JP2003168469A - Solid electrolyte type fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent cracks in a cell while making it compact and raising power generation efficiency by obtaining high power generation output. <P>SOLUTION: Through a porous metal plate 6, which is inserted to each six recesses 8 arranged in the shape of a ring at the front and back surfaces of separators 7, each the single cells 5 are arranged by pressing, respectively, and the single cells 5 of six sheets are connected electrically in parallel. These separators 7 and the single cells 5 are laminated by turn, and a stack 4 is constituted. A fuel gas preheating pipe 17 and an oxidizer gas preheating pipe 16, which heat fuel gas and oxidizer gas beforehand, are arranged in the central penetration holes 7a of the separators 7, respectively. Each the gas beforehand heated even to the reaction temperature are supplied to recessed grooves 9 in each of the recesses 8 of each of the separators 7. The stack 4 is enclosed by the heat insulating material layer 20 and further, it is enclosed by a seal component 2 through the space 26 of its outside. The gas for heating is supplied inside of the heat insulating material layer 20 by the heating gas supplying component 25 and the gas for cooling is supplied to inside of the space 26 by cooling gas supplying component 27. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte fuel cell comprising, for example, a flat plate type solid electrolyte, and more particularly to a solid electrolyte fuel cell in which cells and separators are alternately laminated.

[0002]

2. Description of the Related Art Conventionally, a solid oxide fuel cell (SO) of a low temperature type which operates at a reaction temperature of 600 ° C. to 800 ° C.
As an example of FC), there is a stack type in which cells such as single cells and separators are alternately laminated. In this solid oxide fuel cell, a fuel gas and an oxidant gas are used as reaction gases, and a solid electrolyte plate made of ceramic or the like is sandwiched between positive and negative electrodes from both sides, and cells and separators are alternately laminated. ing. An oxidant gas such as oxygen or air is supplied to one of the concave grooves as a reaction gas flow path formed on the positive electrode side and the negative electrode side of the separator, and a fuel gas such as hydrogen is supplied to the other to cause a reaction. There is. In such a solid oxide fuel cell, a reaction gas supply manifold for supplying a reaction gas to the concave grooves which are the reaction gas flow paths on both sides of the separator is attached to the outer side of the stack in which the cells and the separators are stacked. As another solid oxide fuel cell, for example, JP-A-3-12
In this fuel cell, a reaction gas supply manifold is fitted in the vicinity of the central axis of the stack to distribute the reaction gas to the concave grooves on both sides of each separator. In any of the above-mentioned cases, the reaction gas is supplied from the outside to the reaction gas supply manifold via the pipe and distributed to the stacked separators of the stack.

[0003]

However, in these solid oxide fuel cells, since the cells (electrolytes) are made of ceramics, there is a drawback that they are easily cracked by a thermal cycle load. Especially when the normal temperature fuel gas and oxidant gas are supplied from the reaction gas supply manifold to the center of both sides of each separator and flowed to the outer peripheral side through the groove, the outer peripheral part is in a high temperature state due to the reaction heat. In addition, a temperature difference occurs between the central portion and the outer peripheral portion of the separator, which causes cracking due to the difference in thermal expansion. In order to prevent such a problem, it is conceivable to bury the reaction gas supply pipeline in the material of the thickness of the heat insulating material layer surrounding the stack, or to provide a heater inside the fuel cell. There is a problem that the battery becomes large and the cost becomes high. On the other hand, in order to achieve high output power generation, it is necessary to increase the power generation area per separator and cell to increase the extraction current value, but when manufacturing cells with ceramics, it is possible to manufacture the maximum with current technology. Dimensions are square plate type 150-200mm
There is a limit of about Φ150 mm for a square plate type and a circular plate type, and a size larger than this is likely to cause a problem such as waviness in the plate portion, and a flat ceramic plate cannot be manufactured. Therefore, it was difficult to increase the power generation output due to the increase in size of the cell. Therefore, in order to increase the power generation output, it is necessary to increase the number of stacked cells and separators, but if the outer diameter of the cells is set to a maximum of about Φ150 mm, the weight of one stainless steel separator is about 0.75 kg. Therefore, if the number of stacked layers is too large, the load stress applied to the lowermost cell becomes large, which causes cracking. Therefore, the number of cells and separators stacked alternately is about 10
About 20 steps was the practical limit.

In view of such circumstances, it is an object of the present invention to provide a solid oxide fuel cell capable of preventing cell cracking. Another object of the present invention is to provide a solid oxide fuel cell which is compact and capable of enhancing power generation efficiency and which can obtain a higher power generation output than ever before.

[0005]

A solid oxide fuel cell according to the present invention is a solid oxide fuel cell in which cells and separators are alternately stacked and a reaction gas is supplied to each separator. The reaction gas preheating tube for preheating the reaction gas before supplying the reaction gas to the separator is arranged inside the solid oxide fuel cell. The reaction gas to be supplied to the separator can be supplied into the separator in a state of being heated to the reaction temperature by supplying it to the reaction gas preheating tube provided in the solid oxide fuel cell and preheating it, It is possible to eliminate the temperature difference between the portion where the reaction gas is supplied and the other portion, and it is possible to suppress cracking of the separator. The reaction gas preheating tube includes a fuel gas preheating tube and an oxidant gas preheating tube.

A plurality of cells may be arranged on one separator and electrically connected in parallel with each other, and a reaction gas preheating tube may be arranged between the plurality of cells. A power generation area per separator without increasing the manufacturing size of the cell by providing a plurality of cells connected in parallel to one separator (two opposite surfaces or one surface of the separator) and stacking them alternately. Can be increased to increase the extraction current value and perform high-output power generation, and by disposing a reaction gas preheating tube between these cells, there is no waste of space and the solid electrolyte type has high power generation efficiency. A fuel cell can be obtained. Also, the stack formed by stacking cells and separators is surrounded by a heat insulating material layer,
A heating gas supply member for supplying a heating gas may be provided in the heat insulating material layer. By supplying the heating gas into the heat insulating material layer, the temperature of the chamber holding the stack can be raised to the reaction temperature, and the heating gas can preheat the reaction gas preheating tube. Moreover, if the power generation proceeds, the reaction gas preheating pipe can be heated to the reaction temperature by the reaction heat of the reaction gas even if the supply of the heating gas is stopped.

The outside of the heat insulating material layer may be surrounded by an outer member, and a cooling gas supply member for supplying a cooling gas may be provided in a space between the outer member and the heat insulating material layer. Even if the inside of the heat insulating material layer is heated by the reaction heat of the heating gas or the reaction gas, the cooling gas is supplied to the space between the outer member and the heat insulating material layer to lower the temperature, and the outer surface of the outer member is kept at room temperature. The solid electrolyte fuel cell can be manually contacted through the external member after being lowered to a certain degree. Moreover, the temperature can be controlled so that the inside of the heat insulating material layer is heated to a temperature higher than the reaction temperature and does not overheat by supplying the cooling gas. Further, the cooling gas may be pressurized so as to be able to flow into the inside through the heat insulating material layer. By forming a flow path through which the cooling gas flows from the space outside the heat insulating material layer into the heat insulating material layer, the reaction gas of the heating gas inside the heat insulating material layer and the reaction gas flows to the outside space through the heat insulating material layer. The temperature can be controlled by suppressing An exhaust pipe may be provided inside the heat insulating material layer, and the reaction heat of the cooling gas, the heating gas, or the reaction gas flowing into the heat insulating material layer can be discharged to the outside from the discharge pipe. It is possible to prevent the ambient temperature of the stack in the inner room from rising above the reaction temperature.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A solid oxide fuel cell according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 5.
FIG. 1 is an external plan view of a solid oxide fuel cell according to an embodiment, FIG. 2 is a side view of the same solid oxide fuel cell, FIG. 3 is a horizontal sectional view of the solid oxide fuel cell, and FIG. 4 is a solid oxide fuel. FIG. 5 is a vertical cross-sectional view of the cell, and FIG. 5 is a longitudinal sectional view taken along the line AA of FIG. 3 showing one unit cell of a stack of a solid oxide fuel cell and a separator corresponding to the single cell along the arrangement direction of the reaction gas supply pipe It is a side view. The solid oxide fuel cell 1 according to the embodiment has, for example, a substantially cylindrical appearance as shown in FIGS. 1 and 2, is covered with a substantially bottomed cylindrical seal member 2, and an upper portion of the seal member 2 is It is covered with the lid portion 3 and hermetically sealed. Seal member 2 having a lid 3
Constitutes an outer member. In the solid oxide fuel cell 1 shown in FIGS. 3 and 4, the stack 4 is formed inside the seal member 2, for example, in a substantially hexagonal column shape. Stack 4
Is a single cell 5 (cell; power generating cell) comprising a positive electrode and a negative electrode sandwiching a substantially disk-shaped solid electrolyte plate made of, for example, ceramics, and a porous metal plate (current collector) in the recesses on both sides. It has a basic structure in which, for example, 10 to 20 layers of, for example, substantially disk-shaped separators 7 with 6 interposed therebetween are alternately laminated. In particular, as shown in FIGS. 3 and 5, the separator 7 made of, for example, metal such as stainless steel is formed in a substantially hexagonal plate shape, and has a substantially ring shape in which a central through hole 7a is formed. A plurality of substantially disk-shaped recesses 8 for fitting the porous metal plate 6 around the central through hole 7a are formed on the front and back surfaces 7b and 7c facing each other in the thickness direction of the separator 7 at substantially equal intervals, for example, Six pieces are formed in a substantially ring shape. On the surface of each recess 8 on the front and back surfaces 7b and 7c, one or a plurality of substantially spiral recesses 9 are formed as reaction gas flow paths from the center to the outer periphery in plan view.

In each of the recesses 8 on the front and back surfaces of the separator 7, two tubular insertion holes 11 and 12 are provided at the center in the thickness direction from the outer peripheral side surface of the separator 7 toward the center of the recess 8.
And a fuel gas supply pipe 13a which communicates with the center side (inner side) edge of the concave groove 9 on the surface 7b side and which supplies a fuel gas such as hydrogen gas from the outside is fitted into one of the insertion holes 11. Has been inserted. The groove 9 constitutes a fuel gas flow path. An oxidant gas supply pipe 14a, which communicates with the center side (inner side) edge of the concave groove 9 on the rear surface 7c side and supplies an oxidant gas such as air or oxygen gas from the outside, is fitted into the other insertion hole 12. ing. The groove 9 constitutes an oxidant gas flow path. These gas supply pipes 13a and 14a are provided for each recess 8. The front and back surfaces 7b, 7 of one separator 7
In each of the six concave portions 8 of c, the separator 7 and the six single cells 5 are alternately laminated with the six single cells 5 facing each other with the porous metal plate 6 interposed therebetween. Has been done. The negative electrode 5b of each single cell 5 is pressed into each recess 8 of the front surface 7b of the separator 7, and the positive electrode 5a of the single cell 5 is pressed into each recess 8 of the back surface, so that each separator 7 and the single cell 5 are laminated in the same direction. Has been done. Then, the six unit cells 5 arranged on the front surface 7b and / or the back surface 7c of the separator 7 are electrically connected in parallel, and are connected in series in the stacking direction as one unit cell group. Further, in the central through hole 7a of the laminated separator 7, for example, two cylindrical pipes having a space with a ring-shaped cross section are concentrically sealed and arranged, and the inner small-diameter pipe is a fuel gas. The preheating pipe 17 and the outer large-diameter pipe constitute an oxidant gas preheating pipe 16 such as air or oxygen gas. Each of the preheating pipes 16 and 17 has a reaction temperature of 600 ° C. for the internal fuel gas and the oxidant gas due to the reaction heat of the fuel gas and the oxidant gas of the solid oxide fuel cell 1 and the heating gas supplied from the outside. It is designed to be heated to about 800 ° C. A notch is provided on each side of each separator 7 of the stack 4 to form a fuel gas supply manifold pipe 18
And three oxidant gas supply manifold pipes 3 are alternately sandwiched and three manifold pipes 18 and 19 are provided.
Extend in the stacking direction of the separator 7.

Then, the heated fuel gas is supplied from the fuel gas preheating pipe 17 to the three fuel gas supply manifold pipes 18 through the fuel gas supply pipes 13, and the fuel gas supply manifold pipes 18 are stacked. The fuel gas is supplied to each groove 9 via the fuel gas supply pipes 13a, 13a branched into two for each separator 7. Similarly, the heated oxidant gas is supplied from the oxidant gas preheating pipe 16 to the three oxidant gas supply manifold pipes 19 via the oxidant gas supply pipes 14, and further, in each oxidant gas supply manifold pipe 19. The oxidant gas is supplied to each groove 9 via the oxidant gas supply pipes 14a, 14a branched into two for each separator 7. Next, the stack 4 is housed in a chamber 20A formed by a heat insulating material layer 20 having a bottom and a lid and having a substantially cylindrical shape. This insulation layer 2
For 0, an appropriate air-permeable heat insulating material having air permeability can be adopted. Further, the stack 4 in which the unit cells 5 and the separators 7 are alternately laminated has upper and lower ends thereof having substantially disk-shaped substrates 22a and 22b.
And is fixed to the upper lid 20a of the heat insulating material layer 20 via a holding spring 24 by a plurality of fastening bolts 23 ... Which are fixed by penetrating the upper and lower substrates 22a and 22b. In addition, a holding base 4a composed of legs is attached to the lower surface of the stack 4 so that the stack 4 is separated from the lower surface and the side surface of the heat insulating material layer 20. The holding table 4a is the heat insulating material layer 2
It is held on the bottom surface of the seal member 2 by penetrating 0. A seal member 2 is provided further outside the heat insulating material layer 20, and the heat insulating material layer 20 is spaced apart from the upper and lower surfaces and side surfaces of the seal member 2 to support a leg portion 20b that forms a space 26 around the entire circumference. Is provided. Seal member 2 and heat insulating material layer 20
A heating gas supply member 25 is disposed so as to penetrate through the chamber, and its supply port 25a is opened in the vicinity of the bottom of the room 20A made of the heat insulating material layer 20. The heating gas supply member 25 heats the stack 4 to a reaction temperature of about 600 ° C. to 800 ° C. when the solid oxide fuel cell 1 is started.

Further, a supply port 27a of a cooling gas supply member 27 is provided in the space 26 between the seal member 2 and the heat insulating material layer 20, and the compressed air at room temperature is used as a cooling gas from the supply port 27a. By supplying the gas to the inside, the temperature in the space 26 is cooled to 100 ° C. or less, and the outer surface of the seal member 2 is cooled to a temperature at which a person can contact. Moreover, the compressed air flows through the heat insulating material layer 20 into the room 20A. A discharge pipe 31 (see FIGS. 1, 2 and 3) for discharging the heating gas, compressed air and the like is provided near the upper lid 20a in the room 20A of the heat insulating material layer 20 and is discharged to the outside through the seal member 2. It can be used for hot water supply systems. From the outside of the seal member 2, the heat insulating material layer 2
0 through the fuel gas preheating pipe 17, the oxidant gas preheating pipe 16
A fuel gas pipe 28 and an oxidant gas pipe 29, which supply the fuel gas and the oxidant gas at room temperature, respectively, are provided therein.
Further, a pair of electrode lead-out terminals 30a and 30b are provided so as to project from the lid portion 3 of the seal member 2 to the outside. The electrode lead-out terminals 30a, 30b are connected to the separators 7, 7 at the upper and lower ends of the stack 4, respectively.

The solid oxide fuel cell 1 according to this embodiment has the above-mentioned structure, and its operation will be described below. First, at the time of startup, the solid oxide fuel cell 1 is normally cooled to room temperature. Therefore, the heating gas is supplied to the stack 4 in the heat insulating material layer 20 through the heating gas supply member 25, and the temperature in the room 20A is set to 600 ° C. Heat to about 800 ° C. Then, the normal temperature fuel gas is supplied from the fuel gas pipe 28, and the normal temperature oxidant gas such as oxygen or air is supplied from the oxidant gas pipe 29 and sent to the fuel gas preheating pipe 17 and the oxidant gas preheating pipe 16, respectively. Since the heating gas is also circulated in the central through holes 7a of the stacked separators 7 of the stack 4, the oxidant gas and the fuel gas in each of the preheating pipes 16 and 17 have a temperature of about 600 ° C to 800 ° C. Heat to reaction temperature. The fuel gas is the fuel gas preheating pipe 17
From the fuel gas supply pipes 13 to the three fuel gas supply manifolds 18 and further connected to each of the separators 7 arranged in the stacking direction.
Is distributed and introduced into the concave groove 9 of each concave portion 8 provided on the surface 7b side. The fuel gas flowing into the inner end portion of the groove 9 flows in the groove 9 toward the outer peripheral side. Similarly, the oxidant gas is also distributed from the oxidant gas preheating pipe 16 to the three oxidant gas supply manifolds 19 via the oxidant gas supply pipe 14, and further, the oxidant gas supply pipes 14 a connected to each separator 7 are connected. , 8a on each side of the back surface 7c through the recesses 8a, 14a
It is distributed and introduced into the concave groove 9 of. The oxidant gas introduced into the inner end of the groove 9 flows in the groove 9 toward the outer peripheral side.

Oxygen contained in the oxidant gas moves in the form of oxygen ions inside the solid electrolyte plate of the single cell 5 from the positive electrode 5a side to the negative electrode 5b side, and the surface 7b side of the separator 7 on the negative electrode 5b side. And chemically react with hydrogen gas contained in the fuel gas. Due to the heat generated by this chemical reaction, the solid oxide fuel cell 1 is heated from the inside and a potential difference is generated between the positive electrode 5a and the negative electrode 5b. On the other hand, on the front surface 7b side of the separator 7, water vapor generated by a chemical reaction with unreacted fuel gas is discharged from a fuel gas discharge nozzle (not shown) provided on the outer peripheral surface of the separator 7, and the rear surface 7c side of the separator 7 is provided. Then, the unreacted oxidant gas is discharged from an oxidant gas discharge nozzle (not shown) also provided on the outer peripheral surface of the separator 7. The fuel gas and the oxidant gas discharged from both discharge nozzles are mixed, for example, on the outside of the separator 7, and the solid oxide fuel cell 1 is heated from the outside by the heat generated by the chemical reaction (combustion). Due to the reaction heat inside and outside the solid oxide fuel cell 1, the temperature inside the heat insulating material layer 20 rises to about 600 ° C. to 800 ° C., which is equivalent to the reaction temperature. In response to this, the introduction of the heating gas from the heating gas supply pipe 25 is stopped, and the fuel gas and the oxidant gas supplied from the fuel gas pipe 28 and the oxidant gas pipe 29 are fed into the fuel gas preheating pipe 17
And the solid oxide fuel cell 1 in the oxidant gas preheating tube 16
It is heated to the reaction temperature by the heat of reaction. In any case, the concave groove 9 of the separator 7 to which the fuel gas and the oxidant gas are supplied
Since there is no temperature difference between the inner side and the outer peripheral surface, cracking of the unit cell 5 can be suppressed.

The space 26 between the heat insulating material layer 20 and the seal member 2 is supplied with a cooling gas supply member 27 at an appropriate temperature, for example, compressed air at room temperature is supplied as a cooling gas to bring the temperature in the space 26 to 100. The temperature of the outer surface through the plate thickness of the seal member 2 can be suppressed to about room temperature, and there is no risk of burns or the like even if the user touches it by hand. Moreover, the compressed air passes through the heat insulating material layer 20 and forms a flow path for discharging together with the heating gas from the discharge pipe 31 in the room 20A. Therefore, the heating gas supply member 27
There is no problem that the heating gas supplied from the backflows into the space 26 outside the heat insulating material layer 20 before the atmospheric temperature of the stack 4 is sufficiently raised to the reaction temperature. At the time of starting, the temperature around the stack 4 in the room 20A can be reliably raised to the reaction temperature.

As described above, according to the solid oxide fuel cell 1 of the present embodiment, one separator 7 is provided.
Since the six single cells 5 are arranged in parallel on the front and back surfaces 7b and 7c and connected in series in the stacking direction, the power generation area can be increased and the extraction current value can be increased to achieve high output power generation. it can. Moreover, in the stack 4, the fuel gas preheating pipe 17 and the oxidant gas preheating pipe 16 are arranged in the central through hole 7a of the separator 7 and preheated to a temperature equivalent to the outer peripheral side temperature of the stack 4 and then the separator 7 Since the gas is supplied to the inner end of the concave groove 9 in each concave portion 8, the structure is compact, and there is no difference in temperature between the inside and the outer peripheral side of the separator 7, which does not cause cell cracking. Can improve the service life of. At the start of power generation, the heating gas supply member 25 can be used to raise the ambient temperature of the stack 4 to the reaction temperature, and quick and efficient power generation can be performed. Further, a space 26 between the heat insulating material layer 20 and the seal member 2 outside the heat insulating material layer 20.
By supplying compressed air to the outside, the outside of the seal member 2 can be cooled to about room temperature, and the insulating layer 20 can be compressed by compressed air.
By forming a flow path for exhausting from the exhaust pipe 31 through the room 20A inside, it is possible to prevent the reaction temperature (power generation temperature) from rising too much by releasing heat in the stack 4 and control the reaction temperature.

In the above-described embodiment, the single cells 5 arranged in parallel on the front and back surfaces 7b and 7c of the single separator 7 are set to six pieces, but the number of single cells 5 is not limited to this. You can arrange cells. Further, the fuel gas preheating pipe 17 and the oxidant gas preheating pipe 16 arranged in the central through hole 7a of the separator 7 are concentrically overlapped with each other, but the present invention is not limited to this, and the concentric and parallel arrangements are made. It may be provided, or may be provided on the outer peripheral side of the stack 4 instead of in the central through hole 7a. In any case, the fuel gas and the oxidant gas may be supplied to the preheating pipes 17 and 16 at the same temperature as the outer peripheral side of the stack 4 and distributed near the inner center of the recess 8. Further, the supply position of the fuel gas or the oxidant gas into the groove 9 is not limited to the inner end portion of the groove 9 and can be supplied from an appropriate position. The fuel gas and the oxidant gas form a reaction gas.

[0017]

As described above, in the solid oxide fuel cell according to the present invention, the reactive gas preheating tube for preheating the reactive gas before supplying the reactive gas to the separator is arranged inside the solid oxide fuel cell. Therefore, the reaction gas can be supplied to the separator while being heated to the reaction temperature, and the temperature difference between the reaction gas supply part in the separator and other parts can be eliminated to prevent cell cracking. it can.

Further, since a plurality of cells are arranged in one separator and are electrically connected in parallel to each other, and the reaction gas preheating pipe is arranged between the plurality of cells, the power generation area is increased. Therefore, it is possible to increase the extraction current value and obtain a compact solid oxide fuel cell without wasting space. Further, since the stack formed by stacking the cells and the separator is surrounded by the heat insulating material layer, and the heating gas supply member for supplying the heating gas is provided in the heat insulating material layer, the internal temperature is raised to the reaction temperature. In addition, the reaction gas preheating tube can be preheated. Moreover, if the power generation proceeds, the reaction gas preheating pipe can be heated by the reaction heat of the reaction gas. Further, since the outside of the heat insulating material layer is surrounded by the outer member, and the cooling gas supply member for supplying the cooling gas is provided in the space between the outer member and the heat insulating material layer, the outer surface of the outer member is kept at about room temperature. Can be reduced to
Moreover, the temperature can be controlled so that the inside of the heat insulating material layer does not rise above the reaction temperature and do not overheat. In addition, the cooling gas is pressurized and allowed to flow through it through the heat insulating material layer, so that the reaction heat of the heating gas and reaction gas inside the heat insulating material layer is prevented from flowing back into the space through the heat insulating material layer. Temperature control.

[Brief description of drawings]

FIG. 1 is an external plan view of a solid oxide fuel cell according to an embodiment of the present invention.

FIG. 2 is an external side view of the solid oxide fuel cell shown in FIG.

FIG. 3 is a plan view showing an internal structure of a solid oxide fuel cell.

FIG. 4 is a vertical cross-sectional view showing the internal structure of a solid oxide fuel cell.

FIG. 5 shows one cell of a stack of a solid oxide fuel cell stack and a separator portion corresponding thereto in FIG. 3 along line A- along the direction of arrangement of a fuel gas supply pipe and an oxidant gas supply pipe.
It is a vertical sectional view taken along line A.

[Explanation of symbols]

1 Solid oxide fuel cell 2 Seal member (outer member) 5 single cells 7 separator 7a through hole 8 recess 9 groove 16 Oxidizer gas preheating pipe (reaction gas preheating pipe) 17 Fuel gas preheating tube (reaction gas preheating tube) 20 Thermal insulation layer 25 Heating gas supply member 27 Cooling gas supply member

Claims (5)

[Claims] 1. A solid oxide fuel cell in which cells and separators are alternately stacked and a reaction gas is supplied to each separator, wherein the reaction gas is supplied before the reaction gas is supplied to the separators. A solid oxide fuel cell, characterized in that a reaction gas preheating tube for preheating is disposed inside the solid oxide fuel cell. 2. A plurality of cells are arranged on one of the separators and electrically connected in parallel to each other, and the reaction gas preheating pipe is arranged between the plurality of cells. The solid oxide fuel cell according to claim 1. 3. A stack in which the cells and the separator are laminated is surrounded by a heat insulating material layer, and a heating gas supply member for supplying a heating gas is provided in the heat insulating material layer. The solid oxide fuel cell according to claim 1 or 2. 4. The outside of the heat insulating material layer is surrounded by an outer member, and a cooling gas supply member for supplying a cooling gas is provided in a space between the outer member and the heat insulating material layer. The solid oxide fuel cell according to claim 3. 5. The solid oxide fuel cell according to claim 4, wherein the cooling gas is pressurized and can flow through the heat insulating material layer.