JPH10172594A - Method and device for distributing introduced gas to solid electrolyte fuel cell of flat plate type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an introduced gas distributing method and device with a solid electrolyte fuel cell, wherein the configuration is such that the pressure loss of the gas in a gas introduction part leading from gas supply ports to gas flow grooves in each separator and/or in the gas flow grooves is made good greater than the pressure loss in each gas supply port and thereby the gas is distributed uniformly to all unit cells belonging to the stack. SOLUTION: A solid electrolyte fuel cell of flat plate type includes unit cells each formed by arranging an air electrode and fuel electrode on the two surfaces of a solid electrolyte layer, and is structured so that these unit cells and separators 1 are stacked alternately, gas supply ports 1a are arranged at the four corners. Gas flow grooves 1c are formed at the two surfaces of each separator, wherein a gas flow throttle part 8 and/or obstacle 9 are provided in at least either of the gas introduction part and gas leadout part of the separator, and if the case is applicable, the depth of each gas flow groove is made shallower than the other portions of the groove so that a pressure losing function is equipped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for distributing an introduced gas in a flat solid electrolyte fuel cell.

[0002]

2. Description of the Related Art Recently, fuel cells which directly convert chemical energy inherent in fuel into electric energy by using, for example, air and hydrogen as oxidizing gas and fuel gas, respectively, have attracted attention from the viewpoint of resource saving and environmental protection. Research and development of solid electrolyte fuel cells have been progressing because they have many advantages such as high power generation efficiency and effective use of waste heat.

In order to supply a fuel gas and an oxidizing gas to a solid electrolyte fuel cell, an external manifold is provided on the outer periphery of the solid electrolyte fuel cell, and a gas supply / exhaust hole for each gas is provided in a separator and a solid electrolyte layer. There is an internal manifold type in which each gas is supplied and exhausted from each hole to each electrode surface of each unit cell through this hole.

FIG. 1 is a cross-sectional view of a flat solid electrolyte fuel cell of an internal manifold type, and FIG. 3 is a perspective view of a conventional separator.

[0005] A flat solid electrolyte fuel cell of the internal manifold type shown in FIG. 1 has (La, Sr) MnO _{3 on} both surfaces of a flat solid electrolyte layer 4 made of zirconia sintered body (YSZ) doped with yttria or the like. Air pole 6
And a flat cell 3 in which a Ni / YSZ cermet fuel electrode 5 is disposed, and adjacent cell 3 are electrically connected in series, and each cell 3 is provided with fuel gas and oxidant gas. And the separators 1 that distribute the fuel and the fuel electrode 5
A metal mesh 7 is interposed between the separator 1 and the fuel gas flow path side, and a stack is formed by interposing a sealant or a spacer 2 between the solid electrolyte layer 4 of the unit cell 3 and the separator 1. An electromotive force is generated by bringing the fuel gas and the oxidizing gas into contact with the electrode surface of each unit cell 3, respectively. The separator 1 separates the fuel gas and the oxidizing gas supplied to the fuel electrode 5 and the air electrode 6, respectively, to prevent cross leakage thereof, and to connect the cells 3 electrically in series. And A typical separator 1 is made of a conductive oxide such as strontium-doped lanthanum chromite.

As shown in the figure, an oxidizing gas distribution structure (a groove or the like to be described later) is formed on the surface of the separator on the air electrode side, and the fuel electrode is formed on the surface of the separator on the fuel electrode side. A fuel gas distribution structure to the fifth side is formed. In addition, gas supply holes 1a and exhaust holes 1a 'are respectively formed in the four corners of the separator, and furthermore, in order to evenly distribute the fuel gas and the oxidizing gas to the surfaces of the fuel electrode 5 and the air electrode 6, respectively, and A plurality of rows of gas flow grooves 1c and protrusions 1
b is engraved.

When the fuel cell is assembled, the protrusion 1b
Is in contact with the fuel electrode 5 or the air electrode 6 and is electrically conducted to form a current collector. The gas flow groove 1c communicates with a gas supply hole 1a formed at a diagonal corner through a triangular recess 1f formed on the surface of the separator 1. The gas flow grooves 1c and the triangular indents 1f form a distribution structure for the fuel gas and the oxidizing gas. Separator 1
1d is a sealing surface that overlaps with the solid electrolyte layer 4 and the spacer 2 of the unit cell 3.

[0008]

In a single-layer solid electrolyte fuel cell having a set of cells and a separator, there is no problem with the gas flow in the plane (front and back) of the separator. In a solid electrolyte fuel cell stacked in a layer (stack), if the pressure loss of the gas is small at the gas introduction portion where the gas flows from the gas supply hole 1a of the battery into the gas flow groove 1c of the separator, the separator of the separator may be damaged. The pressure loss in the gas supply hole 1a tends to affect the gas flow, so that the gas flow into the cell located upstream in the gas flow tends to increase, and the gas flowing into the cell located downstream is conversely increased. The inflow will decrease.

[0009] As a result, the fuel cell and the oxidizing gas are diluted in the unit cell, and the cell performance of the entire stack is lowered.

The present invention has been made in view of the above points, and in a flat solid electrolyte fuel cell of an internal manifold type, compared with the pressure loss in the air supply hole 1a, the gas flow groove of the separator from the air supply hole 1a. The gas pressure loss in the gas inlet to the gas inlet 1c is increased so that the pressure loss in the air supply hole 1a can be neglected. It is an object of the present invention to provide a method and an apparatus for distributing an introduced gas which distributes a gas to a gas.

[0011]

In order to achieve the above-mentioned object, the present invention provides a flat cell having an air electrode and a fuel electrode disposed on both sides of a flat solid electrolyte layer, and a cell having adjacent cells. Electrically connected in series and alternately stacking separators for distributing fuel gas and oxidizing gas to each unit cell, and providing gas supply / exhaust holes at the four corners of the separator and solid electrolyte layer, And in the flat plate solid electrolyte fuel cell of the internal manifold system in which the respective gas flow grooves are engraved on both surfaces of the separator, the gas introduction portion from the gas supply hole to the gas flow groove of the separator, from the gas flow groove of the separator One or both of the gas flow restricting portion and the obstacle are formed in one or both of the gas outlet portions to the gas exhaust hole.

Further, according to the present invention, in the above-mentioned plate type solid electrolyte fuel cell, the depth of the gas flow groove at the gas flow groove entrance and / or the gas flow groove exit of the separator is adjusted to the depth of the other part of the groove. It is characterized in that it is shallower and has a pressure loss function.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a conventional flat solid electrolyte fuel cell with reference to FIGS.
And a flat cell 3 having a fuel electrode 5 disposed therein and a separator for electrically connecting adjacent cells 3 in series and distributing a fuel gas and an oxidizing gas to each cell 3. 1
Are alternately stacked, a metal mesh 7 is interposed between the fuel electrode 5 and the fuel gas flow path side of the separator 1, and a sealant or spacer 2 is respectively interposed between the solid electrolyte layer 4 of the unit cell 3 and the separator 1. They are stacked on a stack with interposition.

An oxidant gas distribution structure to the air electrode 6 is formed on the surface of the separator on the air electrode side, and a fuel gas distribution structure to the fuel electrode 5 is formed on the surface of the separator on the fuel electrode side. I have. In addition, gas supply holes 1a and exhaust holes 1a 'are formed at the four corners of the separator, and the electrodes 5 and 4 are provided on the surfaces of the fuel electrode 5 and the air electrode 6 to evenly distribute the fuel gas and the oxidizing gas, respectively. A plurality of rows of gas flow grooves 1c and protrusions 1b are engraved on six surfaces. When the fuel cell is assembled, the protrusion 1b contacts the fuel electrode 5 or the air electrode 6 and is electrically conducted to form a current collector. Gas flow groove 1
c communicates with a gas exhaust hole 1a 'formed at a diagonal corner through a triangular recess 1f formed on the surface of the separator 1. The gas flow groove 1c and the triangular dents 1f, 1f 'form a distribution structure for the fuel gas and the oxidizing gas.

FIG. 2 is a perspective view of the separator used in the present invention.

As shown in FIG. 2, the gas flows from the gas supply hole 1a of the separator 1 into the gas flow groove 1c via the triangular recess 1f. The portion of the triangular dent 1f near the gas supply hole 1a is referred to as a gas inlet, and the portion of the triangular dent 1f 'near the gas exhaust hole 1a' is referred to as a gas outlet. For restricting), one or both of the throttle unit 8 and the obstacle 9 are provided. The throttle portion 8 and the obstacle 9 have an effect of increasing the pressure loss of the gas flowing into the gas introduction portion from the gas supply hole 1a. The flow direction of the gas in the gas introduction section is indicated by an arrow F. By increasing the pressure loss of the gas in the gas inlet so that the pressure loss in the gas supply hole 1a can be ignored, the gas flowing to the separator 1 located downstream in the gas flow, and thus to the cell 3 can be reduced. The flow rate does not decrease. In this way, gas can be evenly distributed to any of the unit cells 3 in the stack, and all unit cells 3 can have the same battery performance.

The inlet of the gas flow groove 1c is called a gas flow groove inlet 1e, and the outlet of the gas flow groove 1c is called a gas flow groove outlet 1o (indicated by chain lines in FIG. 2). At the gas flow groove inlet 1e and / or the gas flow groove outlet 1o, the depth of the gas flow groove 1c is made shallower than the other part of the groove, for example, the center, so that the gas flow has a pressure loss function. You can also.

The means for reducing the groove depth at the gas flow groove inlet 1e and / or the gas flow groove outlet 1o to be smaller than the depth of the other part of the groove as described above is provided by the above-described restricting portion 8 or obstacle. A pressure loss function can be provided by combining with one or both of the objects 9.

[0019]

EXAMPLE Each of plastic manifolds having the shapes shown in FIGS. 3 and 2 was stacked in 50 stages, and a black adhesive was inserted into a gas flow passage between the manifolds and sandwiched. Here, the former is A, and the latter is B. Air mixed with white fine powder (average particle size: 0.1 μm) was supplied at 1 l / min. , 5 l / min. , 10 l / mi
n. , 50 l / min. Each was introduced for 5 minutes.

The fine white powder mixed with the air is carried to each manifold, and is captured by the black adhesive in the gas flow passage, so that the flow of the air can be visualized.

In the case of A, no matter how much gas was introduced, many particles were trapped in the adhesive material of the upstream manifold, and almost no particles were trapped in the downstream material. That is, the gas easily flows to the upstream side.

On the other hand, in the case of B, it was found that particles were uniformly attached to both the upstream and downstream manifolds regardless of the flow rate of gas introduced, and that the gas flowed evenly.

Here, 5 l / min. Was flowed for 5 minutes, and the results shown in Table 1 were obtained when the weight of the particles introduced into the most upstream manifold and adhered to the adhesive was 1.000.

[0024]

[Table 1] Manifold shape Most upstream (first stage) Middle (25th stage) Most downstream (50th stage) A 1.000 0.002 0.001 B 1.000 1.001 0.999

[0025]

As described above, according to the present invention, a flat cell having an air electrode and a fuel electrode disposed on both surfaces of a flat solid electrolyte layer and an adjacent cell are electrically connected to each other. In the flat plate solid electrolyte fuel cell of the internal manifold type, which is connected in series and alternately laminated separators for distributing the fuel gas and the oxidizing gas to each unit cell, the gas flow groove extends from the gas supply hole of the separator. The gas flow in the gas inlet to the gas inlet of the separator is made larger than the pressure loss in the gas inlet. Pressure loss in the pores can be neglected, gas flow does not decrease even in downstream cells, gas is evenly distributed to all cells in the stack, and the performance of each cell is improved equally. With There is an effect that it is possible to improve the charge cell overall performance.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a flat solid electrolyte fuel cell of an internal manifold type.

FIG. 2 is a perspective view of a separator used in the present invention.

FIG. 3 is a perspective view of a conventional separator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Separator 1a Gas supply hole 1a 'Gas exhaust hole 1b Projection 1c Gas flow groove 1d Peripheral edge 1e Gas flow groove entrance 1f Triangular dent 1f' Triangle dent 1o Gas flow groove exit 2 Spacer 3 Flat plate cell 5 Fuel electrode 6 Air electrode 7 Metal mesh or metal felt 8 Restricted part 9 Obstacle F Flow direction of gas

Claims (8)

[Claims] 1. A flat cell in which an air electrode and a fuel electrode are disposed on both sides of a flat solid electrolyte layer, and adjacent cells are electrically connected in series, and a fuel cell is connected to each cell. Gas and oxidizing gas-distributing separators are alternately laminated, gas supply / exhaust holes are provided at the four corners of the separator and the solid electrolyte layer, and respective gas flow grooves are cut on both surfaces of the separator. In the flat solid electrolyte fuel cell of the internal manifold system provided, a gas introduction portion from the gas supply hole of the separator to the gas flow groove,
A gas distribution method for a flat solid electrolyte fuel cell, characterized in that a gas flow is restricted in one or both of a gas outlet from a gas flow groove of a separator to a gas exhaust hole. 2. A flat cell in which an air electrode and a fuel electrode are respectively disposed on both surfaces of a flat solid electrolyte layer, an adjacent cell being electrically connected in series, and a fuel cell connected to each cell. Gas and oxidizing gas-distributing separators are alternately laminated, gas supply / exhaust holes are provided at the four corners of the separator and the solid electrolyte layer, and respective gas flow grooves are cut on both surfaces of the separator. In the flat solid electrolyte fuel cell of the internal manifold system provided, a pressure loss of a gas flow is generated at one or both of a gas flow groove inlet and a gas flow groove outlet of the separator. A method for distributing an introduced gas in a solid oxide fuel cell. 3. A flat cell in which an air electrode and a fuel electrode are disposed on both surfaces of a flat solid electrolyte layer, and adjacent cells are electrically connected in series, and a fuel cell is connected to each cell. Gas and oxidizing gas-distributing separators are alternately laminated, gas supply / exhaust holes are provided at the four corners of the separator and the solid electrolyte layer, and respective gas flow grooves are cut on both surfaces of the separator. In the flat solid electrolyte fuel cell of the internal manifold system provided, a gas introduction portion from the gas supply hole of the separator to the gas flow groove,
A gas distribution device for a flat panel solid electrolyte fuel cell, wherein a gas flow restricting portion or an obstacle is formed in one or both of gas outlets from a gas circulation groove to a gas exhaust hole of a separator. 4. A flat cell in which an air electrode and a fuel electrode are disposed on both sides of a flat solid electrolyte layer, and adjacent cells are electrically connected in series, and each cell has a fuel cell. Gas and oxidizing gas-distributing separators are alternately laminated, gas supply / exhaust holes are provided at the four corners of the separator and the solid electrolyte layer, and respective gas flow grooves are cut on both surfaces of the separator. In the flat solid electrolyte fuel cell of the internal manifold system provided, a gas introduction portion from the gas supply hole of the separator to the gas flow groove,
An introduction gas distribution device for a flat solid electrolyte fuel cell, wherein a gas flow restricting portion and an obstacle are formed in one or both of a gas outlet portion and a gas outlet from a gas circulation groove of a separator to a gas exhaust hole. 5. A flat cell in which an air electrode and a fuel electrode are disposed on both surfaces of a flat solid electrolyte layer, and adjacent cells are electrically connected in series, and a fuel cell is connected to each cell. Gas and oxidizing gas-distributing separators are alternately laminated, gas supply / exhaust holes are provided at the four corners of the separator and the solid electrolyte layer, and respective gas flow grooves are cut on both surfaces of the separator. In the flat solid electrolyte fuel cell of the internal manifold type provided, the depth of the gas flow groove at the gas flow groove inlet portion of the separator is made shallower than the depth of the other portion of the groove to have a pressure loss function. Characteristic introduction gas distribution device for flat solid electrolyte fuel cells. 6. A flat cell in which an air electrode and a fuel electrode are disposed on both surfaces of a flat solid electrolyte layer, and adjacent cells are electrically connected in series, and a fuel cell is connected to each cell. Gas and oxidizing gas-distributing separators are alternately laminated, gas supply / exhaust holes are provided at the four corners of the separator and the solid electrolyte layer, and respective gas flow grooves are cut on both surfaces of the separator. In the flat solid electrolyte fuel cell of the internal manifold type provided, the depth of the gas flow groove at the outlet of the gas flow groove of the separator is made shallower than the depth of other portions of the groove to have a pressure loss function. Characteristic introduction gas distribution device for flat solid electrolyte fuel cells. 7. The pressure loss function according to claim 3, wherein the depth of the gas flow groove at the inlet of the gas flow groove of the separator is made shallower than the depth of the other portion of the groove.
Or the introduced gas distribution device for a flat panel solid electrolyte fuel cell according to 4. 8. The pressure loss function according to claim 3, wherein the depth of the gas flow groove at the outlet of the gas flow groove of the separator is made shallower than the depth of the other part of the groove.
Or the introduced gas distribution device for a flat panel solid electrolyte fuel cell according to 4.