JP5098134B2 - Solid oxide fuel cell - Google Patents

Description

  The present invention relates to a solid oxide fuel cell in which a solid oxide fuel cell stack is stored in a storage container.

  Conventionally, a battery module surrounding a battery module that includes a battery stack that generates power from a fuel gas and an oxygen-containing gas, and a combustion section that causes the remaining fuel gas and the oxygen-containing gas from the battery stack to contact and burn There has been proposed a fuel cell provided with a heat recovery passage for recovering heat loss from (see Patent Document 1).

In the solid oxide fuel cell described in Patent Document 1, a cell stack composed of a plurality of fuel cells is accommodated in a storage container having a pipe between a frame and a heat insulating material, and is passed through a fuel gas supply pipe. The fuel gas is supplied, and the oxygen-containing gas pipe and the oxygen-containing gas are supplied through the pipe.
JP 2003-249256 A

  Since solid oxide fuel cells operate at a high temperature of about 700-1000 ° C, the temperature of the battery stack that generates power is properly maintained, heat loss is prevented, power is generated with high efficiency, and the outer surface is allowed. In order to keep the temperature below a certain temperature, it is necessary to cover the battery module containing the battery stack with a thick heat insulating material, which hinders the compactness of the battery module including the surrounding heat insulating layer.

  In addition, since the heat recovery heat exchanger that recovers heat from the combustion exhaust gas and the power generation module are arranged side by side and surrounded by the heat recovery passage, sufficient compactness cannot be achieved and the heat radiation area of the high-temperature part increases. It was.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a solid oxide fuel cell capable of achieving sufficient compactness and achieving effective heat recovery.

Solid oxide fuel cell according to claim 1, containing the combustion unit for combusting contacting the residual fuel gas and oxygen-containing gas from the cell stack and the cell stack for generating electricity from a fuel gas and an oxygen-containing gas have a contained space, the upper surface, around the power generation module having a lower surface and side surfaces, in the solid oxide fuel cell having a heat recovery passage for recovering the lost heat of the power module, and the heat recovery passage and the power generation module during comprises a one or more layers of heat recovery heat exchanger which surrounds the battery module, and a passing path, the heat recovery heat exchanger, flowing the exhaust gas from the power generation module being connected to said enclosed space a first flow path, performs heat exchange between said oxygen-containing gas and the flue gas and a second flow passage connected to said enclosed space flowing the oxygen-containing gas, the first The said the road second flow passage surrounds the side surface of the power generation module, the heat recovery path passes through the inside thereof said oxygen-containing gas, the heat recovery heat exchanger in the opposite side to the enclosed space Connected to the second flow path to surround the heat recovery heat exchanger, and the passage is connected to the first flow path of the heat recovery heat exchanger on the side opposite to the internal space, and the heat recovery It extends in a different direction from the heat recovery passage without surrounding the heat exchanger .

  In this case, the temperature gradient can be made gradual, and as a result, effective heat recovery can be achieved, and furthermore, the overall compactness can be achieved by eliminating the need for thick heat insulating materials. it can.

  The solid oxide fuel cell according to claim 2 further includes a heat insulation layer between at least one of the power generation module and the heat recovery heat exchanger and between the heat recovery heat exchanger and the heat recovery passage.

  In this case, more effective heat recovery can be achieved.

  The solid oxide fuel cell according to claim 3 employs a counter-flow heat exchanger as the heat recovery heat exchanger.

In this case, more effective heat recovery can be achieved.
The solid oxide fuel cell according to claim 4 employs a structure in which the first flow path and the second flow path of the heat recovery heat exchanger spirally surround the power generation module.

  In this case, the heat recovery structure can be simplified.

  The solid oxide fuel cell according to claim 5 employs a structure having a structure surrounding a power generation module in a spiral shape as the heat recovery passage.

  In this case, the heat recovery structure can be simplified.

  The solid oxide fuel cell according to claim 6 employs, as the heat recovery heat exchanger, one having a structure surrounding a power generation module concentrically.

  In this case, the heat recovery structure can be simplified.

  The solid oxide fuel cell according to claim 7 employs a structure having a concentrically surrounding power generation module as the heat recovery passage.

  In this case, the heat recovery structure can be simplified.

  The solid oxide fuel cell according to claim 8 includes two or more heat recovery heat exchangers, and a heat insulating layer is provided between the layers of the heat recovery heat exchanger.

  In this case, the temperature gradient can be further moderated, and as a result, effective heat recovery can be achieved.

  In this case, more effective heat recovery can be achieved.

In the solid oxide fuel cell according to claim 9, the heat recovery passage and the second flow path of the heat recovery heat exchanger are formed as an integral passage.

  In this case, more effective heat recovery can be achieved.

The solid oxide fuel cell according to claim 10 further includes a second heat recovery passage for performing heat recovery by the fuel gas or the oxygen-containing gas supplied to the cell stack on the upper surface side or the lower surface side of the power generation module. .

  In this case, more effective heat recovery can be achieved.

The solid oxide fuel cell according to claim 11 further includes an exhaust gas guide path for guiding the exhaust gas from the heat recovery heat exchanger to a water vaporizer for fuel reforming.

  In this case, the heat energy of the exhaust gas from the heat recovery heat exchanger can be used effectively.

The solid oxide fuel cell according to claim 12 branches the oxygen-containing gas to the cell stack, and supplies a part of the gas to the cell stack via the heat recovery passage (4) and the heat recovery heat exchanger, It further includes a branch flow rate adjusting means for supplying the remaining part to the battery stack by bypassing the heat recovery passage and the heat recovery exchanger .

  In this case, effective heat recovery can be achieved by adjusting the branching amount of the oxygen-containing gas.

The solid oxide fuel cell according to claim 13 is configured such that the solid fuel cell stack is a stack in which flat plate fuel cells are stacked, and a fuel gas after power generation and a gas containing an oxidant after power generation on the outer periphery of the stack. A heat recovery heat exchanger having a combustion chamber for mixing and burning and recovering heat from the exhaust gas is arranged so as to surround the combustion chamber.

  In this case, by placing a high-temperature combustor on the outer periphery, temperature unevenness in the stacking direction of the fuel cell can be prevented, and heat can be efficiently recovered in the adjacent heat recovery heat exchanger. .

  The invention according to claim 1 can achieve effective heat recovery, and also has a specific effect that it is possible to achieve compactness as a whole without using a thick heat insulating material.

  The invention of claim 2 has a specific effect that more effective heat recovery can be achieved.

  The invention of claim 3 has a specific effect that more effective heat recovery can be achieved.

  The invention of claim 4 has a specific effect that the heat recovery structure can be simplified.

  The invention of claim 5 has a specific effect that the heat recovery structure can be simplified.

  The invention according to claim 6 has a specific effect that the heat recovery structure can be simplified.

  The invention according to claim 7 has a specific effect that the heat recovery structure can be simplified.

  The invention according to claim 8 has a specific effect that effective heat recovery can be achieved.

The invention according to claim 9 has a specific effect that more effective heat recovery can be achieved.

The invention according to claim 10 has a specific effect that more effective heat recovery can be achieved.

The invention of claim 11 has a specific effect that the thermal energy of the exhaust gas from the heat recovery heat exchanger can be used effectively.

The invention of claim 12 has a specific effect that effective heat recovery can be achieved.

In the invention of claim 13 , by placing a high-temperature combustion chamber on the outer periphery, temperature unevenness in the stacking direction of the fuel cell can be prevented and heat is efficiently recovered by the adjacent heat recovery heat exchanger. There is a unique effect of being able to.

  Embodiments of a solid oxide fuel cell according to the present invention will be described below in detail with reference to the accompanying drawings.

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

  The solid oxide fuel cell includes a fuel cell stack 1, a storage container 2 that stores the fuel cell stack 1, a heat recovery heat exchanger 3 that surrounds the storage container 2, and a heat recovery heat exchanger 3. A heat recovery passage 4 that reforms the fuel gas, a power generation module, a heat recovery heat exchanger 3, and a heat insulating material 6 that surrounds the heat recovery passage 4.

The fuel cell stack 1 and the storage container 2 constitute a power generation module.
In addition, the reformer 5 is disposed inside the storage container 2 so that fuel gas is supplied to the fuel cell stack 1 through the reformer 5.

A part of the oxygen-containing gas (for example, air) passes through the heat recovery passage 4 and the heat recovery heat exchanger 3 in this order, and the remainder is supplied directly to the fuel cell stack 1.
Combustion gas (exhaust gas) discharged from the power generation module is discharged to the outside through the heat recovery heat exchanger 3.

  The operation of the solid oxide fuel cell configured as described above is as follows.

  By supplying the oxygen-containing gas and the fuel gas reformed by the reformer 5 to the fuel cell stack 1, power generation is performed and the remaining fuel gas is burned, and the exhaust gas passes through the heat recovery heat exchanger 3. To discharge outside.

  Since this exhaust gas is heat-exchanged with the oxygen-containing gas while passing through the heat recovery heat exchanger 3, the temperature gradually decreases and is finally discharged to the outside. On the contrary, a part of the oxygen-containing gas recovers the heat flowing out from the heat recovery heat exchanger 3 by heat conduction or the like while passing through the heat recovery passage 4, and then heats up. While passing through the exchanger 3, the temperature is further increased by exchanging heat with the exhaust gas having a higher temperature. Then, the oxygen-containing gas that has reached a high temperature is supplied to the fuel cell stack 1.

  In addition, since the point which maintains the operating temperature of about 700-1000 degreeC and continues combustion of fuel gas is conventionally well-known, detailed description is abbreviate | omitted here.

  In this embodiment, the temperature of the exhaust gas is lowered by the heat recovery heat exchanger 3 and the amount of heat flowing out to the outside is recovered by the oxygen-containing gas passing through the heat recovery passage 4, so that the thickness of the heat insulating material 6 is greatly increased. The overall size can be greatly reduced.

  Further explanation will be given.

  2 is a schematic diagram showing a state in which the heat recovery heat exchanger 3 and the heat recovery passage 4 are provided and the heat insulating material 6 is not provided, and FIG. 3 shows the heat recovery heat exchanger 3 and the heat recovery passage 4. It is the schematic which shows the state which provided the heat insulating material.

  The heat recovery heat exchanger 3 has a function of recovering heat loss from the power generation module to the surroundings in addition to heat recovery from the exhaust gas, and the heat recovery passage 4 has a function of recovering heat loss from the inner heat recovery heat exchanger to the surroundings. Each has a function to collect.

  And by providing a heat insulation layer between each layer, since the outflow amount (heat loss) of the outward heat from the power generation module can be reduced, the heat recovery between the heat recovery heat exchanger 3 and the heat recovery passage 4 The load is reduced, and the heat recovery heat exchanger 3 and the heat recovery passage 4 can be shortened. As a result, the number of layers of the heat recovery heat exchanger 3 and the heat recovery passage 4 can be reduced, the thickness of the heat recovery structure as a whole can be reduced, and the solid oxide fuel cell including the heat insulation heat recovery structure can be reduced. Compactness can be achieved.

  Moreover, since the flow path length can be shortened, the blowing power can also be reduced.

FIG. 4 is a schematic view showing a fuel cell system including the solid oxide fuel cell of FIG.
This system includes a fuel gas supply source 7, a desulfurizer 8 that receives a fuel gas and performs a desulfurization process, and outputs (desulfurized fuel gas) from the desulfurizer 8 to the solid oxide fuel cell of FIG. A vaporizer 10 that vaporizes the desulfurized fuel gas to which water is added by performing heat exchange between the water addition unit 9 that adds water and the exhaust gas discharged from the heat recovery heat exchanger 3, and an air supply source 11 And a branch flow rate adjusting unit 12 that supplies a part of the air to the heat recovery passage 4, supplies the remaining air directly to the fuel cell stack 1, and adjusts the amount of both the supplied air. .

  In this system, since the flow rate of the branched air can be adjusted by the branch flow rate adjusting unit 12, the flow rate of the branched air according to the operation state such as during rated operation, partial load operation, standby operation, etc. An appropriate amount can be obtained, and good high-efficiency operation can be realized regardless of the operation state.

  The heat recovery heat exchanger 3 is formed by integrally arranging an exhaust gas channel 3a through which exhaust gas flows and an oxygen-containing gas channel 3b through which oxygen-containing gas flows in a good heat exchange state. As shown in FIG. 6, it may be configured in a spiral shape, but as shown in FIG. 6, it may be configured in a concentric shape. However, in the case where importance is attached to simplification of the configuration, the configuration of FIG. 5 is adopted. It is preferable to do. This is because the communication path 3c that connects the inner layer and the outer layer is required in the case of the concentric configuration, whereas the communication path 3c is not required in the case of the spiral configuration.

  FIG. 7 is a schematic view showing another embodiment of the solid oxide fuel cell of the present invention.

  This solid oxide fuel cell is different from the solid oxide fuel cell of FIG. 1 only in that heat recovery passages 14 are provided above and below the power generation module.

  However, this heat recovery passage 14 may recover heat with fuel gas, but may recover heat with oxygen-containing gas.

  The heat recovery passage 14 is preferably provided above and below the power generation module, but can be provided only in one of them.

  FIG. 8 is a schematic view showing still another embodiment of the solid oxide fuel cell of the present invention.

  In this solid oxide fuel cell, a heat recovery passage 4 is arranged on the outer peripheral surface of the fuel cell stack 1 (one surface in the case of a cylindrical shape, and four surfaces in the case of a quadrangular prism), and the lower surface of the fuel cell stack 1 is disposed. A recirculation fuel gas heat recovery heat exchanger 18 and a recirculation fuel gas cooler 19 are arranged in this order, and a combustor 20, a heat recovery heat exchanger 3, and a heat recovery passage 14 are arranged in this order on the upper surface of the fuel cell stack 1. It is arranged.

  In this case, the high temperature part of the fuel cell stack and the combustor is centered on the module, the surroundings are the combustion gas heat recovery heat exchanger, the recirculation gas heat recovery heat exchanger, the outermost layer is the heat recovery passage and the recirculation fuel gas By disposing the elements with lower temperatures in the order of the cooler, the heat dissipation loss can be reduced as much as possible.

  FIG. 9 is a schematic view showing still another embodiment of the solid oxide fuel cell of the present invention.

  This solid oxide fuel cell has a combustion chamber 22, a heat recovery heat exchanger 3, and a heat recovery passage 4 on the outer peripheral surface of the fuel cell stack 1 (one surface in the case of a cylindrical shape, and four surfaces in the case of a square pillar shape). Are arranged in this order, and the recirculation fuel gas heat recovery heat exchanger 18 and the recirculation fuel gas cooler 19 are arranged in this order on the lower surface of the fuel cell stack 1, the combustion chamber 22, and the heat recovery heat exchanger 3. A heat recovery passage 14 is disposed on the upper surface of the battery stack 1, the combustion chamber 22, and the heat recovery heat exchanger 3.

  In this case, by placing a high-temperature combustor on the outer periphery, temperature unevenness in the stacking direction of the fuel cell can be prevented, and heat can be efficiently recovered by the adjacent combustion gas heat recovery device. .

  FIG. 10 is a schematic view showing still another embodiment of the solid oxide fuel cell of the present invention.

  The solid oxide fuel cell is different from the solid oxide fuel cell of FIG. 9 in that the upper end of the heat recovery passage 4 disposed on the outer peripheral surface of the fuel cell stack 1 via the combustion chamber 22 and the heat recovery heat exchanger 3. It is only the point which shortened the part and lower end part by the thickness of the heat recovery channel | path 14 of the uppermost part, and the thickness of the recirculation fuel gas cooler 19. FIG.

  In this case, the height of the heat recovery passage 4 disposed on the outer peripheral surface of the fuel cell stack 1 via the combustion chamber 22 and the heat recovery heat exchanger 3 can be shortened, and a high-temperature combustor can be installed. By placing it on the outer periphery, temperature unevenness in the stacking direction of the fuel cells can be prevented, and heat can be efficiently recovered in the adjacent combustion gas heat recovery device.

It is the schematic which shows one Embodiment of the solid oxide fuel cell of this invention. It is the schematic which shows the state which provided the heat recovery heat exchanger and the heat recovery channel | path, and has not provided the heat insulating material. It is the schematic which shows the state which provided the heat recovery heat exchanger, the heat recovery channel | path, and the heat insulating material. It is the schematic which shows the fuel cell system containing the solid oxide fuel cell of FIG. It is a schematic perspective view which shows an example of a structure of a heat recovery heat exchanger and a heat recovery channel. It is a schematic longitudinal cross-sectional view which shows the other example of a structure of a heat recovery heat exchanger and a heat recovery channel | path. It is the schematic which shows other embodiment of the solid oxide fuel cell of this invention. It is the schematic which shows other embodiment of the solid oxide fuel cell of this invention. It is the schematic which shows other embodiment of the solid oxide fuel cell of this invention. It is the schematic which shows other embodiment of the solid oxide fuel cell of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell stack 3 Heat recovery heat exchanger 4 Heat recovery passage 6 Heat insulating material 10 Vaporizer 12 Branch flow rate adjustment part

Claims (13)

Fuel gas and oxygen-containing cell stack (1) for generating electric power from the gas and the remainder of the fuel gas and the oxygen-containing gas is contacted from the cell stack (1) have a containing space for containing a combustion unit for combusting In the solid oxide fuel cell having the heat recovery passage (4) for recovering the heat loss from the power generation module around the power generation module having the upper surface, the lower surface and the side surface,
Wherein between the the power generation module heat recovery passage (4), wherein the one or more layers of heat recovery heat exchanger surrounding the power generation module (3), and a through passage,
The heat recovery heat exchanger, said a first flow path for flowing the exhaust gas from the power generation module being connected to said enclosed space, and a second flow path for flowing the oxygen-containing gas and the exhaust gas having an oxygen Heat exchange with the contained gas, the first flow path and the second flow path surround the side surface of the power generation module,
The heat recovery passage is surrounded by the oxygen-containing gas and connected to the second flow path of the heat recovery heat exchanger on the opposite side of the internal space to surround the heat recovery heat exchanger. ,
The passage is connected to the first flow path of the heat recovery heat exchanger on the opposite side to the internal space, and extends in a direction different from the heat recovery passage without surrounding the heat recovery heat exchanger. A solid oxide fuel cell.   The heat insulation layer is further included in at least one between the power generation module and the heat recovery heat exchanger (3) and between the heat recovery heat exchanger (3) and the heat recovery passage (4). The solid oxide fuel cell as described.   The solid oxide fuel cell according to claim 1 or 2, wherein the heat recovery heat exchanger (3) is a counterflow heat exchanger. 4. The solid oxide fuel cell according to claim 1, wherein the first flow path and the second flow path of the heat recovery heat exchanger (3) have a structure surrounding the power generation module in a spiral shape. 5.   4. The solid oxide fuel cell according to claim 1, wherein the heat recovery passage has a structure surrounding the power generation module in a spiral shape. 5.   4. The solid oxide fuel cell according to claim 1, wherein the heat recovery heat exchanger has a structure that concentrically surrounds the power generation module. 5.   4. The solid oxide fuel cell according to claim 1, wherein the heat recovery passage has a structure that concentrically surrounds the power generation module. 5.   The solid oxide fuel cell according to any one of claims 1 to 7, further comprising a heat recovery heat exchanger having two or more layers, wherein a heat insulating layer is provided between the layers of the heat recovery heat exchanger. The solid electrolyte according to any one of claims 1 to 8, wherein the heat recovery passage (4) and the second flow path (3b) of the heat recovery heat exchanger (3) are continuous and integral passages. Type fuel cell.   10. The semiconductor device according to claim 1, further comprising a second heat recovery passage (14) that performs heat recovery using fuel gas or oxygen-containing gas supplied to the battery stack on the upper surface side or the lower surface side of the power generation module. A solid oxide fuel cell according to claim 1.   The solid oxide fuel according to any one of claims 1 to 10, further comprising an exhaust gas guide path that guides the exhaust gas from the heat recovery heat exchanger (3) to a water vaporizer (10) for fuel reforming. battery.   The oxygen-containing gas to the battery stack (1) is branched, a part thereof is supplied to the battery stack via the heat recovery passage (4) and the heat recovery heat exchanger, and the remaining part is supplied to the heat recovery passage. The solid oxide fuel cell according to any one of claims 1 to 11, further comprising a branch flow rate adjusting means (12) that bypasses the heat recovery exchanger and supplies the battery stack to the battery stack.   The fuel cell stack (1) is composed of a stack in which flat plate fuel cells are stacked, and a combustion chamber (22) that mixes and burns fuel gas after power generation and gas containing oxidant after power generation around the stack. The solid electrolyte according to any one of claims 1 to 12, wherein a heat recovery heat exchanger (3) for recovering heat from the exhaust gas is disposed so as to surround the combustion chamber (22). Type fuel cell.

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