JP2009231211A - Fuel cell module and fuel cell having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell module for restraining consumption of a fuel gas in starting and securing a reducing atmosphere at a fuel electrode side. <P>SOLUTION: The fuel cell module FC includes a plurality of unit-cells 2 for a fuel cell operated by the fuel gas and an oxidizer gas, and a module container 8 for housing the plurality of unit-cells 2 for a fuel cell. A combustion chamber 27 for burning the fuel gas and the oxidizer gas remained after reacted in the plurality of unit-cells 2 for a fuel cell is formed in the module container 8. A fuel reformer is arranged by dividing into a first reformer 41 and a second reformer 42 in a passage 50 wherein an exhaust gas generated in the combustion chamber 27 is guided outside the module container 8, and thermal capacity of the first reformer 41 is smaller than the thermal capacity of the second reformer 42. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell module including a plurality of fuel cells and a fuel cell including the same.

Hydrogen gas is used as a fuel gas for operating the fuel cell. Therefore, in fuel cells, hydrogen gas itself is supplied or hydrogen gas is generated using some means. In view of the current situation where the supply of hydrogen gas is not established as a social infrastructure, it is widely performed to obtain hydrogen gas by steam reforming raw fuel using a catalyst (for example, Patent Document 1 below) reference).
JP 2006-290633 A

  The present inventors have repeatedly investigated whether there is a more effective start-up method in a fuel cell module and a fuel cell including a plurality of fuel cells that are operated by a fuel gas and an oxidant gas. Specifically, the fuel cell module and the fuel cell that can further suppress the consumption of the fuel gas at the time of start-up have been studied. In the above conventional technique, although attention is paid to the start-up time of the fuel cell, there is no mention of fuel gas consumption at the start-up, and the present inventors have tried a completely different approach. In the new approach, the inventors of the present invention, in the fuel cell module, particularly in the fuel cell module used for SOFC (solid oxide fuel cell), at the time of start-up (at the time of temperature rise) or at the time of stop (at the time of temperature drop) It was noted that the gas atmosphere on the fuel electrode side must maintain a reducing atmosphere at a gas atmosphere temperature of 200 ° C. or higher so that the fuel electrode does not oxidize.

  As a method for creating a reducing atmosphere in this way, a method of supplying hydrogen gas (first method), a method of supplying a hydrocarbon-based gas (reformed gas) as a partial oxidation gas using a burner or a partial oxidation catalyst There are three possible methods (second method): a method in which steam is mixed with a hydrocarbon-based gas (reformed gas), reformed with a reforming catalyst, and supplied (third method).

  In the first method, since the infrastructure for supplying hydrogen gas is not generally prepared, a hydrogen gas cylinder or a hydrogen adsorbing material (hydrogen storage alloy or the like) is required. Accordingly, it is inevitable to secure a place for installing the hydrogen gas cylinder and the like, and to manage and replace the internal capacity of the hydrogen gas cylinder. In the second method, since the discharge temperature of the partial oxidation gas becomes a high temperature exceeding 1000 ° C., it is suitable at the time of start-up (temperature rise) but unsuitable at the time of stop (temperature fall). In the third method, the temperature required at the time of reforming is about 500 ° C., which is suitable both at the time of start-up (at the time of temperature increase) and at the time of stop (at the time of temperature decrease).

  Accordingly, an object of the present invention is to provide a fuel cell module capable of suppressing the consumption of fuel gas at the time of startup and ensuring a reducing atmosphere on the fuel electrode side, and a fuel cell including the same. .

  In order to achieve the above object, a fuel cell module according to the present invention includes a plurality of fuel cells operated by fuel gas and an oxidant gas, and a modification for reforming a reformed gas into a fuel gas. A fuel cell module comprising a container and a container for housing the plurality of fuel cells, wherein the container includes residual fuel gas and oxidant gas that have reacted in the plurality of fuel cells. In the flow path through which exhaust gas generated in the combustion section is led to the outside of the container, the reformer includes a first reformer and a second reformer. The heat capacity of the first reformer is smaller than the heat capacity of the second reformer.

  According to the present invention, it is possible to provide a fuel cell module capable of suppressing the consumption of fuel gas at the time of startup and ensuring a reducing atmosphere on the fuel electrode side, and a fuel cell including the fuel cell module.

  Prior to describing the best mode for carrying out the present invention, the function and effect of the present invention will be described.

  A fuel cell module according to the present invention includes a plurality of fuel cells operated by fuel gas and an oxidant gas, a reformer for reforming a gas to be reformed into fuel gas, and the plurality of fuels A fuel cell module including a container for housing battery cells, wherein the container is formed with a combustion portion for burning the remaining fuel gas and oxidant gas reacted in the plurality of fuel battery cells. The reformer is divided into a first reformer and a second reformer in a flow path through which exhaust gas generated in the combustion section is led to the outside of the container. The heat capacity of the first reformer is smaller than the heat capacity of the second reformer.

  In the present invention, the reformed gas is reformed into fuel gas using heat generated in the combustion section that burns the remaining fuel gas and oxidant gas reacted in the plurality of fuel cells, and the fuel We focus on keeping the fuel electrode side in a reducing atmosphere using gas. In that case, if a reformer that satisfies the reforming capability during steady operation is used, the reformer has a large heat capacity at the start of operation, so it is necessary to heat up the fuel electrode by introducing a large amount of fuel gas. Since the amount of fuel gas after reforming required for maintaining is less than the amount of fuel gas after reforming required during steady operation, reforming of an amount of reformed gas more than necessary Will do. This directly consumes more gas to be reformed and consumes more fuel gas than necessary. Therefore, the reformer is divided into two reformers, a first reformer and a second reformer, and the divided first reformer and second reformer are generated in the combustion section. Is arranged in a flow path that leads to the outside of the container, so that heat generated in the combustion section can be used. Furthermore, since the heat capacity of the first reformer is configured to be smaller than the heat capacity of the second reformer, the first reformer is adapted to the amount of fuel gas required at the start of operation. It can be formed, and consumption of fuel gas more than necessary can be avoided.

  In the fuel cell module according to the present invention, it is also preferable that the first reformer is disposed upstream of the second reformer in the flow path.

  According to this preferred embodiment, since the first reformer having a small heat capacity is arranged upstream of the second reformer having a large heat capacity, that is, closer to the combustion section, the combustion heat is second modified. Heat can be effectively applied by the first reformer before feeding to the mass device. Therefore, it becomes possible to more effectively apply heat to the first reformer that has a small heat capacity and easily applies heat to the gas to be reformed that passes through the inside, and the gas to be reformed that passes through the first reformer is reduced. It can be reformed with less fuel gas combustion. As a result, the reducing atmosphere of the fuel electrode of the fuel cell can be maintained by supplying less reformed gas at startup.

  In the fuel cell module according to the present invention, it is preferable that a reformed gas pipe for supplying the gas to be reformed in parallel to the first reformer and the second reformer is provided.

  According to this preferred aspect, since the first reformer and the second reformer having different heat capacities are provided with the reformed gas pipes that can supply the reformed gas in parallel, for example, Depending on the operating conditions of the fuel cell module, the gas to be reformed can be selectively supplied to the reformer having an appropriate reforming capacity, and the gas to be reformed can be supplied to both reformers. It is also possible to make maximum use of the reforming capacity of both reformers.

  In the fuel cell module according to the present invention, the gas to be reformed can be selectively supplied to only one of the first reformer and the second reformer to the gas to be reformed pipe. It is also preferable to provide a supply switching unit.

  According to this preferred embodiment, the gas to be reformed can be reliably supplied selectively to only one of the first reformer and the second reformer. Therefore, by supplying the gas to be reformed only to the first reformer having a small heat capacity when starting the fuel cell module, it is possible to reliably reform the gas to be reformed and supply it to the fuel cell. As a result, the reducing atmosphere of the fuel electrode of the fuel cell can be maintained by supplying less reformed gas at startup.

  In the fuel cell module according to the present invention, the first reformer and the second reformer are connected by a fuel gas pipe for allowing a fuel gas to pass therethrough, and the first reformer and the It is also preferable that the gas to be reformed flowing into one of the second reformers is reformed and flows into the other.

  According to this preferred embodiment, from a small amount of gas to be reformed to a large number of gases to be reformed without using means for selectively supplying the gas to be reformed to the first reformer and the second reformer. Can be reliably modified. More specifically, when a small amount of gas to be reformed is supplied, reforming is mainly performed on the first reformer side, and substantially no reforming is performed on the second reformer before or after that. Fuel gas is supplied to the fuel cell. When a large amount of gas to be reformed is supplied, reforming is mainly performed on the second reformer side, and the fuel gas is supplied to the fuel cells. Therefore, the reducing atmosphere of the fuel electrode of the fuel cell can be maintained by supplying less reformed gas at startup.

  In the fuel cell module according to the present invention, the gas to be reformed that has flowed into the first reformer is reformed and flows into the second reformer, and in the flow path, It is also preferable that the first reformer is disposed upstream of the second reformer.

  According to this preferred embodiment, the reformed gas is first reformed in the first reformer, and then the reformed fuel gas is sent to the second reformer. Since the first reformer is disposed on the upstream side of the second reformer, that is, on the side closer to the combustion section, heat can be effectively applied to the first reformer. Accordingly, heat is effectively given by the first reformer having a small heat capacity and easy to give heat to the reformed gas passing through the interior, and the reformed gas is allowed to flow into the first reformer first. The gas to be reformed can be reliably reformed. That is, since the steam sent together with the gas to be reformed is reliably used for reforming, even if it is sent to the second reformer after that, the steam is consumed for reforming and the partial pressure is lowered. It is possible to lower the dew point temperature at which dew condensation occurs in the quality device. Moreover, since higher-order hydrocarbons are reformed in the first reformer, it is possible to suppress the precipitation of carbon in the second reformer.

  The fuel cell module according to the present invention further includes a combustion catalyst for burning the remaining fuel gas and oxidant gas reacted in the plurality of fuel cells, and the first reformer includes the combustion catalyst. It is also preferable that it is arranged on the downstream side.

  According to this preferable aspect, the first reformer having a small heat capacity is disposed downstream of the combustion catalyst, that is, at a place where the heat of the fuel gas burned from the early timing of operation by the combustion catalyst can be received more effectively. Therefore, heat can be effectively applied by the first reformer. Therefore, it becomes possible to more effectively apply heat to the first reformer that has a small heat capacity and easily applies heat to the gas to be reformed that passes through the inside, and the gas to be reformed that passes through the first reformer is reduced. It can be reformed with less fuel gas combustion. As a result, the reducing atmosphere of the fuel electrode of the fuel cell can be maintained by supplying less reformed gas at startup.

  The fuel cell module according to the present invention further includes an oxidant gas supply unit that distributes an oxidant gas to each of the plurality of fuel cells, wherein the first reformer is upstream of the oxidant gas supply unit. It is also preferable that it is arranged on the side.

  According to this preferable aspect, since the first reformer is arranged upstream of the oxidant gas supply unit, the heat of the exhaust gas is lost by heat exchange with the oxidant gas supply unit. Before the first reformer can be received. Therefore, it becomes possible to more effectively apply heat to the first reformer that has a small heat capacity and easily applies heat to the gas to be reformed that passes through the inside, and the gas to be reformed that passes through the first reformer is reduced. It can be reformed with less fuel gas combustion. As a result, the reducing atmosphere of the fuel electrode of the fuel cell can be maintained by supplying less reformed gas at startup.

  In the fuel cell module according to the present invention, it is also preferable that the first reformer is disposed at a substantially center of the container in a direction in which the plurality of fuel cell sides are seen from the combustion portion.

  In the flow path of the fuel cell module according to the present invention, the temperature in the vicinity of the outer periphery of the container is lowered due to heat radiation in the direction of seeing the plurality of fuel battery cells from the combustion portion, and the temperature at the approximate center of the container is Can be the highest. Therefore, in this preferred embodiment, by disposing the first reformer at a position where the temperature can be the highest, it becomes possible to efficiently transfer heat to the first reformer and pass through the first reformer. The reformed gas can be reformed by burning less fuel gas. As a result, the reducing atmosphere of the fuel electrode of the fuel cell can be maintained by supplying less reformed gas at startup.

  The fuel cell module according to the present invention further includes an evaporator for generating water vapor used to reform the gas to be reformed into fuel gas, and the evaporator includes the first evaporator and the first evaporator. The first evaporator is configured so that the heat capacity of the first evaporator is smaller than the heat capacity of the second evaporator, and the first evaporator is more than the second evaporator. It is also preferable that it is disposed on the upstream side of the flow path.

  In the present invention, the reformer is divided into two reformers, a first reformer and a second reformer, and the divided first reformer and second reformer are generated in the combustion section. By arranging the exhaust gas in a flow path that leads the outside of the container, the heat generated in the combustion section can be used. Furthermore, since the heat capacity of the first reformer is configured to be smaller than the heat capacity of the second reformer, the first reformer is adapted to the amount of fuel gas required at the start of operation. It can be formed, and it is configured to avoid consuming more fuel gas than necessary. When reforming the gas to be reformed in the first reformer and the second reformer, steam is required. Therefore, in this preferred embodiment, the evaporator for generating water vapor is divided into the first evaporator and the second evaporator in accordance with the division of the reformer, and the heat capacity of the first evaporator is the second. It comprises so that it may become smaller than the heat capacity of an evaporator, and the 1st evaporator is arrange | positioned in the upstream of the flow path rather than the 2nd evaporator. As described above, the first evaporator having a small heat capacity is arranged on the upstream side, that is, the side closer to the combustion section than the second starter having a large heat capacity. Can be given. Accordingly, the first evaporator having a small heat capacity and easily giving heat to the water passing through the inside can be more effectively heated. It can be. As a result, the amount of water can be reduced as well as the amount of gas to be reformed can be reduced at startup, and the reducing atmosphere of the fuel electrode of the fuel cell can be maintained.

  The fuel cell module according to the present invention preferably further includes a supply water pipe for supplying water to the first evaporator and the second evaporator in parallel.

  According to this preferred aspect, the first and second evaporators having different heat capacities are provided with the supply water pipes that can supply water in parallel, so that, for example, according to the operation status of the fuel cell module. Thus, water can be selectively supplied to the side of the evaporator having an appropriate evaporation capacity, and water can be supplied to both evaporators to make the most of the evaporation capacity of both evaporators.

  In the fuel cell module according to the present invention, the supply water pipe may be provided with a water supply switching unit for selectively supplying water to only one of the first evaporator and the second evaporator. preferable.

  According to this preferable aspect, water can be selectively and reliably supplied to only one of the first evaporator and the second evaporator. Therefore, by supplying water only to the first evaporator having a small heat capacity when starting the fuel cell module, it is possible to reliably evaporate a small amount of water and supply it to the reformer as water vapor. As a result, the reducing atmosphere of the fuel electrode of the fuel cell can be maintained by supplying less water at the time of startup.

  In the fuel cell module according to the present invention, it is also preferable that the first evaporator is disposed on the downstream side of the flow path with respect to the first reformer.

  According to this preferred embodiment, since the first reformer that needs to be heated to 500 ° C. or higher is disposed upstream of the first evaporator that may be heated to 100 ° C. or higher, the heat of the exhaust gas is reduced. It can be received by the first reformer before it is deprived of heat exchange with the first evaporator. Therefore, it becomes possible to more effectively apply heat to the first reformer that has a small heat capacity and easily applies heat to the gas to be reformed that passes through the inside, and the gas to be reformed that passes through the first reformer is reduced. It can be reformed with less fuel gas combustion. As a result, the reducing atmosphere of the fuel electrode of the fuel cell can be maintained by supplying less reformed gas at startup.

  Moreover, in a fuel cell provided with the fuel cell module according to the present invention, a fuel cell having the above-described effects can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic perspective view in which the fuel cell module FC according to this embodiment is partially broken. The fuel cell module FC is configured as a device for generating electric power by causing an electrochemical reaction between fuel gas and air (oxidant gas).

  The fuel cell module FC includes a fuel cell 2, current collecting members 3 and 4, a current collecting rod 5, an air header 6 (oxidant gas supply unit), an air supply pipe 7, and a module container 8 (container). And an insulating heat insulating member 9 and a heat insulating member 10.

The fuel battery cells 2 are configured as fuel battery cell stacks (not explicitly shown in FIG. 1) for every 12 of the 2 rows × 6 rows, and are housed in the module container 8. Each fuel cell 2 has a bottomed cylindrical shape and is formed of a ceramic material and forms a multilayer structure of an air electrode, a solid oxide electrolyte, and a fuel electrode from the inside to the outside of the cylinder. When air is in contact with the inner wall of the fuel cell 2, that is, the air electrode, and fuel gas is in contact with the outer wall, that is, the fuel electrode, O ²⁻ ions move in the cell to cause an electrochemical reaction, and there is a potential difference between the air electrode and the fuel electrode. As a result, electricity is generated. The electricity generated by the fuel cell 2 is collected by the current collecting members 3 and 4 and taken out by the current collecting rod 5.

  The air supplied to each fuel cell 2 is supplied by distributing the air supplied to the air header 6 through the air supply pipe 7. In the present embodiment, three air headers 6 are provided, and an air supply pipe 7 is connected to each air header 6. The upstream side of the air supply pipe 7 is connected to an air supply source.

  The air header 6 serves to temporarily store and raise the temperature of air supplied to each fuel battery cell 2 and also to distribute air to each fuel battery cell 2. The air header 6 is also for distributing the flow path of the air supplied to each fuel cell 2 to a plurality of systems according to the number of the fuel cells 2, so that the air header 6 corresponds to the number of the fuel cells 2. The placement quantity is increased or decreased.

  The fuel gas supplied to each fuel cell 2 is supplied from below each fuel cell 2 (details will be described later).

  The fuel cell 2, the current collecting members 3 and 4, and the air header 6 are accommodated in a rectangular parallelepiped module container 8. The module container 8 is made of a heat-resistant alloy material such as Inconel or stainless steel because it becomes hot during operation. Moreover, it has a sealed structure in order to prevent fuel gas and air from leaking outside. Inside the module container 8, an insulating heat insulating member 9 is provided to insulate the fuel cell 2 and the module container 8 and keep the inside of the module container 8 warm. The insulating heat insulating member 9 is made of alumina fiber or the like. The module container 8 is further entirely covered with a heat insulating member 10 in order to keep the operating temperature stable.

  Then, the arrangement | positioning aspect of the fuel cell 2 is demonstrated, referring FIG. FIG. 2 is a cross-sectional view in the direction in which the fuel cell 2 side is seen from the air header 6 side in FIG. The fuel cell assembly 21 includes a plurality of fuel cell stacks 21a, 21b, and 21c. Each fuel cell stack 21a, 21b, 21c has 12 fuel cells 2, and each fuel cell 2 is arranged in 2 rows (x direction in the figure) × 6 rows (y direction in the figure). Has been.

  Each fuel cell 2 has a bottomed cylindrical shape, and is arranged with its opening 2a facing the air header 6 side. Each fuel cell 2 is electrically connected in 2 parallel × 6 series via an inter-cell current collecting member 13 and a conductive cell connecting member 14. The number and arrangement of the fuel cells 2 are appropriately selected according to the power generation capacity and the like.

  The fuel cell stacks 21a, 21b, and 21c are arranged in three rows (in the x direction in the figure) at a predetermined interval, and constitute a fuel cell assembly 21 having 36 fuel cells 2. ing. Each of the fuel cell stacks 21a, 21b, and 21c is electrically connected in series via the current collecting member 3. The current collecting member 4 is connected to the ends of the fuel cell stacks 21a, 21c arranged at both ends of the fuel cell stacks 21a, 21b, 21c connected in series in this way. Since the current collecting member 4 is connected to the current collecting rod 5, electric power can be taken out through the current collecting rod 5.

  Each of the fuel cell stacks 21a, 21b, and 21c is provided with an insulating plate 16 so as to contact a pair of side surfaces in which the fuel cells 2 are arranged in six rows. Further, a heat conduction plate 15 is disposed between adjacent insulating plates 16. A heat conducting plate 15 is also disposed between the fuel cell stacks 21a and 21c and the insulating heat insulating member 9. An insulating rod 11 is disposed between the heat conducting plate 15 and the current collecting members 3 and 4.

  By arranging the heat conduction plate 15 in this way, even when the temperature of the fuel cell 2 is partially increased locally, heat easily moves from the high temperature portion to the low temperature portion via the heat conduction plate 15. Thus, the temperature distribution of the fuel cell 2 can be made uniform.

  Further, as described above, the insulating plate 16 and the insulating rod 11 are arranged, so that the electrical insulation between the heat conducting plate 15 and the fuel cell 2 and the heat conducting plate 15 and the current collecting members 3 and 4 Electrical insulation is ensured.

  Subsequently, an arrangement mode of the fuel cells 2 and a supply mode of the fuel gas and air will be described with reference to FIG. FIG. 3 is a longitudinal sectional view of the fuel cell module FC and shows the inside of the module container 8.

  As shown in FIG. 3, a fuel gas dispersion chamber 17 for uniformly dispersing the fuel gas introduced into the module container 8 is disposed below the module container 8. In the fuel gas dispersion chamber 17, a pre-dispersion plate 18 for pre-dispersing the fuel gas is disposed. The preliminary dispersion plate 18 is made of alumina, for example, and the fuel gas vent holes 19 are uniformly formed. Further, a fuel gas dispersion material 30 made of, for example, Ni foam is disposed above the preliminary dispersion plate 18. A fuel gas supply pipe 22 is provided on the upstream side (lower side in the figure) of the fuel gas dispersion chamber 17. Further, a fuel gas dispersion plate 23 is provided between the module container 8 and the fuel gas dispersion chamber 17 to allow the fuel gas to flow from the fuel gas dispersion chamber 17 to the module container 8. The fuel gas distribution plate 23 has a plurality of fuel gas supply holes 24 formed therein.

  In addition, a plurality of air introduction pipes 25 for introducing air into the air electrode of the fuel cell 2 are connected to the air header 6 disposed above the fuel cell assembly 21. The air introduction pipe 25 is inserted into the pipe of the fuel cell 2, and its lower end extends to the vicinity of the bottom surface of the fuel battery cell 2.

  In the module container 8, a rectangular partition plate 26 formed along the direction perpendicular to the longitudinal direction of the fuel cell 2 is provided. The partition plate 26 is made of a laminate of alumina fibers formed into a blanket or a felt. In the module container 8, a combustion chamber 27 (combustion part) is formed on the upper side partitioned by the partition plate 26, and a power generation chamber 28 is formed on the lower side. Here, the combustion chamber 27 mixes and burns surplus fuel gas that has not contributed to the reaction in the power generation chamber 28 and surplus air that has not contributed to the reaction in the cylinder of each fuel cell 2. Space. The power generation chamber 28 is a space for bringing the fuel gas introduced from the fuel gas supply hole 24 into contact with each fuel cell 2 and generating an electrochemical reaction with the air flowing in the pipe of each fuel cell 2 to generate power. It is.

  The partition plate 26 is inserted with a plurality of cylindrical fuel gas discharge pipes (not shown) made of alumina, for example, for discharging the remaining fuel gas from the power generation chamber 28 to the combustion chamber 27. Therefore, a plurality of gas discharge holes for allowing the fuel gas to pass from the power generation chamber 28 to the combustion chamber 27 are formed in the partition plate 26.

  A combustion catalyst 40 is disposed between the partition plate 26 and the air header 6. The combustion catalyst 40 is a catalyst for mixing and burning surplus fuel gas that did not contribute to the reaction in the power generation chamber 28 and surplus air that did not contribute to the reaction in the cylinder of each fuel cell 2. Yes, a mixed gas that does not ignite unless it is 500 ° C. or higher in spontaneous ignition can be ignited at about 150 ° C. to 250 ° C.

  On the opposite side of the fuel cell 2 with the combustion catalyst 40 in between, a flow path 50 that guides exhaust gas generated in the combustion chamber 27 to the outside of the module container 8 is formed. In the flow path 50, a first reformer 41, a first evaporator 43, an air header 6, a second reformer 42, and a second evaporator 44 are arranged in this order from the upstream side (fuel cell 2 side). Has been.

  The first reformer 41 is configured to have a smaller heat capacity than the second reformer 42. A to-be-reformed gas pipe 51 for supplying city gas or the like as a to-be-reformed gas to the first reformer 41 and the second reformer 42 is provided. The reformed gas pipe 51 is branched into a first gas pipe 51 a connected to the first reformer 41 and a second gas pipe 51 b connected to the second reformer 42. The first gas pipe 51a is provided with a valve 45 (supply switching section), and the second gas pipe 51b is provided with a valve 46 (supply switching section). Therefore, the amount of the gas to be reformed flowing into the first reformer 41 and the second reformer 42 can be adjusted by opening and closing the valves 45 and 46 independently. The reformed gas reformed by the first reformer 41 and the second reformer 42 is supplied to the fuel gas supply pipe 22 as a fuel gas.

  The first evaporator 43 is configured to have a smaller heat capacity than the second evaporator 44. A supply water pipe 52 for supplying water to the first evaporator 43 and the second evaporator 44 is provided. The supply water pipe 52 is branched into a first water pipe 52 a connected to the first evaporator 43 and a second water pipe 52 b connected to the second evaporator 44. The first water pipe 52a is provided with a valve 47 (water supply switching section), and the second water pipe 52b is provided with a valve 48 (water supply switching section). Therefore, the amount of water flowing into the first evaporator 43 and the second evaporator 44 can be adjusted by opening and closing the valves 47 and 48 independently. A pipe extending from the first evaporator 43 is connected to the first gas pipe 51a so that water vapor generated in the first evaporator 43 is mixed into the gas to be reformed flowing into the first reformer 41. ing. A pipe extending from the second evaporator 44 is connected to the first gas pipe 51b so that water vapor generated in the second evaporator 44 is mixed into the gas to be reformed flowing into the second reformer 42. ing.

  In the example described with reference to FIG. 3, the reformed gas pipe 51 is configured to supply the reformed gas in parallel to the first reformer 41 and the second reformer 42. However, it is also preferable to connect the first reformer 41 and the second reformer 42 with a series pipe. This example will be described with reference to FIG. FIG. 4 is a block diagram for explaining an example in which the first reformer 41 and the second reformer 42 are connected in series.

  The arrangement order of the first reformer 41, the first evaporator 43, the air header 6, the second reformer 42, and the second evaporator 44 in the example shown in FIG. 4 is the same as the example shown in FIG. is there. A to-be-reformed gas pipe 53 for supplying city gas or the like as a to-be-reformed gas to the first reformer 41 and the second reformer 42 is provided. The reformed gas pipe 53 is connected only to the first reformer 41. A fuel gas pipe 54 connecting the first reformer 41 and the second reformer 42 is provided, and the gas to be reformed flowing into the first reformer 41 from the gas reformed pipe 53 is the first All or part of the reformer 41 is reformed and sent to the second reformer 42. The reformed gas pipe 53 is provided with a valve 49, and the gas to be reformed (fuel gas) flowing into the first reformer 41 and the second reformer 42 by opening and closing the valve 49. The amount of can be adjusted. The reformed gas reformed by the first reformer 41 and the second reformer 42 is supplied to the fuel gas supply pipe 22 as a fuel gas.

  As described above, since the first reformer 41 is configured to have a smaller heat capacity than the second reformer 42, the outer shape thereof is also configured to be smaller than the second reformer 42. . When the second reformer 42 is provided along the inner wall surface of the module container 8 in the direction in which the fuel cell 2 is seen from the combustion chamber 27, the first reformer 41 smaller than the second reformer 42 is a module. It arrange | positions in the approximate center of the container 8. FIG. This is because the module container 8 is arranged at the highest temperature in order to efficiently transfer heat by the first reformer 41. Further, as shown in FIG. 5, the first reformer 41 is further divided into three parts to be a first reformer 41a, a first reformer 41b, and a first reformer 41c. It is also preferable to dispose at approximately the center.

  As described above, the reformer is divided into the first reformer 41 and the second reformer 42, and the exhaust gas generated in the combustion chamber 27 is disposed in the flow path 50 that is led to the outside of the module container 8. The effect obtained will be described with reference to FIGS. FIG. 6 is a graph showing the relationship between the temperature and the fuel flow rate when the fuel cell module FC in the configuration of the present embodiment is operated. FIG. 7 is a graph showing the relationship between the temperature and the fuel flow rate when the fuel cell module is operated when the reformer has a single configuration for comparison and the heat capacity is equivalent to that of the second reformer 42. It is. In FIG. 6, the thickest solid line indicates the power generation output, the middle solid line indicates the flow rate (fuel flow rate) of the reformed gas (fuel gas), the thinnest solid line indicates the temperature of the fuel cell 2, and the dotted line indicates the first modification. The broken line indicates the temperature of the mass device 41, the broken line indicates the temperature of the second reformer 42, and the alternate long and short dash line indicates the temperature of the exhaust gas (combustion chamber temperature). In FIG. 7, the thickest solid line indicates the power generation output, the middle thick solid line indicates the flow rate (fuel flow rate) of the gas to be reformed (fuel gas), the thinnest solid line indicates the temperature of the fuel cell 2, and the broken line indicates the reformer. The alternate long and short dash line indicates the temperature of the exhaust gas (combustion chamber temperature). In FIG. 6 and FIG. 7, the operation is controlled so that the time from the start of operation until the predetermined power generation output is obtained is equal.

  As shown in FIG. 6, after the operation of the fuel cell module FC is started, the reformed gas is supplied as the fuel gas in an unreformed state, and the combustion chamber 27 is ignited at time t1. Thereafter, in order to bring the first reformer 41 to a reformable temperature (500 ° C.), combustion in the combustion chamber 27 is continued while supplying a relatively small amount of fuel gas. If the combustion in the combustion chamber 27 is continued, the first reformer 41 reaches the reformable temperature at time t2, the reforming of the reformed gas is started, and the reformed fuel gas is supplied to the fuel battery cell 2. Supplied. Accordingly, it is possible to maintain the reducing atmosphere of the fuel electrode of the fuel cell 2 that is required at the time of startup. Thereafter, since the second reformer 42 reaches the reformable temperature (500 ° C.) at time t3, the fuel flow rate is increased to an amount corresponding to the steady operation state, and power generation is started.

  On the other hand, assuming that the reformer has a single configuration, as shown in FIG. 7, the reformer configured with a heat capacity corresponding to the heat capacity of the second reformer 42 is set to a reformable temperature (500 ° C.). Therefore, the combustion of the fuel chamber 27 is continued while supplying a relatively large amount of fuel gas. When the combustion in the combustion chamber 27 is continued, the reformer reaches the reformable temperature at time t4, the reforming of the reformed gas is started, and the reformed fuel gas is supplied to the fuel cells.

  When FIG. 6 and FIG. 7 are compared, a remarkable difference is observed in the supply amount of the reformed gas (fuel gas) at the start-up before the steady operation. The supply amount of the gas to be reformed (fuel gas) at the time of starting the fuel cell module FC of the present embodiment only needs to raise the temperature of only the first reformer 41, and therefore is relatively more than that shown in FIG. A small amount of supply is sufficient.

  Next, the configuration of the fuel cell FCS using the fuel cell module FC will be described with reference to FIG. FIG. 8 is a block diagram showing the configuration of the fuel cell FCS. As shown in FIG. 8, the fuel cell FCS includes a fuel cell module FC, a fuel supply unit FP, an air supply unit AP, a water supply unit WP, a power extraction unit EP, and a control unit CS. . The fuel supply unit FP, the air supply unit AP, the water supply unit WP, and the power extraction unit EP constitute an auxiliary device AD of the fuel cell FCS.

  The fuel supply unit FP is a part that supplies fuel gas from a city gas pipe as a fuel supply source to the fuel cell module FC, and includes a fuel pump and an electromagnetic valve. The fuel gas supplied from the fuel supply unit FP is sent out to the fuel gas supply pipe 22.

  The air supply part AP is a part that supplies air from the atmosphere as an air supply source to the solid oxide fuel cell module 1, and has an air blower and an electromagnetic valve. The air supplied from the air supply unit AP is sent out to the air supply pipe 8.

  The water supply unit WP is a part that supplies water from a water pipe as a water supply source to the fuel cell module FC, and includes a water pump and an electromagnetic valve. The water supplied from the water supply unit WP is sent out as water vapor inside the fuel cell module FC.

  The power extraction unit EP is a part that extracts electric power from the fuel cell module FC, and includes a power conversion device such as an inverter. The power extraction unit EP is connected to the current collecting rod 5 and is configured to send the converted power to a power supply destination.

  The control unit CS is a part for controlling each of the fuel supply unit FP, the air supply unit AP, the driving auxiliary device AD, and the power extraction unit EP, and includes a CPU and a ROM. The operation of the fuel cell module FC is executed based on an instruction signal from the control unit CS.

  The operation of the fuel cell FCS configured as described above will be described. The power generation chamber 28 is heated to a temperature (700 to 1000 ° C.) at which an electrochemical reaction occurs. Air is supplied from the air supply unit AP to the air supply pipe 7 and stored in the air header 6. The stored air flows downward in the plurality of air introduction pipes 25 and flows out into the cylinder of the fuel cell 2 from the lower end. The outflowed air flows upward in the cylinder of the fuel battery cell 2. At this time, the air is brought into contact with the air electrode and subjected to the reaction. The air not consumed by the reaction reaches the combustion chamber 27 from the opening 2 a of the fuel cell 2.

  Further, the fuel gas is supplied from the fuel supply unit FP to the fuel gas supply pipe 22 and stored in the fuel gas dispersion chamber 17. The stored fuel gas is introduced into the power generation chamber 28 from a plurality of fuel gas supply holes 24 formed in the fuel gas dispersion plate 23, and flows upward while surrounding each fuel cell 2 in the power generation chamber 28. At this time, the fuel gas is brought into contact with the fuel electrode for reaction. The fuel gas not consumed by the reaction reaches the combustion chamber 27 through a fuel gas discharge pipe (not shown) of the partition plate 26.

  The remaining fuel gas and the remaining air that have reached the combustion chamber 27 are combusted using a predetermined ignition device, and exhaust gas is discharged out of the combustion chamber 27 from an exhaust gas pipe connected to the upper wall of the module container 8. Is done. Since this exhaust gas becomes high temperature, it is used as a heat source for heating the power generation chamber 28.

It is the schematic perspective view which fractured partially the fuel cell module concerning this embodiment. FIG. 2 is a cross-sectional view in a direction in which the fuel cell side is seen from the air header side in FIG. 1. It is a longitudinal cross-sectional view of a fuel cell module. It is a figure which shows the example of arrangement | positioning of the reformer in a fuel cell module. It is a figure which shows the example of arrangement | positioning of the reformer in a fuel cell module. It is a figure which shows the temperature and fuel flow volume in this embodiment. It is a figure which shows the temperature and fuel flow volume in the conventional structure. It is a block diagram which shows the structure of a fuel cell.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Fuel cell, 3, 4 ... Current collection member, 5 ... Current collection rod, 6 ... Air header, 7 ... Air supply pipe, 8 ... Module container, 9 ... Insulation heat insulation member, 10 ... Heat insulation member, 21 ... Fuel Battery cell assembly 25 ... Air introduction pipe 26 ... Partition plate 27 ... Combustion chamber 28 ... Power generation chamber 29 ... Fuel gas discharge hole FC ... Fuel cell module FCS ... Fuel cell

Claims (14)

A plurality of fuel cells operated by fuel gas and oxidant gas;
A reformer for reforming the gas to be reformed into fuel gas;
A fuel cell module comprising a container for housing the plurality of fuel cells,
The container is formed with a combustion portion for burning the remaining fuel gas and oxidant gas reacted in the plurality of fuel cells.
In the flow path through which exhaust gas generated in the combustion section is guided to the outside of the container, the reformer is divided into a first reformer and a second reformer,
The fuel cell module, wherein the heat capacity of the first reformer is smaller than the heat capacity of the second reformer.   2. The fuel cell module according to claim 1, wherein the first reformer is disposed upstream of the second reformer in the flow path.   The fuel cell module according to claim 1, further comprising a reformed gas pipe that supplies a gas to be reformed in parallel to each of the first reformer and the second reformer.   The supply gas switching portion for selectively supplying the gas to be reformed to only one of the first reformer and the second reformer is provided in the gas to be reformed pipe. Item 4. The fuel cell module according to Item 3.   The first reformer and the second reformer are connected by a fuel gas pipe for allowing a fuel gas to pass therethrough, and flow into either the first reformer or the second reformer. 2. The fuel cell module according to claim 1, wherein the reformed gas is reformed and flows into the other. The gas to be reformed flowing into the first reformer is reformed and configured to flow into the second reformer,
6. The fuel cell module according to claim 5, wherein the first reformer is disposed upstream of the second reformer in the flow path. A combustion catalyst for burning residual fuel gas and oxidant gas reacted in the plurality of fuel cells;
The fuel cell module according to any one of claims 1 to 6, wherein the first reformer is disposed downstream of the combustion catalyst. An oxidant gas supply unit that distributes the oxidant gas to each of the plurality of fuel cells,
The fuel cell module according to any one of claims 1 to 7, wherein the first reformer is disposed upstream of the oxidant gas supply unit.   The said 1st reformer is arrange | positioned in the approximate center of the said container in the direction which sees the said some fuel cell side from the said combustion part, The any one of Claims 1-8 characterized by the above-mentioned. The fuel cell module described. Equipped with an evaporator for generating water vapor used to reform the gas to be reformed into fuel gas,
The evaporator is divided and arranged in a first evaporator and a second evaporator,
The heat capacity of the first evaporator is configured to be smaller than the heat capacity of the second evaporator,
The fuel cell module according to any one of claims 1 to 9, wherein the first evaporator is disposed on an upstream side of the flow path with respect to the second evaporator.   The fuel cell module according to claim 10, further comprising a supply water pipe that supplies water to the first evaporator and the second evaporator in parallel.   The fuel cell according to claim 11, further comprising a water supply switching unit configured to selectively supply water to only one of the first evaporator and the second evaporator in the supply water pipe. module.   The fuel cell module according to any one of claims 10 to 12, wherein the first evaporator is disposed downstream of the first reformer than the first reformer.   A fuel cell comprising the fuel cell module according to claim 1.

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