JP2003109626A - Cylindrical solid oxide fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system free from impairing the air-tightness of an oxidant distributor and an oxidant introduction pipe, and damaging a cell even in the operation of high temperature in a cylindrical solid oxide fuel cell. SOLUTION: In this cylindrical solid oxide fuel cell comprising an oxidant supply pipe 24 where an oxidant flows, an oxidant buffer chamber 8 connected to the oxidant supply pipe 24, and the oxidant introduction pipe 6 inserted into a hole formed on a bottom face of the oxidant buffer chamber, and connected to the oxidant buffer chamber by a collar part engaged with the hole, to supply the oxidant to the cells of the fuel cell, a side to be engaged with the hole, of the collar part is a projecting spherical face.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid oxide fuel cell, and more particularly to a tubular solid oxide fuel cell in which tubular solid oxide fuel cells are assembled.

[0002]

2. Description of the Related Art FIG. 4 is a vertical sectional view showing a general structure of a conventional tubular solid oxide fuel cell (hereinafter also referred to as a tubular cell). The cell 1 is a ceramic tube having an open upper end and a closed lower end (cylindrical shape with a bottom). The cross section of the cell 1 has a multi-layered cylindrical shape, and includes an air electrode 4, a solid oxide 3, and a fuel electrode 2.
Etc., each layer is laminated. The thickness of each layer of cell 1 is several μ
m-2.5 mm, and the required functions (conductivity,
It is formed of a ceramic material containing an oxide having air permeability, solid oxide, electrochemical catalytic property, etc. as a main component. When an oxidant gas (air, oxygen-rich gas, etc.) is flown inside the cell 1 and a fuel gas such as H ₂ , CO, CH ₄ is flowed outside the cell 1, O ₂ − ions move inside the cell 1 to generate electricity. A chemical reaction occurs, a potential difference is generated between the air electrode 4 and the fuel electrode 2, electricity is generated, and heat is also generated.

Inside the cell 1, an elongated oxidant introducing pipe 5 for supplying an oxidant is inserted. The oxidant introduction pipe 5 has its upper end portion which goes out from the oxidant distributor 6 at the upper part of the solid oxide fuel cell and enters the inside of the cell 1, and its lower end reaches near the bottom of the cell 1. From the lower end of the oxidant introduction pipe 5, the oxidant is supplied to the bottom of the cell 1. The oxidant supplied to the bottom of the cell 1 goes upward inside the cell 1 while contributing to the above-described power generation reaction. Outside cell 1,
Fuel supply chamber under solid oxide fuel cell (not shown)
From above, the fuel gas is supplied upward. The fuel gas flows upward outside the cell 1 while contributing to the above-described power generation reaction, and the fuel gas in the unreacted portion and the electrochemical combustion reaction products (CO ₂ , H ₂ O, etc.) in the cell portion are Enter the exhaust combustion chamber described above. The sensible heat after burning in the exhaust combustion chamber is used for the residual heat of the oxidant and fuel gas supplied to the fuel cell, or sent to a power generation system using a normal steam boiler turbine for power generation. It

Since the output of one cell is limited, when constructing an actual fuel cell system, a plurality of cells 1 are assembled to form a fuel cell module 11 for use. A general horizontal sectional view of the fuel cell module 11 is shown in FIG. The fuel cell module 11 is mainly composed of a cell assembly 12 in which a plurality of cells 1 are electrically connected and arranged, a heat insulating material layer 13 arranged around the cell assembly 12, and a module container 14. Module container 1
In some cases, a heat insulating material layer may be further provided around the circumference of 4. In addition, there is a fuel cell module including a plurality of cell assemblies. FIG. 5 shows a fuel cell module composed of one cell assembly.

Also in the fuel cell module, as described above, the oxidant introducing pipe 5 is inserted in each cell, and the oxidant introducing pipe 5 is disposed in the upper part of the solid oxide fuel cell. The oxidant is supplied to the inside of the cell 1 by exiting from the vessel and entering the inside of the cell 1.

[0006]

In the conventional solid oxide fuel cell, whether the oxidizer distributor buffer chamber bottom surface 9 and the oxidizer introduction pipe 5 are integrally fixed as shown in FIG.
As shown in Fig. 2, both the lower surface of the collar 20 at the upper end of the oxidant introduction pipe and the bottom surface of the oxidizer distributor buffer chamber 9 are made in a flat shape, and a contact force is given by the dead weight or a pressing force of a spring to seal the oxidizer distributor Is kept. Generally, in the oxidizer distributor, the temperature of the exhaust combustion chamber on the outer surface is as high as 300 ° C. to 600 ° C. with respect to the temperature of the oxidant on the inner surface, and the thermal expansion amount of the inner surface of the oxidizer distributor buffer chamber is small and the thermal expansion of the outer surface is large. Therefore, the plane portion is transformed into a curved surface. FIG. 8 shows a state where the bottom surface 9 of the buffer chamber of the oxidizer distributor is deformed into a curved surface which is convex downward. In this situation,
The oxidant introduction pipe 5 is not parallel to the cell and is inclined obliquely, and the position of the lower end is deviated from the cell core to one side. As a result, the utilization efficiency of the entire cell is deteriorated due to the uneven pressure distribution of the oxidant inside the cell, and when the lower end of the oxidant introduction pipe comes into contact with the inner surface of the cell, the reaction force causes the upper end to rise as shown in FIG. Part of the fuel cell system is damaged by the fact that the flange part of the fuel cell floats up and the airtightness of the oxidizer distributor is impaired. This will greatly reduce efficiency and reliability.

According to the present invention, even if the bottom of the distributor buffer chamber cannot be kept horizontal due to the deformation of the bottom of the distributor buffer chamber due to the temperature difference between the inside and the outside of the oxidizer distributor, the oxidizer introducing pipe is kept parallel to the cell. The purpose of the present invention is to provide an oxidizer distributor and prevent a decrease in efficiency of the entire fuel cell system.

[0008]

In order to achieve the above object, in the first invention, an oxidant supply pipe into which an oxidant flows, an oxidant buffer chamber connected to the oxidant supply pipe, A tubular solid oxide having an oxidant introduction pipe that is inserted into a hole on the bottom surface of the oxidant buffer chamber and is connected to the oxidant buffer chamber by a flange portion that engages with the hole and supplies the oxidant to the fuel cell unit. A cylindrical solid oxide fuel cell in which the side of the flange portion that engages with the hole has a convex spherical surface. According to the present invention, even if the bottom of the distributor buffer chamber cannot be kept horizontal due to the deformation of the bottom of the distributor buffer chamber due to the temperature difference between the inside and the outside of the oxidizer distributor, the cell can be maintained while maintaining the airtightness between the oxidizer introducing pipe and the oxidizer distributor. On the other hand, the oxidant introduction pipe can be kept parallel, and the efficiency of the entire fuel cell system can be prevented from lowering.

In the second invention, the oxidant supply pipe into which the oxidant flows, the oxidant buffer chamber connected to the oxidant supply pipe, and the hole inserted through the bottom surface of the oxidant buffer chamber In a tubular solid oxide fuel cell having an oxidant introducing pipe connected to the oxidant buffer chamber by an engaging collar and supplying the oxidant to the fuel cell, the tubular solid oxide fuel cell is engaged with the collar of the hole. According to the present invention, which provides a solid oxide fuel cell having a concave spherical surface around the hole on the side of the distributor, the distributor buffer chamber bottom surface is deformed by the temperature difference between the inside and outside of the oxidizer distributor, as in the first invention. Even if the bottom of the oxidizer cannot be kept horizontal, the oxidizer inlet pipe can be kept parallel to the cell while maintaining the airtightness of the oxidizer inlet pipe and the oxidizer distributor, reducing the efficiency of the entire fuel cell system. Can be prevented.

In the third invention, the oxidant supply pipe into which the oxidant flows, the oxidant buffer chamber connected to the oxidant supply pipe, and the hole formed at the bottom of the oxidant buffer chamber are inserted into the oxidant buffer chamber. In a cylindrical solid oxide fuel cell having an oxidant introducing pipe connected to an oxidant buffer chamber by an engaging collar and supplying an oxidant to a fuel cell, the tubular solid oxide fuel cell is engaged with the hole of the collar. There is provided a cylindrical solid oxide fuel cell in which the radius of curvature of the convex spherical surface is the same as that of the convex spherical surface, and the radius of curvature of the concave spherical surface is substantially the same around the hole on the side that engages with the flange portion. According to the present invention, like the first and second inventions, even if the bottom of the distributor buffer chamber cannot be kept horizontal due to the deformation of the bottom of the distributor buffer chamber due to the temperature difference between the inside and the outside of the oxidizer distributor, It is possible to keep the oxidant introduction pipe parallel to the cell while maintaining airtightness with the oxidant distributor, and prevent a decrease in the efficiency of the entire fuel cell system.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the configuration of an embodiment utilizing the present invention will be described with reference to the drawings. FIG. 1 shows the entire fuel cell of the present invention. In FIG. 1, a tubular solid oxide fuel cell unit 1 is a ceramic tube with an open upper end and a closed lower end, and an oxidant gas represented by air is flown inside and a fuel gas such as H2, CO, CH4 is flown outside. It is the part that generates electricity by electrochemical reaction. A plurality of cylindrical solid oxide fuel cell units 1 are bundled and electrically and physically connected between the cells by an electric conductor having high heat resistance and elasticity as represented by nickel felt.
Forming an aggregate. The heat insulating material layer 13 is disposed around the cell assembly, and has a role of a heat insulating material that does not allow the internal heat to escape to the outside and a function of a structure that supports the cell assembly and the oxidizer distributor 6 in the upper portion. The fuel distribution chamber 22 is a room partitioned below the cell assembly, and the fuel distribution chamber partition plate 23 is provided with a number of holes or slits for fuel distribution and is sent to the fuel distribution chamber 22. It has the role of distributing the fuel to each cell almost evenly. The exhaust combustion chamber 7 is a chamber partitioned by an exhaust combustion chamber partition plate 21 made of a porous material disposed at the upper end of the cell and the oxidizer distributor 6 at the upper part, and is used for the fuel that does not contribute to power generation. It has a role of passing a certain fixed amount through the exhaust combustion chamber partition plate 21 and burning it in the exhaust combustion chamber 7 to maintain the power generation operating temperature of the cell and enhance the utility value of the exhaust gas as heat. The oxidant distributor 6 includes an oxidant supply pipe 24, an oxidant buffer chamber 8,
The oxidizer is composed of the oxidant introduction pipe 5, and the oxidant sent from the outside by the oxidant supply pipe 24 is stored in the oxidant buffer chamber 8 and passed through each oxidant introduction pipe 5 to form a cylindrical solid oxide fuel cell 1 Has the role of supplying the oxidant evenly to the lower part inside. The oxidant introducing pipe 5 passes through a hole formed in the bottom surface 9 of the oxidant distributor 6, and is suspended from the oxidizer distributor bottom face 9 by a collar 20 fixed to the upper end of the oxidant distributor pipe 5.

Next, the operating state will be described. As described above, the inside is an oxidant gas represented by air, and the outside is H.
Fuel gas such as 2, CO, CH4, etc. is made to flow and the cell is set to 700
By maintaining the temperature from 1 ° C to 1100 ° C, power is generated by an electrochemical reaction. The oxidant gas is 40% by radiant heat generated from the cell during heat generation or heat exchange with exhaust gas.
While being heated from 0 ° C. to 700 ° C. and sent to the oxidizer distributor 6, in the exhaust combustion chamber 7 below the oxidizer distributor, the oxidizer heated from 700 ° C. to 1000 ° C. by the cell and the exhaust combustion chamber partition plate 21. As the fuel that has passed through is further burned, the atmosphere is always 1000 ° C. or higher. Therefore, inside and outside the oxidant distribution chamber 6, 300 to 600 ℃
Temperature difference occurs. As a result, the bottom surface 9 of the oxidizer distributor is deformed to be convex downward due to the difference in thermal expansion amount between the inner surface and the outer surface.

FIG. 2 is an enlarged view for explaining the embodiment of the present invention in the operating state, and shows a state in which the bottom surface 9 of the oxidizer distributor is tilted. Since the bottom surface of the collar 20 is a convex spherical surface, it can be automatically adjusted vertically downward by the weight of the oxidant introduction tube 5, and the contact portion between the oxidant introduction tube collar 20 and the oxidizer distributor bottom surface 9 Can be kept airtight. Therefore, it is possible to prevent a decrease in the efficiency of the entire system without impairing the original capability of the fuel cell.

FIG. 3 is an enlarged view for explaining another embodiment of the present invention in the operating state, and shows a state in which the bottom surface 9 of the oxidizer distributor is inclined. The upper surface of the bottom surface 9 of the oxidant buffer chamber around the hole through which the oxidant introduction pipe 5 is inserted is a concave spherical surface.
As in the case of FIG. 2, the airtightness of the contact portion between the oxidant introduction pipe collar 20 and the oxidant distributor bottom surface 9 can be maintained. Although not shown, the bottom surface of the collar 20 is a convex spherical surface, and the upper surface around the hole through which the oxidant introducing pipe 5 of the oxidant buffer chamber bottom surface 9 is made a concave spherical surface, and the radii of curvature of both spherical surfaces are substantially the same. If so, the sealing surface is brought into surface contact, so that the airtightness is further improved.

[0015]

The present invention has the following effects due to the above configuration. According to the first and second aspects of the present invention, even if the bottom of the distributor buffer chamber cannot be kept horizontal due to the deformation of the bottom of the distributor buffer chamber due to the temperature difference between the inside and the outside of the oxidizer distributor, the introduction of the oxidizer can be achieved. It is possible to keep the oxidizer introduction pipe parallel to the cell while maintaining the airtightness of the pipe and the oxidizer distributor, and prevent the efficiency of the entire fuel cell system from decreasing. Further, according to the third aspect of the present invention, it is possible to further improve the airtightness and prevent a decrease in the efficiency of the entire fuel cell system.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an oxidizer distributor and a fuel cell of the present invention as a whole.

FIG. 2 is a detailed vertical sectional view showing an embodiment of the oxidizer distributor of the present invention.

FIG. 3 is a detailed vertical cross-sectional view showing another embodiment of the oxidizer distributor of the present invention.

FIG. 4 is a vertical cross-sectional view showing a general configuration of a conventional tubular solid oxide fuel cell unit.

FIG. 5 is a horizontal sectional view showing a general configuration of a conventional fuel cell module.

FIG. 6 is a detailed vertical cross-sectional view showing details of a conventional oxidizer distributor.

FIG. 7 is a detailed vertical cross-sectional view showing details of a conventional oxidizer distributor.

FIG. 8 is a vertical cross-sectional view showing the oxidant distributor and the entire fuel cell in a state where the oxidant buffer chamber is deformed.

FIG. 9 is a detailed vertical cross-sectional view showing details of a conventional oxidizer distributor in a state where the oxidizer buffer chamber is deformed.

[Explanation of symbols]

1: Cylindrical solid oxide fuel cell 2: Fuel electrode 3: Solid oxide 4: Air electrode 5: Oxidizing agent introduction pipe 6: Oxidizer distributor 7: Exhaust combustion chamber 8: Oxidizer buffer chamber 9: Bottom of oxidizer distributor 10: Oxidizing agent introduction pipe collar part 11: Fuel cell module 12: Cell aggregate 13: Insulation layer 14: Module container 20: Oxidizing agent introduction pipe collar 21: Combustion chamber partition plate 22: Fuel distribution chamber 23: Fuel distribution chamber partition plate 24: Oxidant supply pipe

Continued front page    (72) Inventor Hiroaki Takeuchi             2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture             No. Totoki Equipment Co., Ltd. (72) Inventor Satoshi Matsuoka             2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture             No. Totoki Equipment Co., Ltd. (72) Inventor Susumu Aikawa             2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture             No. Totoki Equipment Co., Ltd. F-term (reference) 5H026 AA06 BB06 CV02 CX06 HH03

Claims (3)

[Claims] 1. A oxidant supply pipe into which an oxidant flows, an oxidant buffer chamber connected to the oxidant supply pipe, and a collar that is inserted into and engages with a hole on a bottom surface of the oxidant buffer chamber. A tubular solid oxide fuel cell having an oxidant introducing pipe connected to the oxidant buffer chamber by a portion to supply an oxidant to a fuel cell, and a side of the collar portion engaging with the hole. A cylindrical solid oxide fuel cell having a convex spherical surface. 2. An oxidant supply pipe into which an oxidant flows, an oxidant buffer chamber connected to the oxidant supply pipe, and a collar that is inserted into and engages with a hole on the bottom surface of the oxidant buffer chamber. A tubular solid oxide fuel cell having an oxidant introducing pipe connected to the oxidant buffer chamber by a portion to supply the oxidant to the fuel cell, and a side of the hole engaging with the flange portion. A cylindrical solid oxide fuel cell having a concave spherical surface around the hole. 3. An oxidant supply pipe into which an oxidant flows, an oxidant buffer chamber connected to the oxidant supply pipe, and a collar that is inserted into and engages with a hole on the bottom surface of the oxidant buffer chamber. A tubular solid oxide fuel cell having an oxidant introducing pipe connected to the oxidant buffer chamber by a portion to supply the oxidant to the fuel cell, and a side of the collar portion engaging with the hole. A cylindrical solid oxide fuel cell, wherein the radius of curvature of the convex spherical surface and the radius of curvature of the concave spherical surface around the hole of the hole that engages with the flange portion are substantially the same.