JPH03280359A - Fuel cell with solid electrolyte - Google Patents

Abstract

PURPOSE:To prevent crack initiation and prolong the lifetime of a battery by lessening the oxygen and fuel concentration gradient between the upstream and downstream in the intra-cylindrical space of a fuel cell element with solid electrolyte, and making the gas penetration amount in the upstream smaller than downstream. CONSTITUTION:A plurality of circular holes 2 having the same diameter are arranged longitudinally at the side circumferential surface 1b of an oxidation gas supply pipe 1. Two rows of flat plate ribs 3 are arranged between the side circumferential surface 1b and a porous supporting pipe 4. Thereby oxidation gas supplied to the supply pipe 1 spouts out of the circular holes 2 one after another as shown by the arrow C, and after service for power generation, is mixed with the oxidation gas exhausted from an oxidation gas supply hole 1a situated at the foremost, to be exhausted to an exhaust gas chamber 19 as shown by the arrow D. The rate of open voids of this supporting pipe 4 is lessened of the upstream of the oxidation gas flow in the intra-cylindrical space 29, while is enlarged in the downstream to a specified extent. Thereby the amount of oxidation gas penetrating the supporting pipe 4 can be uniformized, so that heat emission from the whole is made uniform to prevent crack initiation.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to solid oxide fuel cells.

(Prior Art) Recently, fuel cells or power generation devices have been attracting attention. This is a device that can directly convert the chemical energy contained in fuel into electrical energy, and because it is not subject to the restrictions of the Carnot cycle, it has inherently high energy conversion efficiency and can be used for a variety of fuels (naphtha, natural gas, etc.). , methanol, coal reformed gas.

It is an extremely promising technology as it uses heavy oil (such as heavy oil), has low pollution, and its power generation efficiency is not affected by the size of the facility.

In particular, solid oxide fuel cells (5OFC)
Because it operates at a high temperature of °C, the electrode reaction is extremely active, there is no need for expensive precious metal catalysts such as platinum, the polarization is small, and the output voltage is relatively high, so the energy conversion efficiency is high compared to other fuel cells. Remarkably high. Furthermore, since all the structural materials are made of solid materials, they are stable and have a long life.

FIG. 9 is a schematic cross-sectional view showing an example of such a 5OFC.

In Fig. 9, 1 is an oxidizing gas supply pipe for introducing oxidizing gas such as air, 4 is a bottomed porous support tube, 5 is an air electrode, 6 is a solid electrolyte, 7 is a fuel electrode, and 8 is an oxidizing gas While holding the supply pipe l, the oxidizing gas chamber 18 and the exhaust gas chamber 19
The upper plate that separates the
9 is a bottom plate having a fuel inlet hole 10a that holds the battery reaction chamber 20 and the fuel chamber 30, and a gas outlet hole 9 that separates the exhaust gas chamber 19 and the battery reaction chamber 20.
This is a plate with a.

In this state, when an oxidizing gas such as air is supplied from the oxidizing gas chamber 18 to the oxidizing gas supply pipe 1 as shown by the arrow, the oxidizing gas discharged from the oxidizing gas supply port 1a flows through the bottomed portion as shown by the arrow B. The gas is reversed, flows inside the cylinder space 29, and flows out into the exhaust gas chamber 19 as shown by the arrow. Meanwhile, the bottom plate l
By flowing a fuel gas such as H2 or CH along the outer surface of the 5OFC element 40 through the O fuel inlet hole 10a, a flow of oxygen ions is generated through the solid electrolyte and reacts with the fuel at the fuel electrode, resulting in , an electric current flows between the air electrode and the fuel electrode, and it can be used as a battery. Since this fuel cell is used at high temperatures of around 1000'C,
It can be said that the form shown in FIG. 9, which can be constructed without a seal part, is a preferable form.

(Problem to be solved by the invention) In the practical application of SOFC, it is necessary to reduce costs and improve power density. Therefore, it is required to increase the power generation output per unit by increasing the length of the 5OFC element 40. However, if the bag tube-shaped 5OFC element 40 is lengthened,
There was a problem that the temperature gradient along the longitudinal direction of the 5OFC element 40 due to the non-uniformity of the electrode reaction became thick, increasing thermal strain stress, causing cracks to occur in the 5OFC element, and shortening its life.

That is, in the vicinity of the oxidizing gas supply port 1a, since the oxygen content is still high, the electrode reaction, which is an electrochemical reaction, is active, so the temperature rises, and this temperature rise causes the oxygen ions and fuel on the fuel electrode surface to increase. The electrode reaction with the gas becomes more active. On the other hand, at the other end, the concentration of oxidizing gas has decreased considerably, so the reaction is inactive and the temperature is low. The longer the battery, the thicker it becomes.

(Progress leading to the invention) For this reason, the inventor has devised a method of changing the open porosity in the longitudinal direction of the porous support tube 4 of the 5OFC element 40 to make the amount of oxygen permeation almost uniform in the longitudinal direction. However, as the length of the 5OFC element 40 becomes longer, the open porosity of the porous support tube 4 on the downstream side of the oxidizing gas must be increased, or as the porosity increases, the support The strength of the tube 4 is reduced. Therefore, there is a limit to the open porosity that can be achieved in the longitudinal direction of the porous support tube 4 described above.

Furthermore, the method of simply increasing the flow rate of oxidizing gas in the structure shown in FIG. 9 not only cools the 5OFC element and reduces thermal efficiency and power generation efficiency, but also tends to cause cracks to occur in the 5OFC element due to thermal strain.

A similar problem also occurs in a type 5OFC in which a fuel electrode is provided inside the solid electrolyte 6 and fuel gas is supplied into the cylinder space to generate electricity. Moreover, in this case, the fuel gas whose concentration has decreased contains a considerable amount of CO2 and water vapor, and these adhere to the electrode surface and inhibit the reaction, making the reaction even more inactive and causing a temperature drop. Uniform or marked.

The object of the present invention is to reduce reactivity and temperature non-uniformity in the longitudinal direction of the cell, reduce thermal distortion stress, extend the life of the cell, and improve power generation efficiency in a bottomed cylindrical solid oxide fuel cell. The object of the present invention is to provide a solid oxide fuel cell that can achieve this goal.

(Means for Solving the Problems) The present invention provides a solid electrolyte fuel cell element in which an air electrode, a solid electrolyte, and a fuel electrode are formed on the outer peripheral surface of a bottomed cylindrical porous support, and A solid oxide fuel cell having a gas supply pipe inserted into a cylinder space of a type fuel cell element, wherein a gas supply section that supplies oxidizing gas or fuel gas to the cylinder space is connected to the gas supply pipe. The amount of gas permeation through a portion of the bottomed cylindrical porous support that is provided on at least a side circumferential surface of the bottomed cylindrical porous support and faces toward the upstream side of the gas flow flowing through the cylinder space is determined by This relates to a solid oxide fuel cell characterized in that the gas permeation amount is smaller than that of a portion of the body facing downstream of the gas flow.

(Example) FIG. 1 is a longitudinal cross-sectional view of a 5OFC according to an example of the present invention, and FIG. 2 is a cross-sectional view taken along the line E in FIG. 1. 5O in this example
In the FC, the same reference numerals are given to the same functional members as in 5OFC in FIG. 9.

In 5OFC in FIG. 1, the side circumferential surface ib of the oxidizing gas supply pipe 1
A plurality of circular holes 2 having the same diameter are arranged in the longitudinal direction, and flat ribs 3 are arranged in two rows between the side peripheral surface 1b of the oxidizing gas supply pipe 1 and the porous support pipe 4. It is set up. Therefore, the oxidizing gas supplied into the oxidizing gas supply pipe 1 is blown out sequentially from each circular hole 2 as shown by the arrow C, and after being used for power generation, the oxidizing gas is discharged from the oxidizing gas supply port 1a at the tip. is mixed with the exhaust gas chamber 19 as shown by the arrow.
is discharged to.

Further, the open porosity of the bottomed porous support tube 4 is reduced on the upstream side of the oxidizing gas flow flowing in the cylinder interior space 29, and the open porosity of the bottomed porous support tube 4 is reduced to a predetermined range on the downstream side. Made it bigger.

The air electrode 5 is made of doped or undoped LaMnOa, CaMnO3, LaNiO
a, LaCo0a.

It can be manufactured from LaCrOs or the like, and strontium-doped LaMnOs is preferable. The solid electrolyte 6 can generally be manufactured from yttria-stabilized zirconia or the like. Fuel electrode 7
is generally a nickel-zirconia cermet or a cobalt-zirconia cermet.

According to the 5OFC of this embodiment, the following effects can be achieved.

(1) Conventionally, as described above, in the cylinder space 29, as the distance from the oxidizing gas supply port increases, the oxidizing gas concentration decreases, the electrochemical reaction decreases, and the temperature also decreases accordingly. That is, when released from the 4° opening of the 5OFC element, for example, about 2 of the oxygen in the oxidizing gas
Approximately 0% was consumed, and the electrode reaction was highly non-uniform. This tendency increased as the length of the 5OFC element became longer.

On the other hand, in this embodiment, since a plurality of circular holes 2 are sequentially provided in the side circumferential surface 1b of the oxidizing gas supply pipe 1 in the longitudinal direction, each circular hole 2 functions as an oxidizing gas supply section.
Fresh oxidizing gas is supplied from each circular hole 2, respectively.

Therefore, fresh oxidizing gas is supplied throughout the cylinder space 29 and mixed with the oxidizing gas whose concentration has already decreased, which also adds to the turbulence of the mixed gas flow, reducing the oxygen concentration gradient. I can do something.

Furthermore, it is also important to change the open porosity of the bottomed porous support tube 4 from the bottomed portion 4a side to the end portion 4b side of the power generation portion within a predetermined range.

Specifically, first, FIG. 10 shows a calibration curve showing the relationship between the average open porosity of the bottomed porous support tube and the amount of oxidizing gas permeation. However, in the graph of FIG. 1O, the amount of oxidizing gas permeation when the average open porosity of the bottomed porous support tube is 35.0% is set as 100.0, and is expressed as a relative ratio. As can be seen from FIG. 10, there was a nearly linear relationship between the two.

Then the length 3000 as shown in Fig. 1 and Fig. 9.
+nm bottomed porous support tubes were each prepared, and an air electrode, a solid electrolyte, and a fuel electrode were formed thereon to fabricate a 5OFC as shown in FIGS. 1 and 9.

And the 5OFC element according to the present invention and the conventional 5OFC element
Each C element is installed in the battery reaction chamber 2o, the battery reaction chamber 20 is heated to 1000°C, and then the oxidizing gas supply pipe 1
Air was supplied through the fuel inlet hole 10a, and methane was supplied through the fuel inlet hole 10a at a constant flow rate, thereby causing a reaction between oxygen ions and methane on the surface of each 5OFC element fuel electrode.

As shown in FIGS. 1 and 9, the measurement positions PI are obtained by dividing the straight line portion of each of the five OFC elements 40 into seven equal parts.

P2. P3. P4. P5. P6. P7. P
In step 8, measure the surface temperature of the fuel electrode during the reaction with a thermocouple,
Furthermore, at the same time, P.I.

P2. P3. P4. P5. P6. P7. P
The oxygen concentration at each position in the cylinder space 29 corresponding to position 8 was measured with a 0.2 meter. After that, it was cooled to room temperature, and PI, P2. P3゜P4. P5. P6. P
7. The open porosity of the bottomed porous support tube 4 at P8 was measured.

Then, the amount of oxidizing gas permeation at each position is calculated from the measured value of the resolved porosity at each position and the calibration curve in Figure 10, and then the product of the amount of oxidizing gas permeating and the oxygen concentration at each position is calculated. The amount of oxygen permeation at each position was determined. These results are shown in Tables 1, 2, and 3 below.

Table 1 shows the results when the open porosity in the longitudinal direction of the bottomed porous support pipe 4 is almost constant and air is supplied from the oxidizing gas supply port 1a of the oxidizing gas supply pipe 1 (No. 9 figure).

In Table 2, the open porosity in the longitudinal direction of the bottomed porous support pipe 4 is increased in the portion facing the downstream side of the flow of oxidizing gas, and the oxidizing gas supply port 1a of the oxidizing gas supply pipe l is The results are shown below.

In Table 3, the open porosity in the longitudinal direction of the bottomed porous support tube 4 is increased in the portion facing the downstream side of the oxidizing gas flow, and the oxidizing gas supply port 1a and the side circumference of the oxidizing gas supply tube l are Side 1
The results are shown when air is supplied from the circular hole 2 in b (Fig. 1).

Table 1 shows that near P8, the amount of oxygen ions supplied to the fuel electrode surface is large, the amount of reaction with methane in the fuel gas is large,
As a result, the fuel electrode surface temperature is significantly higher than the ambient temperature (1000° C.) of the cell reaction chamber 20. And P7. P6. P5. As we move from P4 to the downstream side, the amount of oxygen ions supplied to the fuel electrode surface at each position decreases, and the amount of reaction between the fuel gas and methane decreases, and as a result, the fuel electrode surface temperature at each position decreases. is decreasing.

In Table 2, the difference in fuel electrode surface temperature between PI and P8 has been greatly improved, making it extremely practical. However, in this example, a very long element of 3 m was used. Therefore, there are still some insufficiencies in achieving uniform power generation with a 5OFC element.

On the other hand, in Table 3 showing the results of measurement using a 5OFC element using the support tube 4 manufactured according to the present invention and supplying air from the gas supply port 1a and each circular port 2 of the gas supply tube 1, P1 to Since the temperature of the surface of the fuel electrode at each position of P8 is higher than the ambient temperature of the cell reaction chamber 20 and approximately the same temperature, it can be seen that power is generated almost uniformly within the 5OFC element. In addition, since the battery reaction occurs at a nearly uniform temperature in the longitudinal direction of the 5OFC element, the 5OFC
It is possible to prevent the occurrence of cracks in the C element, improving reliability during long-term use.

Next, Table 4 shows the relationship between the open porosity and mechanical strength of the bottomed porous support tube. However, in Table 4, the bending strength when the average open porosity of the bottomed porous support tube is 35% is set as 100, and expressed as a relative ratio.

Table 4 When the open porosity exceeds 50%, the strength of the porous support tube 4 is only about 7096 compared to the strength when the open porosity is 35%, and the reliability during long-term use as a 5OFC element decreases. Therefore, the open porosity in the longitudinal direction of the porous support tube 4 is set to 50% or less, and the oxidizing gas is supplied from the circular hole 2 on the side circumferential surface of the oxidizing gas supply tube 1 to increase the oxygen concentration.
It is important to make the battery reaction uniform in the longitudinal direction of the C element.

As described above, according to the 5OFC of this embodiment, the strength of the 5OPC element can be maintained high, the oxygen concentration in the oxidizing gas in the cylinder space 29 can be made uniform, and the bottomed porous support inside the cylinder space 29 can be made uniform. By controlling the oxidizing gas permeability of the tube 4 and skillfully combining these, it is possible to correct the non-uniformity of the electrode reaction.

As a result, heat generation is made uniform throughout the bottomed porous support tube 4, thermal strain stress is reduced, cracks are prevented, the life of the 5OFC element 40 is extended, and power generation efficiency is improved. It can be done.

) In the 5OFC with the structure shown in Fig. 9, the oxidizing gas supply;
Since the and 5OFC element 40 are separate bodies, the cylinder space 29
It was difficult to accurately position the oxidizing gas supply pipe 1 within the interior. Therefore, the position of the oxidizing gas supply pipe l changes in the cylinder interior space 29, so that the flow of the oxidizing gas rising between the outer peripheral surface of the oxidizing gas supply pipe l and the inner peripheral surface of the porous support 4 changes. There were problems such as variations in the performance of each cell.

On the other hand, in this embodiment, the oxidizing gas supply pipe l and the 5OF
Since it is connected to the C element 40 by the flat plate-like rib 3 and has an integral structure, the oxidizing gas supply pipe l can be reliably positioned within the cylinder space 29, and the oxidizing gas supply pipe l and the 5OFC element 40 can be connected with each other. There will be no variation in performance due to relative position changes between the two. Moreover, since it has a shape that extends radially from the flat rib 3 or the oxidizing gas supply pipe l, the 5OFC
The mechanical strength of the element 40 is also significantly increased in terms of structural mechanics.

It is to be noted that it is more convenient to provide three or more rows of flat ribs 3 and to make the angle formed by each rib smaller than 180° in order to further increase the mechanical strength, particularly the radial crushing strength, of the 5OFC element.

As described above, in this embodiment, a difference is made in the open porosity of the bottomed porous support tube 4 between the bottomed part 4a and the end 4b of the power generation part. End portion 4b
It is preferable to gradually increase the open porosity as it approaches .

The open porosity of the bottomed porous support tube 4 is 20 to 20 at any part.
It is preferable to set it to 40%. Moreover, this pore diameter is 1
It is preferable to set it to 10 micrometers.

If the open porosity of the support tube 4 exceeds 50%, the mechanical strength of the support tube 4 will drop significantly, making it impossible to obtain reliability for long-term use as a 5OFC element. Moreover, if it is less than 20%, the amount of oxidizing gas permeation will be significantly reduced, and the power generation efficiency will be reduced, which is not preferable.

The difference between the open porosity in the bottomed portion 4a and the open porosity at the end 4b of the power generation portion is preferably 15% or less when the distance between the bottomed portion 4a and the end 4b of the power generation portion is 3 m.

In order to reduce the open porosity of the bottomed portion 4a of the bottomed porous support tube 4 and to provide a gradient in the size of the open porosity, it is preferable to manufacture the bottomed porous support tube 4 by the following method. .

(1) When manufacturing the bottomed porous support tube 4 by firing, hold the open end side of the bottomed tubular molded body of ceramics, hang the bottomed tubular molded body with the bottomed part facing down, and Attach a weight to it and hang it. As a result, a load is applied to the side of the bottomed tubular molded body near the open end, causing it to be slightly elongated, increasing the open porosity, and at the same time, since no load is applied to the bottomed side, the open porosity is reduced. I can do something.

The bottomed porous support tube 4 is assembled using a ceramic kiln tool as described above and fired in the kiln. Heating rate: 20-200℃/h
r, firing temperature 1400 to 1600°C1 firing temperature holding time 30 minutes to 10 hours, cooling rate 20 to 200°C/
The porosity is appropriately set within the conditions of hr according to the predetermined porosity of the support tube 4.

(2) The bottomed porous support tube is once fired, and after firing, the open pores of the bottomed porous support tube are impregnated with a filler to fill the open pores, and then dried or fired. At this time, the amount of impregnation on the bottomed side of the porous support tube is greater than the amount of impregnation on the open end side (by doing so, the open porosity on the bottomed side is reduced, and the open porosity on the open end side is increased. Make it bigger.

The above has described an example in which the amount of oxidizing gas permeation is controlled by controlling the open porosity of the bottomed porous support tube itself 4, but the amount of oxidizing gas permeation can be controlled by other methods.

That is, by applying slurry in a spiral shape to the inner circumferential surface and/or outer circumferential surface of a bottomed tubular molded body made of a ceramic material and sintering it, the amount of gas permeation in each part of the bottomed porous support tube 4 is reduced. It can be changed.

Specifically, when applying slurry strips in a spiral shape, the width of the slurry strips is increased on the bottomed side, and the width of the slurry strips is decreased (or decreased) as it approaches the open end.
By increasing the density of the slurry strips on the bottomed side and decreasing the density of the slurry strips as they approach the open end, the amount of oxidizing gas permeation on the bottomed section is reduced, and the oxidation rate decreases as it approaches the open end. It is possible to increase the amount of gas permeation. Further, the same effect can be obtained by reducing the particle size on the bottomed side and increasing the particle size as it approaches the open end.

Of course, by applying slurry over the entire inner and/or outer circumferential surface of the bottomed porous support tube after firing and changing the particle size of the slurry as described above, the bottomed porous support tube can be formed. The oxidizing gas permeability of the material may be controlled.

In the 5OFC shown in FIG. 3, instead of providing a plurality of circular holes as an oxidizing gas supply section on the side circumferential surface 1b of the oxidizing gas supply pipe l, an elongated rectangular slit 12 is provided, and fresh oxidizing gas is supplied from this slit 12. Let it flow.

A slit 12 is provided in each section defined by the flat rib 3.

In addition, similar to the 5OFC in FIG. 1, the bottomed porous support pipe 4
The open porosity in the bottomed part 4a of the end part 4b of the power generation part is
The oxidizing gas permeability at the bottomed portion 4a is made smaller (suppressed) than the oxidizing gas permeability at the end portion 4b of the power generation portion. The same applies to 5OFC in FIG.

In FIG. 4, a plurality of circular holes 22 are also provided on the side surface of the oxidizing gas supply pipe 1 as oxidizing gas supply parts, and
The diameter of the circular hole 22 is gradually increased from the side closer to the opening of the 5OFC element 40 to the bottomed part. This prevents a situation where a large amount of gas flows out and insufficient oxidizing gas is supplied to the area near the bottom.
By adjusting the diameter of the circular hole 22, the oxidizing gas concentration within the cylinder space 29 can be adjusted.

In the 5OFC shown in FIG. 5, a slit 32 is provided as an oxidizing gas supply section on the side surface of the oxidizing gas supply pipe 1, similar to the 5OFC shown in FIG. However, the width of the slit 32 is gradually increased toward the bottomed portion of the 5OPC element 40. By employing such a slit 32, the same effect as the example shown in FIG. 4 can be achieved.

1 and 4, when the circular holes 2 and 22 are aligned with the normal to the wall surface of the oxidizing gas supply pipe 1, the circular holes 2 and 22 are aligned with the normal to the wall surface of the oxidizing gas supply pipe 1.
From 22 the oxidizing gas flows out horizontally in FIG. Further, the direction of the circular hole 2.22 can be inclined at a predetermined angle with respect to the normal to the wall surface of the oxidizing gas supply pipe 1, and the direction of the longitudinal direction of the oxidizing gas supply pipe 1 (in FIG. When tilted in the radial direction (horizontal direction in Figure 1) of the oxidizing gas supply pipe l with respect to the normal to the wall surface, the oxidizing gas flows out to the left. Or it flows out to the right.

That is, as shown in FIG. 6, for example, the oxidizing gas supply port 42 provided on the side surface of the oxidizing gas supply pipe 1 is tilted, and the oxidizing gas is tilted toward the bottomed portion 4a as shown by arrow C, and is caused to flow out. Then, this oxidizing gas flow reaches the bottomed part 4 as shown by arrow B.
It collides with the oxidizing gas flow flowing from direction b, which disturbs the oxidizing gas flow and makes it easy to become a turbulent flow, so this stirring effect can further reduce the oxygen concentration gradient.

FIG. 7 is a partial sectional view showing an example in which the present invention is applied to a so-called multi-cell type 5OFC.

A plurality of air electrodes 15 are provided on the surface of the bottomed porous support tube 4 at predetermined intervals, and a solid electrolyte 16 and a fuel electrode 17 are sequentially coated on each air electrode 15. Adjacent air electrode 15 or interconnector 2
8 are electrically connected sequentially.

In the 5OFC shown in FIG. 8, instead of providing a circular hole or a slit on the side surface of the oxidizing gas supply pipe as an oxidizing gas supply part, the oxidizing gas supply pipe 51 is made of a porous breathable material, such as porous ceramics. A closing part 52 is provided at the bottom end of the oxidizing gas supply pipe 51 to block ventilation. Then, as shown by arrow A, oxidizing gas is supplied into the oxidizing gas supply pipe 51 to create a pressurized state, and the oxidizing gas supply pipe 51
The oxidizing gas inside is discharged from the side circumferential surface 51b toward the inside of the cylinder space 29 as shown by arrow E, and is used for power generation.

Therefore, since the oxidizing gas is supplied from the entire side peripheral surface 51b of the oxidizing gas supply pipe 51 and mixed, unlike the case where the oxidizing gas is supplied from the opening at the tip of the oxidizing gas supply pipe as shown in FIG. Similar to 5OPC in Figure 1, the cylinder space 29
The oxygen concentration within the tank is also made uniform.

Alternatively, the open porosity of the oxidizing gas supply pipe 51 can be made constant for each part, or the open porosity of the end 51c on the bottomed part side and the open porosity of the end 51d on the open end side of the power generation part. The rate can be different. In this case, by decreasing the open porosity at the end 51c on the bottomed portion side and gradually increasing the open porosity toward the open end side, the amount of oxidizing gas supplied to the bottomed portion 4a side can be reduced. Since it is possible to relatively increase the amount of fresh oxidizing gas supplied to the end portion 4b side of the power generation section, it is possible to prevent fresh oxidizing gas from concentrating on the bottomed portion 4a side. Even more effective.

The porous oxidizing gas supply pipe 51 is preferably made of zirconia, alumina, or the like. Further, the closing portion 52 can be made airtight or made of a breathable material, and the oxidizing gas can also be supplied from the tip side of the oxidizing gas supply pipe 5I.

In order to reduce the open porosity of the end 51c on the bottomed side of the porous oxidizing gas supply pipe 51 and to provide a gradient in the size of the open porosity, it is necessary to Similar methods can be implemented.

Furthermore, in FIG. 8, the entire oxidizing gas supply pipe 51 may be made of a porous material, or the oxidizing gas supply pipe 51 may be made of a porous material.
It is advantageous if only the inserted portion of the tube 1 that is inserted into the cylinder interior space 29 is made of a porous material, since no leakage of oxidizing gas occurs outside the cylinder interior space 29.

The above example can be modified in various ways. On each side, a fuel electrode 7 is provided outside the air electrode 5, or the electrode arrangement may be reversed. In this case, fuel gas is supplied to the cylinder interior space 29, and oxidizing gas is supplied to the outside.

In FIG. 1, the 5OFC element 40 is supported vertically, but the entire power generating device may be horizontal or may be tilted at a predetermined angle.

In the examples shown in FIGS. 1 to 7, the circular holes 2, 22 and slits 12, 32 on the side surface of the oxidizing gas supply pipe l are used as the oxidizing gas supplying section, or an oxidizing gas supplying section having another configuration is used. You may. For example, a large number of small holes may be provided randomly, and in this case, if the density of small holes increases as they approach the bottomed part,
The same effect as the example shown in FIGS.

(Effects of the Invention) According to the solid oxide fuel cell according to the present invention, since the gas supply section that supplies oxidizing gas or fuel gas to the cylinder space is provided at least on the side peripheral surface of the gas supply pipe, Fresh oxidizing gas or fuel gas is supplied from this side circumferential gas supply section and mixed with the gas whose concentration has already decreased, so that the oxygen and fuel concentration gradient in the cylinder space can be reduced. In addition, the amount of gas permeation in the portion of the bottomed cylindrical porous support facing the upstream side of the gas flow flowing through the cylinder space is made smaller than the amount of gas permeation in the portion facing the downstream side. The amount of gas that permeates through the bottomed cylindrical porous support on the upstream side is smaller than the amount of gas that permeates through the bottomed cylindrical porous support on the downstream side.

In this way, as a result of reducing the oxygen and fuel concentration gradient between the upstream and downstream sides of the cylinder space, and making the amount of gas permeation on the upstream side smaller than the amount of gas permeation on the downstream side, these Due to the synergistic effect, the amount of oxygen or fuel that permeates through the bottomed cylindrical porous support can be made uniform very effectively.
Non-uniformity of electrode reaction is corrected. This makes it possible to uniformize heat generation throughout the bottomed cylindrical porous support, reduce thermal distortion stress, prevent cracks, achieve a longer life of solid oxide fuel cells, and improve power generation efficiency. can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a 5OFC according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the E-I line in FIG. 1, FIGS. 3, 4, 5, 6, 7, Fig. 8 is a cross-sectional view showing 5OFC according to other examples, Fig. 9 is a cross-sectional view showing a conventional 5OFC, and Fig. 10 is a graph showing the average open porosity and oxygen permeation rate of a bottomed porous support tube. It is a graph showing a relationship. l... Oxidizing gas supply pipe 1a... Oxidizing gas supply port 1b... Side peripheral surface 2, 22... Circular hole 3
... Flat rib 4 ... Bottomed porous support tube 4
a... Bottomed part 4b... End of power generation part 5.15... Air electrode 6, 16... Solid electrolyte 7, 17... Fuel electrode 12.32...
Slit 29...Cylinder space 40.50...
・5OFC element 42... Slanted oxidizing gas supply port 51... Porous oxidizing gas supply pipe 51b... Side peripheral surface 51C... End 51d on the bottomed side... Open end of power generation part Side end 52...Occluded parts A, B, C, D, E...Flow of oxidizing gas Fig. 1 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8

Claims (1)

[Claims] 1. A solid oxide fuel cell element in which an air electrode, a solid electrolyte, and a fuel electrode are formed on the outer peripheral surface of a bottomed cylindrical porous support, and a solid oxide fuel cell element of this solid oxide fuel cell element. A solid oxide fuel cell having a gas supply pipe inserted into a cylinder space, wherein a gas supply section that supplies oxidizing gas or fuel gas to the cylinder space is connected to at least a side circumferential surface of the gas supply pipe. and the gas permeation amount of the portion of the bottomed cylindrical porous support facing the upstream side of the gas flow flowing through the cylinder space is determined by A solid oxide fuel cell characterized in that the amount of gas permeation is smaller than that of the portion facing the downstream side of the flow.