JP2008103298A - Fuel cell, structure for stack and power generating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an outside manifold type cell enabling; reduction in molten carbonate form cell cost, improvement in electrode effective area ratio in the cell and easy dissembling of an assembly cell, etc. <P>SOLUTION: The cell is composed by providing a narrow width and projecting platform shaped sealing part all over periphery part of a rectangular metal plate, storing a rectangular and flat plate shape cathode 37 inside a platform shape part of a cathode current-collecting board 31 with numerous small holes 34 on its interior bottom surface, installing an electrolyte plate 38 on top of the cathode 37 so that the total surface of the cathode current-collecting board 31 is covered as well as arranging to have a wet seal work by bringing into contact with the platform shape part in the periphery of the cathode current-collecting board. In addition, an anode 39 is installed above the electrolyte plate 38, a fuel gas passage 41 is arranged above the anode 39 and an anode current-collecting plate 44 composed of a rectangular thin metal plate is made to cover the fuel gas passage 41 from above. The cell composed thus has material cost and processing cost greatly reduced by having a small number of parts in a separator and making welding not necessary. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention belongs to the field of energy conversion devices, and relates to a fuel cell that directly converts chemical energy of a fuel into electricity. In particular, the structure of the molten carbonate fuel cell and stack has been completely changed, the cost of the cell and stack has been greatly reduced, and a low-cost fuel cell power generation facility has been realized. Contributing to the improvement of the environment is the main purpose of the present invention.

(1) FIG. 1 shows the components of a conventional molten carbonate fuel cell (hereinafter, MCFC is used as a synonym for a molten carbonate fuel cell).
FIG. 1A shows a bird's-eye view of the cell, and FIG. 1B shows side views of the cathode side and the anode side, respectively, but there is a slight difference from the viewpoint of explanation.
As shown in FIG. 1A, the basic constituent elements of one cell are: an electrolyte plate 1 in which ceramic powder is formed into a flat plate shape, and voids between the particles are filled with alkaline carbonate as an electrolyte; The cell has a structure in which the cell is in close contact with each other so that the electrolyte plate is sandwiched between the two electrode anodes and the cathode, the anode electrode 2 and the cathode electrode 3 being made of sintered metal powder or the like on both sides.
Usually, the cells are not used alone, but are used as a stack in which many cells are stacked and the cells are connected in series.
In this state, in addition to the above three components, a component called a separator is required.
The separator has a cathode corrugated plate 4 for forming a passage for flowing cathode gas (a gas containing oxygen and carbon dioxide in the case of MCFC) to the cathode electrode, and a passage for flowing anode gas (fuel gas such as hydrogen) to the anode electrode. At least three components of the anode corrugated plate 5 for forming and the center plate 6 for preventing mixing of the cathode gas and the anode gas are required.
In addition, mask plates 7 are used so that the anode gas and the cathode gas do not leak or mix through the side surfaces of the separator.
Further, as shown in FIG. 1B, a cathode current collector plate 8 and an anode current collector plate 9 are inserted between the cathode electrode and the cathode corrugated plate and between the anode electrode and the anode corrugated plate, respectively, as necessary.
These current collectors support the electrodes in strength and at the same time have a function of reducing the electrical resistance between the cells.
(2) FIG. 2 is a diagram for explaining a method of flowing necessary gases to the cathode electrode and the anode electrode of the conventional fuel cell.
FIG. 2A shows a system called an internal manifold type, in which a cathode inlet 12, a cathode outlet 13, an anode inlet 14, and an anode outlet 15 are provided on the outer side of the effective electrode surface 10 of the separator cell. The cell is provided with a resistance portion 11 for improving gas flow distribution and a seal portion 16 for preventing gas from leaking to the outside.
FIG. 2B shows a system called an external manifold type, in which four side surfaces of the rectangular effective electrode surface 17 are used as gas supply ports and gas discharge ports. The cathode inlet 20, the cathode outlet 21, and the anode inlet 22 are used. In addition to the anode outlet 23, the cell is provided with a seal portion 19 and, if necessary, a resistance portion 18 for improving gas flow distribution.
(3) FIG. 3 is a conceptual diagram of a conventional external manifold type stack.
A large number of cells 24 are stacked, a gas supply manifold 25 is provided on the side, heat insulating / insulating materials 26 are placed on the top and bottom, and integrated from above and below using a tightening device 27, a tightening rod 28, and a spring 29. Thus, the current 30 is extracted from the upper and lower ends of the cell.

(1) The conventional cell shown in FIG. 1 is the same as that of the present invention in that the basic component is composed of an electrolyte plate and two electrodes, a cathode and an anode, arranged so as to sandwich it from both sides. However, in the prior art, metal parts called separators for supplying anode gas and cathode gas to the anode electrode and the cathode electrode, respectively, have a very complicated structure, a large number of parts, and expensive materials were used. There was a disadvantage that most of the cell cost was occupied by the cost of this separator.
Furthermore, since the electrodes of the anode and the cathode are not strong in themselves, when the electrode is placed directly on the corrugated plate, the corrugated plate is a corrugated plate. Present and deforms when tightened. When the electrode is deformed, the adhesion between the cell constituent elements is deteriorated, and the cell performance is lowered. Therefore, in order to prevent the drawbacks, as shown in FIG. 1B, a cathode current collector plate 8 made of a flat plate having a large number of fine holes is inserted between the cathode electrode and the cathode corrugated plate. A similar anode current collector plate 9 is also inserted between the anode electrode and the anode corrugated plate.
Therefore, the separator is composed of a large number of elements such as a cathode current collector plate, a cathode corrugated plate, a center plate, an anode corrugated plate, an anode current collector plate, and a mask plate, and the metal necessary for manufacturing them. Sheet pressing and welding are very costly and time consuming processes.
Further, nickel is used for the material on the anode side in order to prevent corrosion due to the electrolyte, and the cost is high in terms of material cost.
In order to solve this problem, the present invention greatly reduces the number of parts of the separator, simplifies the structure of the parts, and at the same time reduces the processing cost, and further increases the cost of nickel. By not using a plate material, the material cost is reduced, and a cell with significantly low cost as a whole is realized.
(2) In the case of the internal manifold type cell shown in FIG. 2A, the cathode inlet 12, the outlet 13, the anode inlet 14, and the outlet 15 need to be provided outside the effective electrode surface of the separator. The area of the separator, which occupies most of the cost, is significantly larger than the effective electrode area of the cell, resulting in a major drawback of raising the cost of the cell. On the other hand, since the power generation reaction that occurs between the anode gas (fuel gas) and the cathode gas (gas containing oxygen and carbon dioxide) is an exothermic reaction, the temperature of the anode gas and the cathode gas is generally higher at the outlet than at the inlet. Becomes higher. Depending on what kind of temperature distribution is generated in the stack, thermal stress is generated accordingly.
In order to avoid the occurrence of complicated thermal stress, it is preferable that the anode gas and the cathode gas be cocurrent or counterflow, and the internal manifold type has an advantage that the flow of these gases can be freely selected. .
On the contrary, in the case of the external manifold type shown in FIG. 2B, since most of the separator has an effective electrode area of the cell, there is an advantage that the cost is reduced, but the anode gas and the cathode gas are limited to the orthogonal flow. Therefore, the temperature distribution in the stack becomes complicated, and there is a great disadvantage that the stack may be damaged by complicated thermal stress including twisting.
In response to these problems, the present invention reduces the cost by increasing the proportion of the effective electrode area in the separator, and at the same time is the most stable in terms of thermal stress and can increase the life of the stack. A new cell structure that can be used is devised.
(3) In the conventional stack shown in FIG. 3, a large number of cells are directly stacked and tightened with a strong force. The separator has a welded structure, and the electrolyte plate placed between the separator is bonded. As a result, once the stack is in operation, the cells are in close contact with each other and become an integral one. Therefore, even if the voltage of one cell in the stack deteriorates or damage such as partial cracking of the cell and gas leakage occurs, it is not possible to replace only that cell. .
In addition, the electrolyte filled in the electrolyte plate gradually decreases with time and the battery performance deteriorates. However, in the conventional stack, the stack cannot be disassembled into individual cells. Could not be replenished.
To solve this problem, the present invention devised a cell and stack structure capable of disassembling the stack, replacing a deteriorated cell, and replenishing the electrolyte, and prolonging the substantial life of the stack. The purpose is to further reduce costs.

Since the present invention is a novel structure that is completely different from the conventional cell and stack structures, it is difficult to describe [means for solving the problems] without understanding the contents thereof. DETAILED DESCRIPTION OF THE INVENTION First, an explanation of the present invention will be given with reference to the drawings that are supposed to be described in the Detailed Description of the Invention, in which [Means for Solving the Problems] will be explained. .
Here, description will be made based on the fuel cell corresponding to claim 2 or 5, and in the following [Best Mode for Carrying Out the Invention], various embodiments corresponding to claims 1 to 7 will be described. Summarize the differences.

(1) FIG. 4 shows the cathode current collector 31 of the present invention.
The overall shape is rectangular, and a thin metal flat plate is manufactured by press molding or the like. The entire peripheral portion has a base portion 33 that is convex upward and narrow, and the inside thereof is a cathode electrode storage portion 32. That is, the cathode electrode storage portion becomes a shallow concave portion with reference to the upper surface of the peripheral trapezoidal portion. A large number of small holes 34 are provided on the bottom surface of the cathode electrode storage portion. Cathode gas is supplied to the cathode electrode through the small holes. The upper surface of each peripheral platform 33 is flat and is provided for wet sealing with the electrolyte in contact with the electrolyte plate. A notch 36 is provided on the short side of the outer wall surface 35 of the trapezoidal portion around the cathode current collector plate, and serves as an inlet and an outlet for the cathode gas.

(2) FIG. 5 shows a cathode electrode 37, which is a rectangular flat plate, whose size is slightly smaller than the cathode electrode storage portion of the cathode current collector plate, and whose thickness is slightly thicker. It is made of a material that has both electronic conductivity and air permeability.
When this is housed in the cathode electrode housing portion of the cathode current collector plate, the height is substantially equal to the height of the base portion 33 around the cathode current collector plate, and the entire surface forms a plane having substantially the same height.

(3) FIG. 6 shows an electrolyte plate 38, which is a rectangular flat plate formed of a powder such as ceramics, and lithium carbonate (Li ₂ CO ₃ ) and potassium carbonate (K ₂ CO ₃ ) that are electrolytes in the gaps between the particles. ), A mixed salt such as sodium carbonate (Na ₂ CO ₃ ), and has ionic conductivity, insulating properties, and airtightness under the operating conditions.
In addition, this shape is almost the same as the projected area of the cathode current collector plate, covers the entire cathode electrode on the cathode current collector plate containing the cathode electrode, and supports each of the peripheral plates of the cathode current collector plate. Arranged so that the wet seal function by the electrolyte works in the operating state in contact with the shape portion.

(4) FIG. 7 shows an anode electrode 39 made of a material having electronic conductivity and air permeability.
The shape is a rectangular flat plate, and the area is slightly larger than the cathode electrode housing portion of the cathode current collector plate and slightly smaller than the anode electrode of the anode current collector plate and the fuel gas passage housing portion. In addition, although it is a rectangle when it sees as a whole, there is a notch 40 in each corner, and consideration is given so that the flow of fuel gas becomes good.
In a state where the anode electrode is disposed on the electrolyte plate, each peripheral portion of the anode electrode is designed so as to be outside the cathode electrode storage portion of the cathode current collector plate, and is disposed as such.
This is because, when the end portions of the cathode electrode and the anode electrode overlap each other, a shear stress acts on the electrolyte plate at that portion, and the electrolyte plate is likely to be damaged.

(5) FIG. 8 is a fuel gas passage 41 using a bridge screen formed from a flat metal plate, and [A] is an image of the bridge screen for reference. In this case, the shape of the bridge screen is a rectangle, a thin metal plate is pressed, the long side is cut, the short side is not cut, and is plastically processed into a bridge-like shape. Is a rectangular opening. The entire surface of the fuel gas passage in FIG. 8 is a bridge screen, and 42 shows one of the shapes. The shape of the fuel passage as a whole is rectangular, but a notch 43 is provided at each corner. A reforming catalyst is appropriately disposed in the space between the convex portions 42A of the bridge screen. This fuel gas passage is placed on the anode electrode so that the plane is on the bottom and the convex portion 42A is on the top.
Although FIG. 8 is illustrated as an integral rectangular flat plate, the purpose is to support the anode electrode, to collect current, and to function as a spacer as a fuel gas passage. May be.

(6) FIG. 9 shows an anode current collector plate 44, which is a thin metal flat plate processed by a press or the like. The lower surface 45 of the trapezoidal portion is flat and is in contact with the electrolyte plate so that a wet seal function by the electrolyte works under operating conditions. Further, the inside 46 of the trapezoidal portion is a housing portion for the anode electrode 39 and the fuel gas passage 41, and the shape thereof is rectangular. The shape is almost the same as the anode electrode and the fuel gas passage, and the height is slightly overlapped. It is substantially equal to the combined height, and has a large number of upward projections 46A on the ceiling surface. The reforming catalyst is appropriately filled inside the protruding portion. At both ends on the long side of the peripheral trapezoidal portion, there are portions 47 and 47A where the height of the trapezoidal portion is low, which are used as a fuel gas supply port to the anode electrode and an exhaust port from the anode. Is called. In each of these portions, an electrolyte plate support component 48 is disposed, and consideration is given to maintaining the gas passage so that the electrolyte plate is not deformed or broken. Further, a notch 50 is provided on the short side of the outer wall surface 49 of the trapezoidal portion, which serves as a cathode gas passage.
The anode current collector plate 44 is placed from above the fuel gas passage so that both are accommodated in the anode 46 and the fuel gas passage housing 46.

(7) The above has been described by placing the cathode current collector at the bottom and stacking sequentially on top of it in order to explain the configuration of one cell and the relationship between each component. The anode side and cathode side are assembled separately, and finally both are combined into one cell.
That is, the anode electrode of the anode current collector plate and the storage portion of the fuel gas passage are placed facing upward, and the bridge portion (convex portion) 42A of the bridge screen of the fuel gas passage is placed thereon, and the storage portion is placed thereon. An anode electrode is accommodated, and an electrolyte plate is placed thereon. On the other hand, the cathode electrode storage part of the cathode current collector plate is placed facing upward, and the cathode electrode is stored there. At this time, the cells are integrated by using an adhesive that temporarily bonds them together, and then inverted and placed on the electrolyte plate to complete the cell. The temporary adhesive used at this time disappears during operation, or at least uses no harm.

(8) FIG. 10A shows an assembled cross-sectional view of the cell. A cathode current collecting plate 31, a cathode electrode 37, an electrolyte plate 38, an anode electrode 39, a fuel gas passage 41, and an anode current collecting plate 44 are arranged in order from the bottom. The anode current collector plate has a fuel gas supply port 47 in a peripheral trapezoidal portion, and this opening portion is connected to an opening portion 54 of the fuel supply header 53 through an opening portion of the insulating and sealing material 52. From here the gas is supplied to the anode. FIG. 10B is a diagram for explaining the state of supply of fuel gas to the anode and the state of exhaust from the anode. There are fuel supply ports 53 at both ends of the upper portion of the cell, and exhaust ports 55 at both ends of the lower portion of the cell.

(9) In the fuel gas passage of the cell assembled as described above, a flat tube is formed by the anode current collecting plate and the electrolyte plate, and basically there is no leakage of the fuel gas to the outside. If fuel gas is allowed to flow through the fuel supply port 47, the fuel gas is supplied to the anode electrode. On the other hand, when a cathode gas is caused to flow outside the flat cell formed by the anode current collector plate and the cathode current collector plate, the cathode gas is supplied to the cathode electrode through a large number of openings of the cathode current collector plate.
Since the cells made in this way are a cathode current collector plate and an anode current collector plate made of metal on both sides, they are not in close contact with each other even if they are stacked, and each cell is independent. A projection 46A of the anode current collector plate is provided between the anode current collector plate and the cathode current collector plate, and this serves as a spacer as a cathode gas passage. Therefore, even if it is assembled and operated once as a stack, one cell is integrated by the electrolyte plate, but the cells are not bonded to each other. Can be dismantled.

(10) Since this cell does not have an internal manifold and basically has an effective electrode area except for the peripheral seal portion, the ratio of the effective electrode area to the total cell area is large.
Furthermore, the shape of the cell is a vertically long rectangle, and both the fuel gas and the air are long in the flow direction width, and the gas flow distribution is uniform without providing a resistance portion for improving the flow distribution. . Although FIG. 10 shows that the cell is vertically long, the aspect ratio does not appear to be very large, but since the fuel gas is supplied and discharged from both sides, the width of the cell is substantially halved. .
Further, since the width is narrow, the temperature difference between the central portion and the peripheral portion is small, and it is difficult to be damaged by hot spots or thermal stress.

(11) FIG. 11 is a conceptual diagram of a stack in which the cells of FIG. 10A are stacked.
Current extraction plates 57 are provided above and below the cell stack 56, and heat insulating and insulating materials 58 are provided above and below the plate. From the upper and lower sides, the whole is clamped by a clamping rod 62 via a spring 60 by a clamping device 59.
However, since each cell is a metal plate at the top and bottom, it will not be in close contact with each other, and if the fuel gas header and the clamping device are removed, each cell can be broken apart, so damage can be avoided. It is also possible to replace the received cell, thereby substantially extending the service life. Further, the electrolyte can be replenished through a large number of openings provided in the cathode current collector plate without being separated.
In FIG. 11, reference numeral 61 denotes a spring cover, 63 denotes a current extraction cable, and 64 denotes an inverter.

(12) FIG. 12 shows the arrangement of devices around the stack and the flow of cathode gas and anode gas. The stack 65 is arranged so that the fuel inlet header 53 is at the top and the anode exhaust header 55 is at the bottom. The fuel gas FG is supplied to the anode side of each cell via the fuel gas header 53. The fuel gas flows from top to bottom and is guided to the mixing chamber 68 via the anode exhaust header 55 at the bottom of the stack. On the other hand, the air AIR flows from the top to the bottom while being preheated by a flat air preheater 66 disposed so as to surround the periphery of the stack, and is guided from the lower part to the mixing chamber to be mixed with the anode exhaust. Next, combustible components in the anode exhaust are combusted in contact with the combustion catalyst 70 in the combustion chamber 69, and combustion gas containing CO ₂ and oxygen flows from the bottom upward through the passage on the cathode side.
That is, a counter flow system in which the fuel gas flows from the top to the bottom and the cathode gas flows from the bottom to the top is used. In general, since the power generation reaction is exothermic, both the anode gas and the cathode gas have a higher temperature at the outlet than the inlet, but in the counterflow, they cancel each other, so the entire stack is at the most uniform temperature and is due to thermal stress. It is a structure that is not easily damaged.
At this time, since the temperature of the cathode gas can be controlled by adjusting the fuel utilization rate, the temperature distribution of the stack can be maintained uniformly, thereby reducing the thermal stress applied to the stack.

(1) The cell structure of the present invention has an extremely small number of separator metal working plates per cell that has the greatest effect on the cost of the cell compared to conventional cells. Can be greatly reduced.

(2) The components of the cell used in the present invention are all simple rectangles, the metal processed plates can be formed by simple press processing, and the other porous components can be formed by a tape forming machine and a continuous firing furnace, requiring welding. There is nothing to do. Therefore, the processing time is short and the cell processing cost can be greatly reduced.

(3) Since the shape of the constituent parts of the cell of the present invention is a simple rectangle and the width is narrow, production facilities such as a press, a tape molding machine, and a continuous firing furnace are all equipped with small and narrow equipment. Less investment is required.

(4) The stack of the present invention has a structure in which a necessary number of cells are stacked and tightened with a clamping device. If the fuel gas header and the stack clamping device are removed, the stack can be disassembled into each cell and damaged. It is possible to replace the cell that has received the electrolyte or to replenish the electrolyte. In addition, the electrolyte can be replenished through the holes provided in the cathode electrode storage portion of the cathode current collector plate without having to separate each cell.

(5) Since the cell of the present invention has a long distance to the gas flow direction and a narrow width, the variation in the gas flow distribution is small even without providing a resistance portion for improving the flow distribution.

(6) The cell of the present invention is originally in a certain temperature range because the flow of the cathode gas and the anode gas is a counter flow, and the thermal stress due to the temperature distribution is extremely small, and at the same time the cell width is Since the structure is narrow and easily radiates heat, no hot spot is generated, and the cell is not deteriorated by the hot spot.

(7) The cell of the present invention can be applied to both internal reforming and external reforming.
In the case of external reforming, it is necessary to increase the gas supply amount to the cathode, but by adding a spacer made of an electronically conductive material to the cathode gas passage, it is easy without changing the shape of the cell part. The cathode gas passage can be enlarged.

The basic contents of the present invention have been described with reference to the drawings from the viewpoint of [Means for Solving the Problems], but here, they have not been described so far from the viewpoint of [Embodiments of the Invention]. The technical details that explain the background and the background of the invention will be described.

(1) As shown in FIG. 10, the cell of the present invention basically supplies fuel to the anode electrode 39 by flowing a fuel gas through a closed space of a flat plate tube formed by the anode current collector plate 44 and the electrolyte plate 38. Many gases provided on the cathode current collector are supplied by supplying a gas and flowing an oxidant gas containing oxygen and CO ₂ outside the flat tube-shaped cell constituted by the anode current collector 44 and the cathode current collector 31. An oxidant gas is supplied to the cathode electrode 37 through a small hole, and an electromotive force is generated between both the anode 39 and the cathode 37 disposed with the electrolyte 38 interposed therebetween. In the case of this type of cell, the structure of a header that supplies fuel gas to each cell in a stack in which a plurality of cells are stacked is a very important point.
In the present invention, the cell has a vertically long rectangular thin box shape. However, as shown in FIG. 10, there are fuel supply openings 47 on both upper sides of the thin side surface of the anode current collector. And has openings 47A for anode exhaust on both sides of the lower portion of the side surface.

(2) The cell of the present invention has an effective electrode area other than the peripheral seal portion, and is characterized by a large proportion of the effective electrode area in the total cell area. The square of the effective electrode area is maximized, but on the other hand, in order to allow the fuel gas and the oxidant gas to flow uniformly over the effective electrode area, it is preferable that the flow direction is long and the width direction is narrow. In the present invention, in order to achieve both of these objects, the actual cell shape is a vertically long rectangle, but the ratio (L / D) of the length (L) to the width (D) is reduced, while the fuel is By providing two supply ports and two anode exhaust ports in one cell, the ratio of the length (L) to the width (D) (L / D) is substantially increased, so that the entire effective electrode area is fueled. The gas and the oxidant gas are allowed to flow uniformly, and the economy is satisfied.

(3) As described above, the stack is arranged vertically in the vertical direction, but the fuel gas is supplied from above, and the anode exhaust is discharged at the bottom. A catalytic combustion chamber is disposed immediately below the stack for burning combustible components in the anode exhaust, and a mixing chamber for air and anode exhaust is further provided immediately below the combustion chamber. Air is supplied to the mixing chamber from the lower part of the mixing chamber through a flat plate air preheater 66 provided outside the heat insulating material arranged so as to surround the outside of the stack.
Combustion gas exiting the catalyst combustion chamber flows from the bottom to the top between the cathode current collector plate and the anode current collector plate, and there are a large number of protrusions provided in the anode electrode of the anode current collector plate and the storage portion of the fuel gas passage. Cathode gas is supplied to the cathode electrode through a large number of openings provided in the cathode current collector, serving as a spacer for forming the cathode gas passage.
That is, the fuel gas becomes a counter flow that flows from top to bottom and the oxidant gas flows from bottom to top.
On the other hand, in the power generation reaction, carbonate ions (CO ₃ ²⁻ ) are generated by the reaction of CO ₂ + 1 / 2O ₂ + 2e ⁻ = CO ₃ ^{2− at} the cathode, and the carbonate ions move through the electrolyte to the anode, where CO ₃ ^{2 _{- + H 2 = CO 2 +}} H 2 O + 2e - and the reaction releases electrons in the electrons return to the cathode again through an external circuit. When this reaction continues, an electron flow, that is, an electric current occurs, but this reaction is an overall hydrogen combustion reaction and an exothermic reaction, so that both the anode gas and the cathode gas generally have an outlet temperature higher than the inlet temperature. Is higher.
In the present invention, the flow of the anode gas and the cathode gas is counterflow, so they cancel each other out by heat transfer in the cell, the temperature of the whole cell becomes the most uniform, and thermal stress due to the temperature difference is less likely to occur, Stack damage due to thermal stress is unlikely to occur.

(4) Also, heat is generated inside the cell due to a power generation reaction, and the temperature is generally high in the central portion and the temperature in the peripheral portion is low due to the relationship between the heat generation and the temperature drop due to heat transfer. However, since the cell of the present invention has a narrow width and a long shape, it is difficult to form a hot spot in the center due to heat transfer in the lateral direction, and the cell is caused by the generation of thermal stress due to the hot spot or the high temperature itself. The structure is less susceptible to damage. From this point of view, it is effective to narrow the width and lengthen the length.
4 to 10 do not necessarily have a large aspect ratio, but the aspect ratio is substantially large because two fuel supply ports to the anode and two anode exhaust ports are attached to each cell. In addition, the figure is an example until it becomes tired, and it is an object of the present invention to make a vertically long cell.

(5) As already described, in the present invention, the size of the anode electrode is made larger than that of the cathode electrode so that the position of the peripheral portion of the anode electrode does not coincide with the peripheral portion of the cathode electrode. The structure is such that the peripheral part comes outside the periphery of the cathode storage part of the cathode current collector plate, that is, the peripheral part is overlapped with the peripheral part of the cathode current collector plate. This is because if the edges of both the cathode electrode and the anode electrode coincide with each other, shear stress is likely to be applied to that portion of the electrolyte plate, and the possibility of cracks in the electrolyte plate increases.
Therefore, the soundness of the electrolyte plate was improved by shifting the positions of the edges of the anode electrode and the cathode electrode.

(6) FIG. 13 shows the overall layout of the fuel cell power generation facility of the present invention. A combustion catalyst 71 is disposed immediately above the stack 65, and in the unlikely event that fuel gas leaks from the stack, it is oxidized immediately, thereby ensuring the safety of the equipment. In addition, an activation burner 72 is disposed immediately above. When the fuel is flowed here and ignited by the burner ignition device, the combustion gas is continuously supplied through the surrounding air preheater, and the device can be preheated by natural circulation. A fuel superheater 73 is disposed on the startup burner, a pre-reformer 74 is disposed thereon, and a fuel preheater 75 is disposed thereon. A steam superheater 76 and a mixer 77 are disposed above the fuel preheater, and a steam generator 78 is disposed at the top. By igniting the start-up burner, they can enter an operating state, mix steam and fuel, and supply pre-reformed fuel to the stack.
79 represents an air blower, 80 represents a water supply pump, 81 represents a filter silencer, 82 represents an inverter, 83 represents a gas cylinder, 84 represents a blow tank, 85 represents a control device, 86 represents a brackish water separator, and 87 represents a water supply tank. Since it is not the main part of the present invention, the description is omitted.

(1) FIG. 14 is a sectional view of a cell showing the basic form of the cell of the present invention and various embodiments.
[A] is a basic form of the cell of the present invention corresponding to claim 1, and in the [means for solving the problems], the anode current collector plate 88 is different from the fuel cell described with reference to FIGS. Only. The anode current collector plate is different from the above description in that the anode electrode and the ceiling portion of the fuel gas passage housing 46 are flat. When a plurality of cells of this type are stacked and used as a stack, a conductive spacer is required to form a cathode gas passage between the stacked cells.

[B] is the fuel cell itself described with reference to FIGS. 4 to 10 in [Means for Solving the Problems], and corresponds to claim 2. In this case, a large number of upward protruding portions 46A are provided on the anode electrode of the anode current collector plate 44 and the ceiling portion of the fuel gas passage 46. When a plurality of cells are stacked to form a stack, these protruding portions It serves as a spacer for forming a gas passage.

[C] corresponds to claim 4 and only the cathode current collector 89 is different from the basic shape. The cathode current collector plate has a bridge screen at the bottom surface of the cathode electrode storage portion, and has a number of downwardly projecting bridge portions 90. This portion serves as a spacer for the cathode gas passage, and at the same time, the cathode gas. It is also an opening for. (Fig. 8 [A] is an image of the bridge screen)

[D] is a case where the reforming catalyst 51 is filled inside the protrusion 46A of the anode current collector plate of [B] and corresponds to claim 3.

[E] replaces the bridge screen type fuel gas passage of the fuel cell of [D] with a fuel gas passage 91 of a metal foam body, and corresponds to claim 6.

Although the five examples have been described with reference to FIG. 14, (2) or (3) is a basic embodiment, and there are various applications and combinations. The best combination depends on the required conditions. Determined. However, what has been described so far is basically the best embodiment [means for solving the problems].

Since the fuel cell is an energy conversion device that directly converts the chemical energy of the fuel gas into electric energy, it can be basically applied to any field as a DC or AC power generation facility or power source. On the other hand, since the present invention mainly focuses on the improvement of molten carbonate fuel cells, it is suitable for stationary power generation facilities when considered as a high temperature fuel cell. In addition, high-temperature fuel cells are suitable for cogeneration because exhaust heat becomes high, and are suitable for industrial and household cogeneration.

Explanatory drawing of components of conventional cell [A] Bird's eye view [B] Side view Explanatory drawing concerning conventional gas supply method of cell [A] Internal manifold type [B] External manifold type Conceptual diagram of conventional stack Structural diagram of cathode current collector of the present invention Structural diagram of cathode electrode of the present invention Structure diagram of electrolyte plate of the present invention Structure diagram of anode electrode of the present invention Structure of fuel gas passage of the present invention Structural diagram of anode current collector of the present invention [A] Cell assembly sectional view [B] Fuel supply and exhaust header structure diagram Assembly sectional view of the stack of the present invention Assembly sectional view and gas flow around the stack of the present invention Layout of fuel cell power generation facility of the present invention Various embodiments of the cell of the invention

Explanation of symbols

1. 1. Electrolyte plate 2. Anode electrode 3. Cathode electrode Cathode gas passage (corrugated plate)
5. Anode gas passage (corrugated plate)
6). Center plate 7. Mask plate8. Cathode current collector 9. Anode current collector 10. 10. Effective electrode part of internal manifold type separator Resistance part of internal manifold type separator 12. 12. Cathode gas inlet of internal manifold type separator 13. Cathode gas outlet of internal manifold type separator Anode gas inlet of internal manifold separator 15. Anode gas outlet of internal manifold separator 16. 16. Seal part of internal manifold type separator Effective electrode part of external manifold type separator 18. Resistance part of external manifold type separator 19. Seal part of external manifold type separator 20. Cathode gas inlet header of external manifold separator 21. Cathode gas outlet header of external manifold separator 22. Anode gas inlet header of external manifold separator 23. Anode gas outlet header of external manifold type separator 24. Cell stack part of conventional stack 25. Conventional stack header cover 26. Insulation / insulation material of conventional stack 27. Conventional stack clamping device 28. Conventional stack tension rod 29. Conventional stack tightening spring 30. Extracting current from a conventional stack 31. Cathode current collector of the present invention 32. Cathode electrode storage portion 33 of the cathode current collector of the present invention. The trapezoidal part (seal part) of the cathode current collector of the present invention
34. A small hole 35 provided in the cathode electrode housing portion of the cathode current collector of the present invention; The outer wall of the trapezoidal portion of the cathode current collector plate of the present invention 36. A notch 37 provided on the short side of the outer wall of the trapezoidal portion of the cathode current collector plate of the present invention 37. Cathode electrode 38 of the present invention. Electrolyte plate of the present invention 39. Anode electrode 40 of the present invention. Cutout portions 41 of each corner of the anode electrode of the present invention. Fuel gas passage 42 of the present invention 42. Bridge portion shape 42A. Of the bridge screen of the fuel gas passage of the present invention. Bridge part (convex part) of bridge screen of fuel gas passage of the present invention
43. Notch 44 of each corner of fuel gas passage of the present invention 44. Anode collector plate 45 of the present invention 45. The base part (seal part) of the anode current collector of the present invention
46. The anode electrode and fuel gas passage housing 46A. Projection 47 provided on the anode current collector of the present invention 47. The fuel supply port 47A. An anode exhaust port provided in the anode current collector of the present invention 48. Electrolyte support component of the present invention 49. The outer wall 50 of the trapezoidal portion of the anode current collector of the present invention 50. 51. Notch 51 provided on the outer wall of the trapezoidal portion of the anode current collector of the present invention 52. Reforming catalyst of the present invention Insulation and sealing material of the present invention 53. Fuel supply header 54. of the present invention. The fuel supply header opening 55 of the present invention 55. Anode exhaust header 56 of the present invention Cell stack portion 57 of the stack of the present invention 57. Current extraction plate 58 of the stack of the present invention 58. Heat insulation / insulation material of stack of the present invention 59. Stack tightening device 60. A spring for tightening the stack of the present invention 61. Cover of the stack clamping spring of the present invention 62. Tension rod for tightening the stack of the present invention 63. Current extraction cable 64. of the stack of the invention. Inverter 65 of the present invention. 56. Stack arrangement of the present invention and gas flow therein. Air preheater 67 of the present invention 67. Insulation material 68 of the present invention 68. The anode exhaust and air mixing chamber of the present invention 69. Combustion chamber 70 of the present invention. Combustion catalyst of the present invention 71. Combustion catalyst of the present invention 72. Activation burner 73 of the present invention 73. Fuel superheater 74. Pre-reformer of the present invention 75. Fuel preheater 76 of the present invention 76. Steam superheater of the present invention 77. Mixer of the present invention 78. Steam generator of the present invention 79. Air blower 80. of the present invention. Water supply pump of the present invention 81. Filter silencer 82. of the present invention. Inverter 83 of the present invention. The cylinder storage place of the present invention 84. Blow tank 85. of the present invention. Control device 86 of the present invention. Brackish water separator 87 of the present invention 87. Water supply tank 88. of the present invention. Anode current collector of the present invention 89. Cathode current collector 90 of the present invention 90. Projection part 91 of the cathode current collector plate of the present invention 91. Metal foam AIR of the present invention Air FG Fuel gas

Claims (12)

  A rectangular plate-shaped flat plate is formed with a narrow and narrow base, and a large number of small holes are formed on the inner bottom of the base. The height of the base is the cathode. The thickness of the electrode is approximately equal to the thickness of the electrode, and the inner shape of the trapezoid is slightly larger than the rectangular flat cathode electrode. A rectangular flat plate that has the same shape as the cathode flat plate, and has the same area as the projected area of the cathode current collector, and has insulation, ionic conductivity, and airtightness. The electrolyte plate is placed so as to cover the entire surface of the cathode electrode, and each peripheral portion of the electrolyte plate is in contact with each peripheral plate-like portion of the cathode current collector plate so as to ensure a wet seal function by the liquid electrolyte. Above, the area is larger than the cathode electrode, A rectangular and flat anode electrode having an area smaller than that of the plate and having electronic conductivity and air permeability is arranged so that each peripheral portion thereof is outside the cathode electrode housing portion of the cathode current collector plate, and the anode is placed thereon. A metallic fuel gas passage having almost the same area as the electrode is placed, and further, a rectangular thin plate is formed on each of the peripheral parts, and a narrow base part is formed on the inner side of the base part. The shape of the ceiling is flat, the shape is a rectangular flat plate, the area is slightly larger than the anode electrode and the fuel gas passage, and the height of the platform is the height of the anode electrode and the fuel gas passage overlapped An anode current collector plate having a portion where the height of the trapezoidal portion for supplying and discharging the fuel gas is low at both end portions on the long side of the trapezoidal portion. Wet seal with liquid electrolyte in contact with electrolyte plate The fuel gas is supplied to the anode electrode through the fuel gas passage from the fuel supply portion of the anode current collector plate of the fuel cell formed as described above, and the cathode is provided outside the cathode current collector plate. A fuel cell, wherein a gas is supplied and cathode gas is supplied to the cathode electrode through a large number of small holes provided in the cathode current collector.   In a stack in which a large number of independent upward projections are formed on the ceiling of the anode electrode of the anode current collector plate and the fuel gas passage, and a plurality of cells are stacked, this projection serves as a spacer for the cathode gas passage. 2. The fuel cell according to claim 1, wherein   3. The fuel cell according to claim 2, wherein a reforming catalyst is filled inside a large number of independent upward projections provided on the ceiling of the anode electrode of the anode current collecting plate and the fuel gas passage.   The cathode current collector plate has a bottom surface of the cathode storage portion formed as a convex bridge screen, and an opening for the cathode gas passage is formed. At the same time, in the stack in which the plurality of cells are stacked, the cathode gas passage The fuel cell according to claim 1, wherein the spacer is a spacer.   5. The fuel cell according to claim 1, wherein a bridge screen is used as the fuel gas passage.   5. The fuel cell according to claim 1, wherein a metal foam is used as the fuel gas passage.   7. The fuel cell according to claim 1, wherein supporting members for the electrolyte plate are disposed at the fuel supply port and the anode exhaust port of the anode current collector plate.   A fuel cell stack in which a plurality of flat plate fuel cells according to claim 1 are arranged in a direction perpendicular to the ground, and is integrated with a fastening device from the front and rear, and a fuel supply port to the anode is at the top, The anode exhaust port is arranged at the bottom, and a catalytic combustion chamber is provided immediately below the stack, and further, an anode exhaust and air mixing chamber is provided immediately below the stack, and the anode exhaust has a passage leading to the mixing chamber. On the other hand, a plate-shaped air preheater is arranged so as to surround the four side surfaces of the stack, air is supplied from the upper part, and the preheated air discharged from the lower part is led to the mixing chamber, where the anode After mixing with the exhaust, it is led to the catalyst combustion chamber, where it comes into contact with the combustion catalyst and combustible components in the anode exhaust are combusted, and the high-temperature combustion gas passes through the outside of the cathode current collector plate from the bottom of the stack. Down In the process, oxygen and carbon dioxide are supplied from the opening of the cathode current collector plate to the cathode, so that the flow of fuel gas in the anode and the flow of combustion gas in the cathode A fuel cell power generator.   The stack composed of a plurality of fuel cells according to claims 1 to 7, wherein the fuel supply port and the anode exhaust port are on two side surfaces of the stack, but all the fuel supply ports or anode exhaust ports on each side surface are A fuel cell characterized in that it is covered with a single flat sealing material each having an insulating property, an opening corresponding to each fuel supply port is provided in the sealing material, and a metal fuel gas header is provided thereon. stack.   8. The fuel cell according to claim 1, wherein a plurality of notches are provided on a short side of the outer wall surface of the base portion of the cathode current collector plate to form a cathode gas passage.   8. The fuel cell according to claim 1, wherein a plurality of notches are provided on the short side of the outer wall surface of the base portion of the anode current collector plate to form a cathode gas passage.   8. The fuel cell according to claim 1, wherein at least a part of the outer wall surface of the base part of the anode current collector plate and the outer wall surface of the base part of the cathode current collector plate are joined. Fuel cell stack.

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