view showing a phosphoric acid resistant gas manifold according to the present invention.

FIG. 2 is a sectional view of the phosphoric acid resistant gas manifold shown in FIG.

FIG. 3 is a detailed view of a corner portion of the phosphoric acid resistant gas manifold of the present invention.

FIG. 4 is a perspective view showing a PFA resin sheet patch portion of the present invention.

FIG. 5 is a perspective view showing a slit portion of the phosphoric acid resistant gas manifold corner of the present invention.

FIG. 6 is a sectional view showing the slit portion of the phosphoric acid resistant gas manifold of the present invention.

FIG. 7 is a cross-sectional view showing a phosphoric acid resistant manifold flange portion of the present invention.

FIG. 8 is a sectional view showing the peripheral portion of the phosphoric acid resistant gas manifold of the present invention.

FIG. 9 is a cross-sectional view showing another example of fixing the end portion of the PFA resin sheet of the present invention.

FIG. 10 is a perspective view showing a corner PFA resin sheet thermocompression bonding portion of the present invention.

FIG. 11 is a perspective view showing a method of joining the corner portion PFA resin sheet thermocompression bonding portion of the present invention.

FIG. 12 is a perspective view showing a method for joining the corner portion PFA resin sheet thermocompression bonding portion of the present invention.

FIG. 13 is a perspective view of a PFA resin sheet assembly according to another embodiment of the present invention.

FIG. 14 is a PFA resin sheet molding diagram of another embodiment of the present invention.

FIG. 15 is a conceptual diagram showing gas release and PFA resin sheet fixing according to another embodiment of the present invention.

FIG. 16 is a configuration diagram showing a conventional cell stack.

FIG. 17 is a perspective view showing an entire conventional cell stack.

[Explanation of symbols]

 1 Single Battery 10 Cell Stack 13 Battery Stack 20 Gas Manifold 21 PFA Resin Sheet 22 Patch 23 Slit 24 Stopper 26,36 PFA Resin Sheet 31 Round Bar 33 Heat Resistant Crimping Material Section 38 Gas Vent Piping

Claims (9)

[Claims] 1. In a gas manifold for supplying and exhausting a reaction gas, which is attached to four side surfaces of a fuel cell stack, in order to line a phosphoric acid resistant resin sheet on the inner surface of the gas manifold, the gas manifold inner surface is previously aligned with the inner surface of the gas manifold. A phosphoric acid resistant gas manifold for a fuel cell, characterized in that the sheet formed by bending each corner portion and thermocompression bonding the joint portion is lined on the inner surface of the gas manifold. 2. A patch is thermocompression-bonded to the outer surface of the bottom corner of the phosphoric acid-resistant resin sheet, the patch is pulled out from a slit of the corner of the gas manifold, and a stopper is externally inserted into the patch. 2. The phosphoric acid resistant gas manifold for a fuel cell according to claim 1, wherein the phosphoric acid resistant manifold is fixed. 3. The phosphoric acid resistant manifold for a fuel cell according to claim 1, wherein the gas passing through the phosphoric acid resistant resin sheet is degassed by the slit of the corner portion of the gas manifold. 4. The outer periphery of the phosphoric acid resistant resin sheet is wound around the folded back side of the peripheral portion of the gas manifold, and a round bar is fitted from above to fix the phosphoric acid resistant resin sheet. The phosphoric acid resistant gas manifold for a fuel cell according to claim 1. 5. The phosphoric acid resistant manifold for a fuel cell according to claim 1, wherein the phosphoric acid resistant resin sheet is made of a fluorine-based resin PFA or FEP material. 6. The PFA resin sheet has a thickness of 0.05.
To 0.5 mm, the phosphoric acid resistant gas manifold for a fuel cell according to claim 5. 7. The phosphoric acid resistant gas manifold for a fuel cell according to claim 5, wherein the PFA resin sheet is intermittently adhered to the inner bottom corner of the gas manifold with a heat resistant adhesive. 8. The PFA resin sheet is fixed by connecting a degassing pipe that has passed through the phosphoric acid resistant resin sheet to the suction side of a package ventilation fan. Phosphorus resistant gas manifold for fuel cells. 9. The phosphoric acid resistant gas manifold for a fuel cell according to claim 5, wherein the PFA resin sheet is formed into an inner surface shape of the gas manifold by an autoclave method.