JP2005203256A - Solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power generation cell in which temporary repair can be carried out easily without stopping the operation even in the case breakage happens in the cell. <P>SOLUTION: The power generation cells 5 and separators 8 are laminated alternately to constitute a fuel cell stack. Then, in the vicinity of the fuel cell stack, a rod shaped body 21 is rotatably installed, provided with a conductive member 22 along the direction of the laminated layers. In the case the breakage arises in the power generation cells 5, the rod shaped body 21 is rotated to make the conductive member 22 contact the outer peripheral part of the neighboring upper and lower separators 8, 8, to make the broken power generation cells 5 electrically short circuited. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a solid oxide fuel cell having a structure in which power generation cells and separators are alternately stacked, and more particularly to an emergency repair mechanism in the event of damage to a power generation cell.

  Solid oxide fuel cells (SOFC) are being developed as third-generation fuel cells for power generation. Currently, three types of solid oxide fuel cells have been proposed: a cylindrical type, a monolith type, and a flat plate type, all of which have a solid electrolyte composed of an oxide ion conductor as an air electrode (cathode) from both sides. It has a laminated structure sandwiched between fuel electrodes (anodes). A fuel cell stack is configured by stacking a plurality of power generation cells composed of this laminate alternately with separators with a fuel electrode current collector and an air electrode current collector interposed therebetween.

As an example, the solid electrolyte layer is composed of stabilized zirconia (YSZ) or the like to which yttria is added, and the fuel electrode layer is composed of a metal such as Ni or Co or a cermet such as Ni—YSZ or Co—YSZ, and the air electrode layer. Is composed of LaMnO ₃ , LaCoO ₃ or the like, the fuel electrode current collector is composed of a sponge-like porous sintered metal plate such as a Ni-based alloy, and the air electrode current collector is a sponge-like porous material such as an Ag-based alloy. The separator is made of stainless steel or the like.

In the solid oxide fuel cell, an oxidant gas (oxygen) is supplied to the air electrode side and a fuel gas (H ₂ , CO, CH _4, etc.) is supplied to the fuel electrode side as a reaction gas. The air electrode and the fuel electrode are both porous layers so that the gas can reach the interface with the solid electrolyte.
Oxygen supplied to the air electrode side passes through the pores in the air electrode layer and reaches the vicinity of the interface with the solid electrolyte layer. At this part, electrons are received from the air electrode and ionized to oxide ions (O ²⁻ ). Is done. The oxide ions diffuse and move in the solid electrolyte layer toward the fuel electrode. Oxide ions that have reached the vicinity of the interface with the fuel electrode react with the fuel gas at this portion to generate reaction products (H ₂ O, CO _2, etc.), and emit electrons to the fuel electrode. This electron can be taken out as an electromotive force in an external circuit of another route.

  By the way, it is necessary for the solid oxide fuel cell to raise the temperature of the inside of the fuel cell module to a high temperature of a predetermined operation temperature of 700 to 1000 ° C. at the time of start-up (at the start of power generation). For this reason, at the time of start-up, if the temperature is not gradually raised while maintaining the uniform temperature of the entire battery module, a temperature distribution will be generated in the surface of the power generation cell, and the power generation cell may be damaged (cracked) by the thermal stress at that time is there. This phenomenon can also occur during the temperature drop process when the operation is stopped.

As described above, in a series fuel cell in which a large number of power generation cells are stacked with separators interposed therebetween, if any one of the large number of power generation cells is damaged, the resistance of the portion increases and the power generation performance is degraded. In other words, depending on the damaged state of the power generation cell, power generation cannot be continued.
The repair work of removing the damaged power generation cell and replacing it with a new power generation cell is extremely complicated and requires a long time until recovery, during which power supply is stopped.
Therefore, the applicants proposed an emergency repair method in the case where the power generation cell is damaged in the previous application. (See Patent Document 1)
JP 2003-109651 A

  In the above disclosed technique, when a power generation cell is damaged during operation, the power generation cell is short-circuited by surrounding the outer peripheral portions of the separators on both sides of the damaged power generation cell with a conductive member. By this repair work, it becomes possible to continue power generation in the power generation cells other than the damaged power generation cell and to supply power, thereby avoiding a power generation stop for a long time.

  However, in the above repair method, it is necessary to temporarily stop the operation of the fuel cell in order to perform an emergency process on the damaged power generation cell. It takes a lot of time to gradually lower the temperature of the fuel cell at a high temperature of 700 to 1000 ° C. so that temperature distribution does not occur. In addition, after the repair, it takes much time to raise the temperature for resuming the operation of the fuel cell as in the case of the temperature drop.

  Thus, although the repair method according to the disclosed technology can shorten the repair time of the fuel cell itself as compared with the replacement work of the damaged power generation cell, there is a disadvantage that it takes a lot of time to set the operating environment, There were still points to be improved.

  The present invention has been made in view of the above-described conventional problems, and in the event that a power generation cell is damaged, a solid oxide fuel cell capable of performing emergency repair without stopping operation. The purpose is to provide.

That is, according to the first aspect of the present invention, a fuel cell stack is configured by alternately stacking power generation cells and separators, and a solid gas that generates a power generation reaction by supplying a reaction gas into the fuel cell stack. In the oxide fuel cell, a rod-shaped body provided with a conductive member is rotatably disposed along the stacking direction of the fuel cell stack, and the conductive members are separated from each other by rotating the rod-shaped body. The predetermined power generation cell is configured to be electrically short-circuited.
In this configuration, since the damaged power generation cell can be short-circuited by an operation from outside the fuel cell, it is possible to avoid the stop of power generation due to repair work.

The present invention according to claim 2 provides the solid oxide fuel cell according to claim 1, wherein a plurality of conductive members are provided on the rod-shaped body, and a short circuit occurs according to the rotation angle of the rod-shaped body. It is characterized in that the power generation cell can be selected.
In this configuration, since a plurality of repair locations can be arbitrarily selected with an integral rod-like body (repair mechanism), the repair work is simple and the work time is short.

Further, the present invention according to claim 3 is the solid oxide fuel cell according to claim 1 or 2, wherein the rod-shaped body is a conductive member capable of short-circuiting the power generation cells in units. It is characterized by providing.
In this configuration, since the unit is a short circuit, the repair mechanism can be simplified, and the repair work is simple, so the work time is short.

  As described above, according to the present invention, the repair work of the damaged fuel cell stack can be performed while the fuel cell is continuously operated. Will not be stopped. Further, since the repair work can be performed by an external operation, the work is extremely simple and can be performed in a short time.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  1 is an exploded cross-sectional view showing the main part of the solid oxide fuel cell, FIG. 2 is an exploded perspective view of the main part, FIG. 3 is an explanatory view showing a repaired state of the fuel cell stack, and FIG. 4 is a repair mechanism. FIG. 5 shows a repair mechanism different from that shown in FIG.

First, the configuration of a solid oxide fuel cell to which the present invention is applied will be described with reference to FIGS.
1 and 2, reference numeral 1 denotes a fuel cell stack. The fuel cell stack 1 includes a power generation cell 5 in which a fuel electrode layer 3 and an air electrode layer 4 are disposed on both surfaces of a solid electrolyte layer 2, a fuel electrode current collector 6 disposed outside the fuel electrode layer 3, an air electrode The air electrode current collector 7 arranged outside the layer 4 and the separator 8 arranged outside the current collectors 6 and 7 constitute a single cell 10 and a plurality of the single cells 10 are stacked. It is a cylindrical body. In addition, the same thing can be used for each element which comprises these single cells 10 as before.

  The separator 8 has a function of electrically connecting the power generation cells 5 and supplying gas to the power generation cells 5. The fuel gas is introduced from the outer peripheral surface of the separator 8 to collect the fuel electrode of the separator 8. A fuel passage 11 that is discharged from a surface facing the electric body 6 and an oxidant passage 12 that introduces an oxidant gas from the outer peripheral surface of the separator 8 and discharges the gas from the surface facing the air electrode current collector 7 of the separator 8. Have. However, the separators 8 (8A, 8B) at both ends have either the passages 11 and 12.

As shown in FIG. 1, on the side of the fuel cell stack 1, a fuel manifold 15 that supplies fuel gas to the fuel passages 11 of the separators 8 through the connection pipes 13, and an oxidant passage 12 of each separator 8. An oxidant manifold 16 for supplying an oxidant gas through the connection pipe 14 extends in the stacking direction of the power generation cells 5.
Reference numeral 11 denotes a cylindrical housing in which a heat insulating material is arranged on the inner wall, and a solid oxide fuel cell is configured by disposing the fuel cell stack 1 having the above configuration therein.

  By the way, in this embodiment, as shown in FIG. 2, the emergency repair mechanism 20 when the power generation cell 5 is damaged is provided in the vicinity of the fuel cell stack 1. FIG. 3 shows the enlarged main part. The repair mechanism 20 of the present embodiment is composed of a rod-like body 21 made of an insulating material such as ceramic, and a short-circuit portion 22 made of a conductive member such as stainless steel provided on the rod-like body 21, and is a fuel cell. It is disposed in the vicinity of the stack 1 along the stacking direction.

  The rod-shaped body 21 is freely rotatable, and one end portion thereof protrudes from the housing 30 of the solid oxide fuel cell so that the rod-shaped body 21 can be rotated by an external operation. By rotating the rod-shaped body 21, the short-circuit portion 22 of the rod-shaped body 21 can be brought into contact with or separated from the outer peripheral portions of the adjacent upper and lower separators 8, 8.

  In the repair mechanism 20 having the above-described configuration, when one of the many power generation cells 5 constituting the fuel cell stack 1 is damaged during operation, the pair of separators 8 and 8 disposed at both ends of the damaged power generation cell 5. By electrically short-circuiting the gap with the short-circuit portion 22 of the repair mechanism 20, the defective power generation cell 5 can be electrically excluded and power generation can be continued with another normal power generation cell 5. In this case, since the current generated in the normal power generation cell 5 flows through the conductive short-circuit portion 22 at the damaged portion, power is continuously supplied to the load side.

  In this embodiment, although the short-circuit part 22 was made into the arrow shape, it should just be a shape which can contact the outer peripheral part of the separator 8 effectively, It is not limited to this, The contact area with the separator 8 is increased. Therefore, it is preferable to increase the thickness of the short-circuit portion 22. Moreover, in order to reduce the power loss at the short circuit location (repair location) as much as possible, in this embodiment, a silver mesh or the like having excellent electronic conductivity is welded to the portion where the short circuit portion 22 contacts the separator 8.

  The quality of the power generation cells 5 in the fuel cell stack 1 can be determined from the voltage of each power generation cell 5.

  As described above, in this embodiment, since the short-circuiting operation of the damaged power generation cell can be performed in the operating state by an operation outside the fuel cell, it is possible to avoid the stoppage of power generation due to the conventional repairing operation. In addition, the repair work is simple and the work time is extremely short.

  FIG. 4 shows the repair mechanism 20 provided with a plurality of short-circuit portions 22 in the length direction of the rod-shaped body 21, and each short-circuit portion 22 is shifted by a predetermined angle in the circumferential direction of the rod-shaped body 21. It is formed so that the normal power generation cells 5 are not short-circuited at the time of repair. In addition, since these short-circuit parts 22 are attached to the insulating rod-like body 21, they are in a state of being insulated from each other.

  In this configuration, since the power generation cell 5 that can be short-circuited can be arbitrarily selected depending on the rotation angle of the rod-shaped body 21, repair work is facilitated. In order to avoid an accident, the rod-shaped body 21 itself is made to be rotatable, and can be separated from the fuel cell stack 1 (in the direction of the left and right arrows in FIG. 4). The operation was performed at a position away from the fuel cell stack 1, and after setting a predetermined rotation angle, the fuel cell stack 1 was approached.

  Further, in this configuration, for example, an angle meter (not shown) is installed at the end of the rod-shaped body 21 protruding from the housing 30, and the power generation cell 5 corresponding to the rotation angle of the rod-shaped body 21 is at a glance. It is preferable to understand as follows.

  Further, as shown in FIG. 5, the short-circuit width in the stacking direction by the short-circuit portion 22 is increased so that the power generation cell 5 can be short-circuited in predetermined unit units (unit 1, unit 2... In FIG. 5). May be. Also in this case, of course, the turning operation of the rod-shaped body 21 can be operated from the outside of the housing 30. By setting the short circuit in units, the structure of the repair mechanism 20 can be simplified and the repair work can be simplified. The unit unit is preferably one unit for 5 to 10 single cells (number of outputs: W to 1 KW).

FIG. 3 is an exploded cross-sectional view showing a main part of the solid oxide fuel cell of the present embodiment. The exploded perspective view of the principal part same as the above. Explanatory drawing which shows the repair state of the fuel cell stack by the repair mechanism of this embodiment. The figure which shows a repair mechanism. FIG. 4 is an explanatory view different from FIG. 3 showing a repaired state of the fuel cell stack by the repair mechanism of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell stack 5 Power generation cell 8 Separator 21 Rod-shaped body 22 Conductive member (short-circuit part)

Claims (3)

In a solid oxide fuel cell in which a power generation cell and a separator are alternately stacked to constitute a fuel cell stack, and a reaction gas is supplied into the fuel cell stack to generate a power generation reaction.
A rod-shaped body provided with a conductive member is rotatably disposed along the stacking direction of the fuel cell stack, and the rod-shaped body is rotated to bring the conductive member into contact with both adjacent separators so that predetermined power generation is performed. A solid oxide fuel cell characterized in that the cell is electrically short-circuited. 2. The solid oxide fuel cell according to claim 1, wherein a plurality of conductive members are provided on the rod-shaped body, and a power generation cell that is short-circuited according to a rotation angle of the rod-shaped body can be selected. 3. The solid oxide fuel cell according to claim 1, wherein the rod-shaped body includes a conductive member capable of short-circuiting the power generation cell in units. 4.

Images