JP2013008455A - Solid oxide fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell device that has heat-absorption relaxation means that relaxes local endothermic conditions potentially occurring in a plurality of power generation cells in a module container, in response to an operating condition of a reformed gas utilization device.SOLUTION: A solid oxide fuel cell device includes: a plurality of cells that generate power with fuel gas and oxidant gas; a module container that houses the cells; an external reformer that is arranged on part of an external surface of an external wall of the module container and that uses heat generated during power generation in the cells so as to reform gas to be reformed, by endothermic reaction, into reformed gas for use in a reformed gas utilization device of another system; and heat-absorption relaxation means that spreads and thereby relaxes local endothermic conditions that potentially occur in parts of the cells arranged at positions facing the external reformer through the external wall.

Description

  The present invention relates to a solid oxide fuel cell device that generates power using a fuel gas and an oxidant gas.

  A solid oxide fuel cell (hereinafter also referred to as “SOFC”) uses an ion conductive solid oxide as an electrolyte, and electrodes are attached to both sides of the fuel cell and an oxidant gas (air, The fuel cell device performs power generation by generating a power generation reaction at a relatively high temperature.

  In general, the SOFC includes a fuel cell assembly having a plurality of fuel cells in which an oxide is sandwiched between a fuel electrode layer and an air electrode layer, and includes a fuel gas and an oxidant gas (air, oxygen, etc.). ) And flow. At that time, a gas to be reformed (for example, city gas such as methane gas) is supplied from the outside of the SOFC, and the gas to be reformed is introduced into a reformer in which a reforming catalyst is housed to perform hydrogen-rich reforming. After reforming into gas, the reformed gas is supplied to the fuel cell assembly.

  The SOFC can operate with high power generation efficiency due to a small voltage drop. However, on the other hand, it takes a long time to start and stop the SOFC, the operating temperature of the fuel cell in the power generation state exceeds 800 ° C., and in some cases may exceed 900 ° C. The inconvenience of handling for starting and stopping and the exhaust heat method often become technical problems. In addition, the SOFC has a low load following capability for a change in power consumption from a fuel cell user, and it is difficult to increase or decrease the amount of power generation instantaneously.

In contrast, a polymer electrolyte fuel cell (Polymer Electrolyte)
Fuel Cell (hereinafter also referred to as “PEFC”) has low power generation efficiency compared to SOFC, but has a short start-up time and high load-following capability for changes in power usage from fuel cell users It has characteristics. In addition, PEFC also requires a reformer to reform the gas to be reformed such as city gas to be rich in hydrogen. If an endothermic reaction is selected as a hydrogen generation reaction to be executed in the reformer, It is also possible to effectively use the exhaust heat generated in the SOFC operating at a high temperature.

  Based on this concept, by incorporating the PEFC into the system, the exhaust heat from the SOFC operating at high temperature is not wasted, but it is effectively used in the reformer used for the PEFC, resulting in high power generation efficiency and high load. There has been proposed a hybrid fuel cell system that achieves both followability (see Patent Document 1).

JP 2001-266924 A

  In the conventional technology described above, it is possible to reuse the exhaust heat from the SOFC fuel cell operating at a high temperature in a reformer of another system. However, when using a combination of an SOFC with a low load following capability and a PEFC with a high load following capability, it is necessary to change the operating state of the PEFC in cooperation with the SOFC in order to respond to a sudden change in power consumption by the user. There is. When the operating state of the PEFC is changed in this way, it is necessary to change the amount of hydrogen supplied to the PEFC. Therefore, the amount of gas to be reformed used in the reformer on the PEFC side also changes.

  Various reactions can be used to generate hydrogen in a reformer used in a general fuel cell system, but a large amount of hydrogen is instantaneously required as a fuel gas in a PEFC with high load following capability. It is assumed that Therefore, in the PEFC, the steam reforming reaction SR, which is the reforming reaction having the highest hydrogen yield, can be used. Here, the steam reforming reaction SR is an endothermic reaction. Therefore, when the steam reforming reaction SR is used in the PEFC reformer, when the amount of gas to be reformed flowing into the reformer increases, a local endothermic reaction, that is, a local temperature drop occurs in the reformer. And a local heat absorption part may be generated in a part of the SOFC-side fuel cell arranged in the vicinity of the reformer. In particular, in some of the cells in the SOFC module operating at a high temperature, the occurrence of such an endothermic part, which is also referred to as a local low temperature part, causes temperature unevenness between the fuel cells in the SOFC module, As a result of research conducted by the inventors, it has been found that non-uniform power generation capacity occurs between the fuel cells, which adversely affects the durability of the SOFC.

  Furthermore, hydrogen vehicles and fuel cell vehicles using hydrogen as fuel are used as equipment that reuses exhaust heat from SOFC fuel cells operating at high temperatures to generate hydrogen in a separate reformer. Equipment for using reformed gas, such as hydrogen stations, is also conceivable. In this way, the hydrogen station cooperating with the SOFC not only generates power itself for management and operation of the hydrogen station itself, but also can supply electricity in addition to hydrogen. Such a hydrogen station can be assumed to be required to instantaneously increase the amount of hydrogen supply in response to a hydrogen supply request from a user. There is a concern that temperature unevenness occurs between the fuel cells, and the durability of the SOFC is adversely affected.

  The present invention has been made in view of such problems and knowledge, and the purpose thereof is that a reformed gas utilization device represented by PEFC can be operated in a desired state according to a user's request, and To provide a solid oxide fuel cell device capable of relieving a local endothermic state that may occur in a plurality of fuel cells in a module container, which may occur depending on the operating state of the reformed gas utilization device. It is in.

  In order to solve the above-mentioned problem, a solid oxide fuel cell device according to the present invention is a solid oxide fuel cell device, and includes a plurality of cells that generate power by using a fuel gas and an oxidant gas, A module container that accommodates the cell and a part of the outer surface of the outer wall of the module container, and heat generated during power generation in the plurality of cells is used to reform the gas to be reformed by an endothermic reaction. An external reformer that reforms into a reformed gas for use in a gas utilization device, and can be locally generated in a part of a cell that is disposed at a position facing the external reformer across the outer wall An endothermic relaxation means is provided for relaxing by dispersing a typical endothermic state.

  The solid oxide fuel cell device according to the present invention utilizes the heat from the solid oxide fuel cell, and is reformed by a solid polymer fuel cell of a different system from the solid oxide fuel cell. By operating the external reformer that generates the reformed gas (hydrogen gas) used in the gas utilization device, the residual heat of the solid oxide fuel cell can be effectively utilized. At the same time, the reformed gas utilization device can also receive the supply of hydrogen without having a separate heating means for use in the external reformer. In the solid oxide fuel cell device according to the present invention, the external reformer is disposed on a part of the outer surface of the outer wall of the module container that accommodates the fuel cell, so that heat from the heat-generating cell is externally transmitted. It can be efficiently propagated to the reformer. By the way, when the amount of gas to be reformed used in the external reformer is increased or decreased by the load following operation of the reformed gas utilization device, the reforming reaction amount is increased or decreased, and finally the endothermic amount in the external reformer is increased. It is expected to increase or decrease. If it does so, there exists a concern that the endothermic state transmitted to the fuel cell in a solid oxide fuel cell device may change locally, and it may affect the specific cell in a module container. Therefore, in the present invention, there is provided an endothermic mitigation means for mitigating the local endothermic state that may occur in a part of the cells arranged at positions facing the external reformer with the outer wall interposed therebetween. This endothermic mitigation means eliminates temperature unevenness without excessively absorbing heat from specific cells, enabling uniform power generation reactions across the cells in the module container and improving durability as a fuel cell. To do. Furthermore, since the endothermic relaxation means relaxes the local endothermic state, the heat used for the reforming reaction can be efficiently propagated from the plurality of cells to the external reformer.

  In the solid oxide fuel cell device according to the present invention, the endothermic relaxation means includes a first region including a cell disposed at a position facing the external reformer across the outer wall, and the plurality of cells. It is also preferable that the heat transfer means thermally connect the second region including the remaining cells excluding the cells included in the first region.

  In this preferable aspect, even if there is a change in the endothermic state that occurs in the external reformer due to a request for increasing the amount of power used, the heat transfer means includes the first region where the local endothermic state is generated, Since heat is promoted to propagate to the second region where no endothermic state has occurred, the local endothermic state can be mitigated.

  In the solid oxide fuel cell device according to the present invention, it is preferable that the second region includes a cell that is disposed near the inner center of the module container and is in a high temperature state.

  In this preferred embodiment, the heat transfer means heats the second region including the cell disposed near the inner center of the module container and having the highest temperature, and the first region in which the local endothermic state occurs. Therefore, the heat from the higher-temperature cell can be propagated to the local heat absorption part, and the local heat absorption state can be more efficiently relaxed. Furthermore, in this preferred embodiment, the power generation capacity and durability of the solid oxide fuel cell device itself are further improved by effectively reducing temperature variations among all the fuel cells in the solid oxide fuel cell device. Can be improved.

  In the solid oxide fuel cell device according to the present invention, the endothermic relaxation means is a heat insulating means for insulating the inside and the outside of the module container, and the heat insulating means corresponds to the first region. A first heat insulating portion provided and a second heat insulating portion provided corresponding to the second region, the heat insulating performance in the first heat insulating portion and the heat insulating performance in the second heat insulating portion. It is also preferable to provide a difference and make the endothermic state propagating to the cell equal between the first heat insulating part and the second heat insulating part.

  In this preferable aspect, since there is a difference between the heat insulating performance in the first heat insulating portion and the heat insulating performance in the second heat insulating portion, the amount of heat transferred to the inside and outside of the module container in the first region, and in the second region A difference can be provided between the amount of heat transferred to the inside and outside of the module container. Therefore, even if a local endothermic state occurs in the first region, the influence on the cell can be adjusted compared to the second region, and the endothermic state propagating to the cell can be made uniform. A simple means of providing a difference in performance can alleviate the local endothermic state and more effectively prevent the cell temperature from decreasing.

  In the solid oxide fuel cell device according to the present invention, the heat insulating performance of the first heat insulating portion may be configured to be higher than the heat insulating performance of the second heat insulating portion.

  In this preferable aspect, since the heat insulation performance in the first heat insulation portion is higher than the heat insulation performance in the second heat insulation portion, the amount of heat transferred to the inside and outside of the module container in the first region is changed to the second region. The amount of heat transmitted to the inside and outside of the module container can be suppressed. Therefore, even if a local endothermic state occurs in the first region, it is possible to reduce the influence of the local endothermic state on the cells inside the module container and to improve the heat insulating performance in the first heat insulating portion by a simple means. The state can be relaxed.

  According to the present invention, solid oxidation that can alleviate a local endothermic state that can occur in a plurality of power generation cells in a module container in response to the operating state of a reformed gas utilization device represented by PEFC. A physical fuel cell device can be provided.

1 is a schematic perspective view of a solid oxide fuel cell device according to a first embodiment of the present invention. 2 is a cross-sectional view of the solid oxide fuel cell device according to the first embodiment of the present invention taken along the line II-II in FIG. 3 is a cross-sectional view of the solid oxide fuel cell device according to the first embodiment of the present invention, taken along the line III-III in FIG. It is the schematic which shows the change of the endothermic state which arises in the external reformer of the solid oxide fuel cell apparatus which concerns on 1st Embodiment of this invention. FIG. 3 is a schematic cross-sectional view of a solid oxide fuel cell device according to a second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components are denoted by the same reference symbols in the drawings, and overlapping descriptions are omitted as much as possible.

  A fuel cell system AP according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a conceptual diagram showing a schematic configuration of the fuel cell system AP. As shown in FIG. 1, the fuel cell system AP includes a solid oxide fuel cell device AP1 and a solid polymer fuel cell device AP2. 2 is a schematic cross-sectional view schematically showing a II-II cross section in FIG. 1 so that the inside of the solid oxide fuel cell apparatus AP1 in FIG. 1 can be seen.

  The solid oxide fuel cell apparatus AP1 includes a solid oxide fuel cell module AP1a and a pair of external reformers 1 and 1 '. The polymer electrolyte fuel cell device AP2 includes a polymer electrolyte fuel cell module AP2a and a hydrogen purification storage unit HB.

  The solid oxide fuel cell apparatus AP1 is configured as an apparatus for generating electric power by causing an electrochemical reaction between fuel gas and air (oxidant gas). The solid oxide fuel cell module AP1a includes a module container 4 for storing a plurality of fuel cells 7 and a pair of current collecting rods 5 and 5 'for taking out the generated current. The current collecting rods 5 and 5 'are connected to the inverter AP1v. The external reformers 1 and 1 ′ are arranged on the side wall surface of the module container 4 and are configured to generate a reformed gas used in the polymer electrolyte fuel cell device AP <b> 2.

  The hydrogen generated by the external reformers 1 and 1 'is sent to the hydrogen purification storage unit HB of the polymer electrolyte fuel cell device AP2, and after being purified to high purity hydrogen as necessary, it is buffered. Thereafter, the hydrogen stored in the hydrogen purification storage unit HB is sent to the polymer electrolyte fuel cell module AP2a to contribute to the power generation reaction. The polymer electrolyte fuel cell module AP2a is provided with an inverter AP2v so that the generated electricity can be taken out. As described above, a reformed gas utilizing device such as a hydrogen station connected to the external reformers 1 and 1 ′ can be used instead of the polymer electrolyte fuel cell device AP <b> 2 in the present embodiment.

  Subsequently, the solid oxide fuel cell apparatus AP1 will be described in more detail. The module container 4 has a substantially rectangular parallelepiped shape, and the outer wall member of the module container 4 corresponding to the front surface of the rectangular parallelepiped is positioned opposite to the module wall 4a and the module wall 4a, that is, the outer wall provided at the portion corresponding to the rear surface of the rectangular parallelepiped. The members are connected to the module wall 4c and the module walls 4a and 4c, and the outer wall members corresponding to the side surfaces of the rectangular parallelepiped are referred to as module walls 4b and 4d, respectively. Since the solid oxide fuel cell module AP1a is heated at the time of power generation, the constituent members of the module container 4 including the module walls are formed of a heat-resistant alloy material such as Inconel or stainless steel. It has a sealed structure to prevent supply gas such as air from leaking outside. Inside the module container 4, an insulating heat insulating member formed of alumina fiber or the like for insulating the fuel battery cell 7 and the module container 4 and keeping the inside of the module container 4 may be provided. In order to keep it stable, the whole or part of the outside of the module container 4 may be covered with an insulating heat insulating member.

  An oxidant gas supply source OS capable of supplying oxidant gas OG (air) to the fuel cell 7 in the module container 4 is connected above the module container 4 of the solid oxide fuel cell module AP1a. A fuel gas supply source FS capable of supplying the fuel gas FG to the fuel cells 7 in the module container 4 is connected below the module container 4. In the solid oxide fuel cell module AP1a, the air that is the oxidant gas OG supplied to the fuel cell 7 in the module container 4 passes through an air header (not shown) provided above the inside of the module container 4. And may be appropriately distributed and supplied to each fuel cell 7. The air header also serves to temporarily store air supplied to each fuel cell 7 and raise the temperature. Further, the fuel gas FG supplied to each fuel battery cell 7 is supplied from the lower side of each fuel battery cell 7. Here, the inflow position and the inflow direction of the oxidant gas OG and the fuel gas FG can be arbitrarily selected according to the shape of the fuel cell 7 inside the module container 4 and the like.

  The pair of current collecting rods 5, 5 ′ is provided on the outer surface of the module wall 4 c of the module container 4, and sends a direct current generated and generated by the fuel cell 7 in the module container 4 to the inverter AP 1 v. is doing. The inverter AP1v converts the direct current generated in the fuel cell 7 of the solid oxide fuel cell module AP1a into an alternating current.

The external reformer 1 in the solid oxide fuel cell apparatus AP1 generates a reformed gas used during operation of a reformed gas utilization device represented by PEFC in cooperation with the solid oxide fuel cell module AP1a. It is a gas reformer used for The external reformer 1 according to the present embodiment has a gas inlet 2 on the upper side and a gas outlet 3 on the lower side. Only the quality gas AG and water vapor are supplied to the gas inlet 2, and for example, the steam reforming reaction SR shown in the following chemical formula inside the external reformer 1,
C _m H _n + aH ₂ O → bCO + cH ₂ (1)
Progresses. In the embodiment shown in FIG. 2, the reformed gas (hydrogen) generated by the steam reforming reaction SR is supplied from the gas outlet 3 of the external reformer 1 to the polymer electrolyte fuel cell device AP2 to be solid. It is used for power generation in the polymer fuel cell module AP2a. As the reforming reaction proceeding inside the external reformer 1, a reaction with an endothermic reaction such as a steam reforming reaction SR or an autothermal reforming reaction ATR is selected. Requires a separate heat source for heat absorption. However, the external reformer 1 according to the present embodiment is directly attached to the module wall of the module container 4 of the solid oxide fuel cell module AP1a operating at a high temperature, and the module of the solid oxide fuel cell module AP1a. Since the container 4 itself acts as a heat source, heat for advancing / promoting the steam reforming reaction SR in the external reformer 1 is sufficiently supplied to the external reformers 1 and 1 ′.

Referring to FIG. 2, inside the module container 4 of the solid oxide fuel cell module AP1a, there are one fuel cell 7 in every 6 rows × 2 columns, 12 (fuel cells 7a to 7l). After being configured as a battery cell stack 8, twelve stacks of fuel cell stacks 8 a to 8 l are stored in the module container 4. Each fuel cell 7 in each stack 8 has a bottomed cylindrical shape, and is formed of a ceramic material to form a multilayer structure of an air electrode, an electrolyte (solid oxide), and a fuel electrode from the inside to the outside of the cylinder. ing. When air contacts the inner wall of the fuel cell 7, that is, the air electrode, and fuel gas contacts the outer wall, that is, the fuel electrode, O ²⁻ ions move in the cell to generate an electrochemical reaction, thereby generating an air electrode and a fuel electrode. A potential difference is generated between the two and power generation is performed. The electricity generated by the fuel battery cell 7 in this way is collected by a current collecting member (not shown) inside the module container 4 and sent to the inverter via the current collecting rods 5 and 5 ′. It is converted into an alternating current that can be used for the above. The structure, shape and number of the fuel cells 7 enclosed in each stack, the number and arrangement of the stacks constituting the module, and the like can be appropriately selected according to the desired power generation capacity and the like.

  As shown in FIGS. 1 and 2, the module container 4 is provided with an external reformer 1 at the center of the module wall 4a on the front side, and generally facing the external reformer 1 on the module wall 4c on the back side. The external reformer 1 'of the same type as the external reformer 1 is installed at the position where These external reformers 1 and 1 ′ have gas outlets 3 and 3 ′, respectively, and purify hydrogen, which is a reformed gas generated by the steam reforming reaction SR, in the polymer electrolyte fuel cell device AP2. It is sent out to the storage unit HB. Hydrogen from the external reformer 1, 1 'may be purified to high-purity hydrogen as necessary in the hydrogen purification storage unit HB, and then buffered. The hydrogen buffered in the hydrogen refining storage unit HB can be supplied to a reformed gas utilizing device such as the polymer electrolyte fuel cell module AP2a according to a request from the user. The external reformer 1 attached to the module container 4 of the solid oxide fuel cell apparatus AP1 according to the present embodiment is a single unit depending on conditions such as the amount of hydrogen desired on the reformed gas utilization device side. Or a plurality of external reformers 1 may be connected to separate reformed gas utilization devices, or one solid polymer type as in this embodiment. A plurality of external reformers 1, 1 ′ may be connected to the fuel cell device AP2. A plurality of external reformers 1 may be provided on one outer wall side surface of the module container 4.

  As shown in both FIG. 1 and FIG. 2, the external reformer 1 is attached to a substantially central portion of the outer surface of the module wall 4a and faces the external reformer 1 across the module wall 4a. There are four fuel cell stacks 8b to 8e. Among the fuel cells 7 included in these stacks, six fuel cells that are erected at positions corresponding to the external reformer 1 across the module wall 4a (fuel cells of the fuel cell stack 8c) 7b, fuel cell 7a, 7b of fuel cell stack 8d, fuel cell 7a, 7b of fuel cell stack 8c, and fuel cell 7a of fuel cell stack 8d) on the inner surface side of module wall 4a, An endothermic relaxation means 11 having an area covering the connection portion of the external reformer 1 to the module wall 4a is sandwiched. The endothermic relaxation means 11 used in the present embodiment can be a heat transfer means such as a copper plate having a thickness substantially equal to the distance between the fuel cell stacks 8b to 8e and the module wall 4a. The area, thickness, and material of the endothermic relaxation means 11 can be appropriately selected according to the endothermic state (position, temperature change amount, etc.) to be relaxed.

  Further, in the module container 4, an additional heat transfer plate 9b is provided between the fuel cell stacks 8b and 8c, and an additional heat transfer plate 9c is provided between the fuel cell stacks 8c and 8d, and the fuel cell stack 8d. And 8e are provided with an additional heat transfer plate 9d. These additional heat transfer plates 9 are also formed of a heat transfer material such as a copper plate, and each additional heat transfer plate 9 is connected to the heat absorption relaxation means 11 and passes through the heat absorption relaxation means 11. May be in contact with the module wall 4a. The function of the additional heat transfer plate 9 will be described in detail with reference to FIG.

  Similarly, the endothermic relaxation means 11 ′ is also sandwiched at a position facing the module wall 4 c of the external reformer 1 ′ attached to the substantially central portion of the module wall 4 c. An additional heat transfer plate 9h is provided between the fuel cell stacks 8h and 8i between the stacks inside the module container 4, and an additional heat transfer plate 9i is provided between the fuel cell stacks 8i and 8j. The additional heat transfer plate 9j is provided between the stacks 8j and 8k, and the additional heat transfer plate 9 is connected to the heat absorption mitigation means 11 ′ in the same manner as the heat absorption mitigation means 11 described above.

  Next, the mode of local endothermic state relaxation using the endothermic relaxation means 11 in the fuel cell system AP according to the embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a cross-sectional view schematically showing a III-III cross section in FIG. 2 of the solid oxide fuel cell device AP1 according to the present embodiment. In this figure, for the purpose of more simply explaining the state of relaxation of the local endothermic state, twelve fuel cells 7 to be shown in this section in the actually disposed fuel cell stacks 8d and 8j. Of these, only some of the fuel cells 7 (the fuel cells 7a, 7k in the fuel cell stack 8d and the fuel cells 7a, 7i, 7k in the fuel cell stack 8j) are displayed.

  In the sealed module container 4, among the fuel cells 7 that perform a power generation operation at a high temperature, the fuel cells 7 arranged on the outer side close to the module walls 4 a to 4 d of the module container 4 have the module walls 4 a to 4. Compared to the fuel battery cell 7 disposed closer to the center part farthest than 4d, a temperature drop is likely to occur due to heat radiation to the outside of the module container 4. For the same reason, the temperature of the upper and lower end portions of one fuel battery cell 7 tends to be lower than that of the central portion. That is, in the plurality of fuel cells 7 filling the module container 4, the temperature near the center is higher than the temperature at the outer end in any of the vertical direction, the horizontal direction, and the height direction. In FIG. 3, such a high-temperature portion HA is indicated by a broken line near the inner center of the module container 4.

  The additional heat transfer plates 9i and 9j described in FIG. 2 are divided into three strip-shaped copper plates as shown in FIG. It passes between the module walls 4a and 4c of the module container 4 through the high temperature part HA. Further, the additional heat transfer plates 9i and 9j pass through the endothermic relaxation means 11 and 11 ′ at their ends and come into contact with the module walls 4a and 4c and are held inside the module container 4. The additional heat transfer plate 9 arranged in this way is the fuel cell 7 including the high temperature part HA of the cell existing in the center of the module container 4 and the fuel which is likely to cause a temperature drop arranged near the module walls 4a and 4c. The heat transfer between the battery cells 7 is promoted, and the temperature distribution in the fuel cell 7 inside the module container 4 is made uniform. Thus, by effectively reducing the temperature variation among all the fuel cells 7, the power generation capability and durability of the solid oxide fuel cell device can be further improved.

  Here, as described above, the polymer electrolyte fuel cell device AP2 connected to the solid oxide fuel cell device AP1 is controlled separately from the solid oxide fuel cell device AP1. Basically, the solid oxide fuel cell device AP1 with poor load followability continues to generate power continuously with a substantially constant amount of power, whereas the solid polymer fuel cell device AP2 with high load followability It plays the role of instantaneously supplying the required amount of power according to the user's request. For example, when a request for increasing the amount of electric power used by a user is sent, first, a solid polymer of hydrogen that has been purified after being purified in the hydrogen purification storage unit HB in the polymer electrolyte fuel cell device AP2 The flow rate to the fuel cell module AP2a increases. However, when the demand for increasing the amount of power used by the user is continuous, or when a large amount of power is required even for a short time, only the hydrogen buffered in the hydrogen purification storage unit HB is used. It is impossible to meet the power generation requirement, and the power generation amount in the polymer electrolyte fuel cell device AP2 must be greatly increased. Therefore, when it is necessary to continuously or significantly increase the power generation amount itself in the polymer electrolyte fuel cell device AP2, it is necessary to increase the hydrogen supply amount in the external reformer 1. In this case, for the purpose of promoting the steam reforming reaction SR in the external reformer 1, it is necessary to increase the supply amount of the reformed gas AG to the external reformer 1.

  FIG. 4 is a schematic diagram showing a change in the endothermic state that can occur between the external reformer 1 and the module container 4 when the supply amount of the reformed gas AG to the external reformer 1 is increased. FIG. What is shown on the left side (a) of FIG. 4 is that the user is not instructed to increase the amount of power generation, or can respond to the increase command with hydrogen buffered in the hydrogen purification storage unit HB, etc. For this reason, it is in the endothermic state in the external reformer 1 in a state where the amount of the reformed gas is small. In this state, although the endothermic amount in the vicinity of the gas inlet 2 in the external reformer 1 is higher than the endothermic amount in the vicinity of the gas outlet 3, it cannot be said that the overall endothermic amount is large. On the other hand, what is shown on the right side (b) of FIG. 4 is that the amount of power generation in the polymer electrolyte fuel cell device AP2 is increasing in order to respond to the command to increase the amount of power generation by the user. For the reason, it is an endothermic state in the external reformer 1 with a large amount of inflow of the reformed gas. In this state, not only the supply amount of the reformed gas AG to the gas inlet 2 and the supply amount of hydrogen as reformed gas from the gas outlet 3 are increased, but also the gas inlet in the external reformer 1 It can be seen that both the endothermic amount near 2 and the endothermic amount near the gas outlet 3 are higher than the state shown in FIG. Then, the supply amount of the reformed gas AG is increased and the reforming reaction in the vicinity of the gas inlet 2 is further promoted, so that a local endothermic state is present in the periphery of the external reformer 1 around the gas inlet 2. It is also clear that can occur.

  As described above, since the external reformer 1 is attached to the module wall 4a of the module container 4, a plurality of fuel cells 7 disposed at positions facing the external reformer 1 with the module wall 4a interposed therebetween. The heat is taken away from the local endothermic state as shown in FIG. FIG. 3 shows a local heat absorption part LA resulting from this local heat absorption state. This local heat absorption part LA is generated in a region corresponding to a part of the plurality of fuel cells 7 arranged at a position facing the external reformer 1 with the module wall 4a of the module container 4 interposed therebetween. The temperature of the fuel battery cell 7 is significantly lower than the temperature of the fuel battery cell 7 arranged in a region other than the local heat absorbing portion LA. In addition, the local heat absorption part LA may be generated in one fuel cell 7 or may be generated only in a part of the connection part of the external reformer 1. However, in any of these cases, the temperature of the region corresponding to the local endothermic portion LA is lower than the temperature in the remaining region other than the region corresponding to the local endothermic portion LA in the module container 4. For this reason, the presence of the local endothermic portion LA due to the local endothermic state in the external reformer 1 is caused by a plurality of fuel cells contained in the module container 4 of the solid oxide fuel cell module AP1a. 7 can cause temperature unevenness.

  However, in the solid oxide fuel cell apparatus AP1 according to this embodiment, the endothermic relaxation means 11 having an area covering the mounting portion of the external reformer 1 is sandwiched at a position corresponding to the mounting position of the external reformer 1. In a part of the fuel cells 7 arranged at positions facing the external reformer 1 with the outer wall of the module container 4 interposed therebetween, a local heat absorption part due to a local heat absorption state of the external reformer 1 Even when LA occurs, the endothermic relaxation means 11 effectively propagates heat from any one of the fuel cells 7 arranged in a region other than the local endothermic portion LA to the local endothermic portion LA. Is possible. As a result, the endothermic (low temperature) state of the fuel cells 7 arranged in the local endothermic portion LA is alleviated, and the temperature unevenness in the module container 4 of the solid oxide fuel cell module AP1a as described above is eliminated. obtain. In addition, it is possible to make the power generation capacity uniform by eliminating the temperature unevenness, and the durability of the solid oxide fuel cell apparatus AP1 is also improved. Further, the heat from the fuel battery cells 7 other than the local heat absorption part LA is transferred to the fuel battery cells 7 arranged in the local heat absorption part LA, so that the local heat absorption requirement from the external reformer 1 is also improved. Therefore, the steam reforming reaction SR in the external reformer 1 can be further promoted. In addition, it is also possible to combine a plurality of heat transfer members having different heat transfer performances as the heat absorption mitigation unit 11 according to the present embodiment, and depending on the heat absorption state (position and temperature change amount, etc.) to be relaxed, You may use it combining a member suitably.

  Further, in the solid oxide fuel cell apparatus AP1 according to the present embodiment, the fuel cell 7 arranged at the center inside the module container 4 is in a higher temperature state. Then, the plurality of additional heat transfer plates 9 passing through the high temperature portion HA can transfer the heat generated in the fuel cell 7 in the central portion which is the hottest state inside the module container 4 to the additional heat transfer plate 9 and the heat absorption. It can be propagated to the local heat absorption part LA via the relaxation means 11. In this way, not only the local heat absorption (low temperature) state in the solid oxide fuel cell module AP1a can be further mitigated by propagating more heat to the vicinity of the local heat absorption part LA, but also in the module container 4 Thus, the durability of the solid oxide fuel cell device AP1 can be further improved. In this case, the heat required for the reforming reaction is transferred from the high temperature portion HA of the fuel cell 7 having the highest temperature to the fuel cell 7 disposed in the local heat absorbing portion LA. Further, the local endothermic demand is further improved, and the steam reforming reaction SR in the external reformer 1 can be further promoted.

  FIG. 5 is a simplified cross-sectional view of a solid oxide fuel cell apparatus AP1 according to a second embodiment of the present invention, and shows a mode of relaxation of a local endothermic state using a heat insulating material. . In this figure as well, as in FIG. 3, one of the 12 fuel cells 7 that can be actually arranged in the same plane for the purpose of more simply explaining the state of relaxation of the local endothermic state. Only the fuel cell 7 of the part is displayed.

  As in the previous embodiment, the external reformer 21 in this embodiment has a gas inlet 22 on the upper side and a gas outlet 23 on the lower side, and the gas to be reformed AG and water vapor are supplied to the gas inlet 22. Hydrogen supplied and generated by the steam reforming reaction SR is sent out from the gas outlet 23. As in the previous embodiment, since the steam reforming reaction SR performed in the external reformer 21 is an endothermic reaction, the external reformer 21 is a module container 4 of the solid oxide fuel cell module AP1a operating at a high temperature. It is attached to the wall.

  Similarly to the previous embodiment, also in the module container 4 of the solid oxide fuel cell module AP1a, the module container 4 centering around the vicinity of the gas inlet 22 of the external reformer 21 for the same reason as in the first embodiment. A local endothermic part LA may occur in the fuel cell 7. However, in the present embodiment, the external reformer 21 is a heat insulating material composed of two heat insulating materials having different heat insulating performances, that is, the heat insulating material 32 in the region near the gas inlet 22 and the heat insulating material 33 in the region near the gas outlet 23. The module 31 is attached to a substantially central portion of the module wall 4a via a material 31.

  As described above, in the solid oxide fuel cell module AP1a according to the present embodiment, the external reformer 21 includes the heat insulating material 31, so that the solid oxidation caused by the local endothermic reaction that can occur in the external reformer 21 is achieved. The influence of the temperature drop on the fuel cell 7 of the physical fuel cell module AP1a is suppressed. In particular, the heat insulating material 31 according to the present embodiment has a difference in heat insulating performance between the heat insulating material 32 and the heat insulating material 33 constituting the external heat reformer, and therefore an external reformer that easily generates an endothermic reaction according to the operation on the PEFC side. If the heat insulating performance of the heat insulating material 32 in the region near the gas inlet 22 of 21 is adjusted to be higher than that of the heat insulating material 33 in the region near the gas outlet 23 of the external reformer 21 where endothermic reaction is unlikely to occur, It is also possible to make the endothermic state transmitted from both heat insulating materials to the fuel cell 7 close to the same level and to make it uniform, thereby making it possible to localize the fuel cell 7 due to the local endothermic state of the external reformer 21. It is possible to significantly suppress the generation of the thermal endothermic portion LA and prevent the temperature decrease of the fuel cell 7. As described above, the solid oxide fuel cell device according to the present embodiment can suppress the generation of the local heat absorbing portion LA by a simple method of increasing the heat insulating ability of the heat insulating material 32 in the region near the gas inlet 22. It is possible to eliminate the temperature unevenness of the fuel cells 7 in the solid oxide fuel cell module AP1a, and improve the durability of the solid oxide fuel cell device AP1 as well as uniform power generation capacity. it can.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

1, 21: External reformer 2, 22: Gas inlet 3, 23: Gas outlet 4: Module container 4a-4d: Module wall 5: Current collecting rod 7: Fuel cell 8: Fuel cell stack 9: Additional transmission Heat plate 11: endothermic relaxation means 31, 32, 33: heat insulating material AP1: solid oxide fuel cell device AP1a: solid oxide fuel cell module AP2: solid polymer fuel cell device AP2a: solid polymer fuel cell Modules AP1v, AP2v: Inverter FG: Fuel gas FS: Fuel gas supply source OG: Oxidant gas OS: Oxidant gas supply source AG: Reformed gas AS: Reformed gas supply source HA: High temperature part HB: Hydrogen purification Storage part LA: Local heat absorption part

Claims (5)

A solid oxide fuel cell device comprising:
A plurality of cells that generate power using fuel gas and oxidant gas;
A module container containing the plurality of cells;
It is arranged on a part of the outer surface of the outer wall of the module container, and uses the heat generated at the time of power generation in the plurality of cells to modify the gas to be reformed by a reformed gas utilization device of another system by an endothermic reaction. With an external reformer that reforms into a quality gas,
A solid oxide fuel cell device having an endothermic mitigation means for mitigating a local endothermic state that may occur in a part of a cell disposed at a position facing the external reformer across the outer wall .   The endothermic relaxation means excludes a first region including cells arranged at a position facing the external reformer across the outer wall, and cells included in the first region from the plurality of cells. 2. The solid oxide fuel cell device according to claim 1, wherein the solid oxide fuel cell device is heat transfer means for thermally connecting the second region including the remaining cells.   3. The solid oxide fuel cell device according to claim 2, wherein the second region includes a cell that is disposed near an inner center of the module container and is in a high temperature state. 4. The endothermic relaxation means is a heat insulating means for insulating the inside and the outside of the module container,
The heat insulating means includes a first heat insulating portion provided corresponding to the first region, and a second heat insulating portion provided corresponding to the second region,
A difference is provided between the heat insulation performance in the first heat insulation portion and the heat insulation performance in the second heat insulation portion, and the heat absorption state propagating to the cell is made equal between the first heat insulation portion and the second heat insulation portion. The solid oxide fuel cell device according to claim 1.   The solid oxide fuel cell device according to claim 4, wherein the heat insulation performance of the first heat insulation portion is higher than the heat insulation performance of the second heat insulation portion.

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