JP2005078859A - Fuel cell system - Google Patents

Abstract

【Task】
Provided is a fuel cell system capable of reducing temperature distribution in a fuel cell while preheating fuel gas and air.
[Solution]
A fuel cell system including a plurality of fuel cell stacks 22 and coolers 7 and 8 is used. The plurality of fuel cell stacks 22 are provided in the container 26. The coolers 7 and 8 are provided between two adjacent fuel cell stacks 22. The coolers 7 and 8 are supplied with one of the fuel gas 1 and the oxidant gas 2 used in at least one of the plurality of fuel cell stacks 22 as a supply gas. Then, the temperature of the supplied gas is raised by the heat of the two adjacent fuel cell stacks 22. The coolers 7 and 8 may include a plurality of filling members in the flow path of the supply gas inside to improve the gas heat transfer coefficient.
[Selection] Figure 3

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system that improves the temperature distribution of the fuel cell.

  A fuel cell that is supplied with a fuel gas and an oxidant gas (eg, air) and generates electric power is known. It is known to generate power in the form of a fuel cell stack in which a plurality of fuel cells are stacked, or to generate power in the form of a fuel cell system in which a plurality of fuel cell stacks are combined.

  A solid oxide fuel cell (SOFC), which is one of the fuel cells, generates power at a high temperature of about 1000 ° C. The energy of the input fuel gas is converted into electricity and heat in the process of passing through the SOFC. Due to this heat generation, the temperature of the SOFC components (eg, power generation membrane, interconnector), fuel gas, and air becomes higher as they go downstream. Then, there is a difference in temperature between the inlet side and the outlet side of the fuel gas or air. In the case of SOFC, many of the members are ceramics. Therefore, the thermal stress resulting from the temperature difference between the inlet side and the outlet side may cause damage to each member of the SOFC.

  A technique for reducing the temperature distribution in a fuel cell is required. A technique for reducing the temperature difference between the inlet side and the outlet side of the fuel gas and air is desired. A technique for reducing the temperature distribution and improving the reliability without reducing the efficiency of the fuel cell is desired.

  As a related technique, Japanese Patent Application Publication No. 2002-516465 (PCT / DE99 / 01313) discloses a liquid-cooled fuel cell stack and a technique for cooling the fuel cell stack. The liquid-cooled fuel cell stack of this technology includes at least two fuel cell units. The sealing frame hermetically surrounds the intermediate chamber for accommodating the coolant between the separators of the fuel cell unit.

  Japanese Patent Publication No. 2000-504140 (PCT / DE96 / 02451) discloses a technology of a fluid-cooled fuel cell having a distribution passage. The fuel cell of this technology is a fuel cell including a fluid cooling means having a cathode, an electrolyte, and an anode. At least one distribution passage is provided for supplying medium to the cell surface, the distribution passage being in the cell surface such that the medium supply to the cell surface takes place along the edge of the cell surface from the distribution passage. Is provided.

  Japanese Unexamined Patent Application Publication No. 2003-109637 discloses a technique of a fuel cell cooling device and a control method for the fuel cell cooling device. The fuel cell cooling device of this technique includes a fuel cell, a cooling medium supply unit, a cooling medium cooling unit, a first temperature detection unit, a second temperature detection unit, and a control unit. The fuel cell is configured by sandwiching an electrolyte membrane between an oxidant electrode and a fuel electrode, and an oxidant gas is supplied to the oxidant electrode side and a fuel gas is supplied to the fuel electrode side to generate electric power. The cooling medium supply means supplies a cooling medium to the fuel cell. The cooling medium cooling means cools the cooling medium. The first temperature detection means detects an inflow cooling medium temperature that is the temperature of the cooling medium flowing into the fuel cell. The second temperature detection means detects an inflow cooling medium temperature that is a temperature of the cooling medium discharged from the fuel cell. The control means controls the power generation operation of the fuel cell and the cooling operation of the fuel cell by the cooling medium supply means and the cooling medium cooling means. In response to the temperature difference between the inflow cooling medium temperature detected by the first temperature detecting means and the exhaust cooling medium temperature detected by the second temperature detecting means becoming a predetermined value or more. Then, it is determined that an abnormality has occurred in the cooling medium supply means.

Special Table 2002-516465 gazette Special Table 2000-504140 JP 2003-109637 A

  Accordingly, an object of the present invention is to provide a fuel cell system capable of reducing the temperature distribution in the fuel cell.

  Another object of the present invention is to provide a fuel cell system capable of reducing a temperature difference between an inlet side and an outlet side of fuel gas and air in the fuel cell.

  Still another object of the present invention is to provide a fuel cell system capable of reducing the temperature difference between the inlet side and the outlet side of the fuel gas and air in the fuel cell while preheating the fuel gas and air. It is.

  Another object of the present invention is to provide a fuel cell system capable of reducing the temperature distribution and improving the reliability without reducing the efficiency of the fuel cell.

  Hereinafter, means for solving the problem will be described using the numbers and symbols used in the best mode for carrying out the invention. These numbers and symbols are added in parentheses in order to clarify the correspondence between the description of the claims and the best mode for carrying out the invention. However, these numbers and symbols should not be used for interpreting the technical scope of the invention described in the claims.

  Therefore, in order to solve the above problem, the fuel cell system of the present invention includes a plurality of fuel cell stacks (22) and coolers (7, 8). The plurality of fuel cell stacks (22) are provided in the container (26). The coolers (7, 8) are provided between two adjacent ones of the plurality of fuel cell stacks (22). The coolers (7, 8) are supplied with one of the fuel gas (1) and the oxidant gas (2) used in at least one of the plurality of fuel cell stacks (22) as a supply gas. Then, the temperature of the supply gas is raised by the heat of the two adjacent fuel cell stacks (22).

  By the coolers (7, 8) of the present invention, the fuel cell stack (22) can be cooled and the temperature rise can be suppressed. In addition, the temperature distribution of the fuel cell stack (22) can be reduced.

  In the fuel cell system, the cooler (7, 8) includes a plurality of tubes (44) arranged in parallel to each other so as to increase a heat input area.

  According to the present invention, heat input to the coolers (7, 8) is increased, and the fuel cell stack (22) can be cooled more efficiently and its temperature distribution can be reduced.

  In the fuel cell system described above, the coolers (7, 8) include a plurality of filling members (49) in the flow path of the supply gas inside to improve the gas heat transfer coefficient.

  According to the present invention, heat can be more efficiently absorbed by the supply gas in the flow path, the fuel cell stack (22) can be cooled more efficiently, and the temperature distribution can be reduced.

  In the fuel cell system, when the supply gas is the fuel gas (1), the plurality of filling members (49) include a reforming catalyst.

  According to the present invention, it is possible to cool the fuel cell stack (22) more efficiently and reduce the temperature distribution by the endothermic reaction during the reforming reaction.

  In the fuel cell system, the cooler (7) supplies the fuel gas (1) from a position corresponding to the high temperature portion in the two adjacent fuel cell stacks (22).

  According to the present invention, the place with the greatest endotherm (the place where the fuel gas (1) and the reforming catalyst first contact) comes to the position of the cooler (7) corresponding to the high temperature part of the fuel cell stack (22). Therefore, the high temperature part of a fuel cell stack (22) can be cooled more efficiently, and the temperature distribution can be reduced.

  In the fuel cell system described above, the coolers (7, 8) have a filling rate of the plurality of filling members (49) at positions corresponding to the high temperature portions in the two adjacent fuel cell stacks (22) so that the low temperature portion ( Higher than the filling rate at the position corresponding to C).

  According to the present invention, the cooler (7, 8) at the position corresponding to the high temperature part can cool the fuel cell stack (22) more efficiently and reduce the temperature distribution more accurately.

  In the fuel cell system, the coolers (7, 8) are provided at positions and sizes corresponding to the high temperature portions in the two adjacent fuel cell stacks (22).

  According to the present invention, the cooler (7, 8) at the position corresponding to the high temperature part can cool the fuel cell stack (22) more efficiently and reduce the temperature distribution more accurately.

  In the fuel cell system, the cooler (4a) includes a fuel heat exchange chamber (47) and an oxidant heat exchange chamber (48) that are provided adjacent to each other and perform heat exchange. The fuel heat exchange chamber (47) is supplied with the fuel gas (1) used in at least one of the plurality of fuel cell stacks (22) as the first supply gas. Then, the temperature of the first supply gas is raised by the heat of at least one of the two adjacent fuel cell stacks (22). The oxidant heat exchange chamber (48) is supplied with the oxidant gas (2) used in at least one of the plurality of fuel cell stacks (22) as the second supply gas. Then, the temperature of the second supply gas is raised by the heat of at least one of the two adjacent fuel cell stacks (22). At that time, heat exchange is performed so that the first supply gas and the second supply gas have the same temperature.

  According to the present invention, in addition to cooling the fuel cell stack (22) and reducing its temperature distribution, heat exchange that reduces the temperature difference between the fuel gas (1) and air (2) is more efficient. Can be done.

  In the fuel cell system described above, two adjacent fuel cells (22) are opposite to each other in the flowing direction of the supplied fuel gas (1) and oxidant gas (2).

  According to the present invention, the temperature distribution of the fuel cell stack (22) can be reduced.

  In the fuel cell system, each of the plurality of fuel cell stacks (22) includes a plurality of fuel cell units (31) and a gas flow layer (54). The plurality of fuel battery cells (31) are stacked and each has a flat plate shape. The gas flow layer (54) is provided between two adjacent fuel cells (31), and allows at least one of the fuel gas (1) and the oxidant gas (2) to flow therethrough.

  According to the present invention, the temperature distribution of the fuel cell stack (22) can be reduced.

  In the above fuel cell system, each of the plurality of fuel cell stacks (22) includes a plurality of fuel cell cells (31) and two current collector plates (32). The plurality of fuel battery cells (31) are stacked and each has a flat plate shape. The two current collecting plates (32) are provided at both ends of the plurality of fuel cells (31). The two current collecting plates (32) are provided thick so that the temperature distribution on the side in contact with the end of the plurality of fuel cells (31) is reduced.

  According to the present invention, the temperature distribution of the fuel cell stack (22) can be reduced.

  In order to solve the above problems, the fuel cell system of the present invention includes a container (26) and a plurality of fuel cell stacks (22) provided in the container (26). Adjacent two of the plurality of fuel cell stacks (22) are opposite in the flowing direction of the supplied fuel gas (1) and oxidant gas (2).

  According to the present invention, the temperature distribution of the fuel cell stack (22) can be reduced.

  In order to solve the above problems, the fuel cell system of the present invention includes a container (26) and a plurality of fuel cell stacks (22) provided in the container (26). Each of the plurality of fuel cell stacks (22) includes a plurality of stacked flat plate fuel cells (31), and two current collector plates (32) provided at both ends of the plurality of fuel cells (31). With. The two current collecting plates (32) are provided thick so that the temperature distribution on the side in contact with the end of the plurality of fuel cells (31) is reduced.

  According to the present invention, the temperature distribution of the fuel cell stack (22) can be reduced.

In order to solve the above problems, the fuel cell system of the present invention includes a container (26) and a plurality of fuel cell stacks (22) provided in the container (26). Each of the plurality of fuel cell stacks (22) is provided between two adjacent flat fuel cells (31) and a plurality of adjacent fuel cells (31). ) And an oxidant gas (2).

  According to the present invention, the temperature distribution of the fuel cell stack (22) can be reduced.

  In the fuel cell system, the fuel cell stack (22) is a solid oxide type.

  In the present invention, most of the members are made of ceramic, and the temperature distribution in one member, the temperature distribution in an integrated member, and the temperature difference between the supplied fuel gas and oxidant gas (2) are generated. This is particularly preferable for a solid oxide fuel cell stack (22) in which the influence of thermal stress is to be eliminated as much as possible.

  The present invention makes it possible to reduce the temperature distribution in the fuel cell while preheating the fuel gas and air.

  Hereinafter, embodiments of the fuel cell system of the present invention will be described with reference to the accompanying drawings.

  In this embodiment, a solid oxide fuel cell (SOFC) fuel cell system will be described as an example, but the present invention can be applied to a fuel cell system using other types of fuel cells. The fuel cell system 3 (described later) may be used as a fuel cell system.

(First embodiment)
First, a first embodiment of a fuel cell system of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a configuration of a first embodiment of a fuel cell system of the present invention. The fuel cell system includes a SOFC system main body 3, a heat exchanger 4, a combustor 5, a heat exchanger 6, a stack cooler 7, a stack cooler 8, and a fan 9. In the figure, the configuration related to power is omitted.

  The SOFC system body 3 is supplied with fuel gas 1 from the pipe 11-3 and air 2 from the pipe 13-4, and generates electric power. Thereafter, the spent fuel gas 1 is discharged from the pipe 12. The used air 2 is discharged from the pipe 14. The SOFC system main body 3 includes an SOFC module 21 (described later), a stack cooler 7 and a stack cooler 8. Here, the fuel gas 1 is exemplified by hydrocarbon gas such as hydrogen gas containing water vapor or methane gas containing water vapor. The air 2 may be other gas containing oxygen.

  The stack cooler 7 is supplied with the fuel gas 1 before being supplied to the SOFC system main body 3 from the pipe 11-1, and preheats the fuel gas 1 with the heat of the SOFC module 21. Then, the preheated fuel gas 1 is sent to the pipe 11-2. The SOFC module 21 is cooled by heat exchange at that time.

  Similarly, the stack cooler 8 is supplied with the air 2 before being supplied to the SOFC system main body 3 from the pipe 13-2, and preheats the air 2 with the heat of the SOFC module 21. And the preheated air 2 is sent out to the piping 13-3. The SOFC module 21 is cooled by heat exchange at that time.

  Only one of the stack cooler 7 and the stack cooler 8 may be provided.

  By using the stack cooler 7 and the stack cooler 8 as described above, the fuel gas 1 and the air 2 can be preheated and the SOFC system main body 3 can be cooled. That is, the thermal efficiency is improved.

  The heat exchanger 4 exchanges heat between the fuel gas 1 supplied from the pipe 11-2 and the air 2 supplied from the pipe 13-3. And the temperature difference between them is eliminated. After the heat exchange, the fuel gas 1 is supplied to the SOFC system main body 3 via the pipe 11-3 and the air 2 via the pipe 13-4.

  The combustor 5 receives the fuel gas 1 and the air 2 sent from the SOFC system main body 3 via the pipe 12 and the pipe 14, respectively. Then, they are mixed and burned and sent to the pipe 15-1 as high-temperature exhaust gas.

  The heat exchanger 6 preheats the air 2 supplied from the pipe 13-1 by heat exchange using the exhaust gas supplied from the pipe 15-1. The exhaust gas is sent to the pipe 15-2, and the air 2 is sent to the pipe 13-2.

  The fan 9 takes out part of the spent fuel gas 1 of the pipe 12 through the pipe 16-1 and returns it to the pipe 11-1 through the pipe 16-2 for recycling. This recycling improves the fuel utilization rate.

  Next, the SOFC module will be further described.

  FIG. 2 is a perspective view showing the configuration of the SOFC module. The SOFC module 21 is supplied with the fuel gas 1 and the air 2 and generates electric power. An SOFC stack 22, a manifold 23, and a manifold 24 are provided.

  The SOFC stack 22 is formed by stacking a plurality of SOFC cells (including separators), and includes current collecting plates for current collection on both sides. Fuel gas 1 and air 2 are supplied to generate electric power. In the drawing, the lower manifold 23 is supplied with the fuel gas 1 and sends it to the SOFC stack 22. The upper manifold 23 collects the fuel gas 1 used in the SOFC stack 22 and discharges it to the outside. In the figure, as indicated by arrows in the SOFC stack 22, the fuel gas 1 and the air 2 cross and flow with the SOFC cell interposed therebetween.

  Next, the SOFC system main body will be further described.

  FIG. 3 is a cross-sectional view showing the configuration of the SOFC system main body 3 in the first embodiment of the fuel cell system of the present invention. In this drawing, piping of fuel gas 1 or air 2 supplied to the manifold 23 and electrical wiring are omitted. The SPFC main body 3 includes a canister 26, a plurality of SOFC modules 21, and stack coolers 7 and 8.

  The canister 26 is a heat-insulating container that accommodates the plurality of SOFC modules 21 (including the SOFC stack 22) shown in FIG. The inside is at a high temperature of about 1000 ° C. due to heat generated by the SOFC stack 22 or the like.

  The SOFC stack 22 of the SOFC module 21 includes a plurality of stacked SOFC cells 31 and two current collecting plates 32 provided at both ends thereof. The current collecting plates 32 are electrically connected to the SOFC stacks 22 of the adjacent SOFC modules 21 by wires (not shown).

  In the figure, since either the stack cooler 7 or the stack cooler 8 may be used, two numbers are shown together. The stack cooler 7 is provided between two adjacent ones of the plurality of SOFC stacks 22. The fuel gas 1 supplied from the pipe 11-1 is heated by the heat (particularly, radiant heat) from the SOFC stacks 22 on both sides, and the temperature is raised. Then, the SOFC stacks 22 on both sides are cooled and cooled by applying heat. The heated and heated fuel gas 1 is sent to the pipe 11-2.

  Similarly, the stack cooler 8 is provided between two adjacent ones of the plurality of SOFC stacks 22. The air 2 supplied from the pipe 13-2 is heated by the heat (particularly radiant heat) from the SOFC stacks 22 on both sides, and the temperature is raised. Then, the SOFC stacks 22 on both sides are cooled and cooled by applying heat. The heated and heated air 2 is sent to the pipe 13-3.

  Next, the stack cooling unit will be further described.

  FIG. 4 is a perspective view showing the configuration of the stack cooling units 7 and 8 in the first embodiment of the fuel cell system of the present invention. The stack cooling units 7 and 8 include a cooling unit main body 42 and an attached pipe 43. The cooling unit main body 42 is a rectangular parallelepiped container (duct structure) formed of a heat-resistant metal (example: transition metal, heat-resistant steel) or ceramics (example: alumina, stabilized zirconia). The area of the surface viewed from the direction indicated by D1 is approximately equal to or slightly larger than the area of the SOFC stack 22 viewed from the direction of D2 in FIG. The stack cooling units 7 and 8 are installed at a position where the SOFC stack 22 overlaps with the SOFC stack 22 when viewed from the direction D2 in FIG. Thereby, the heat from the SOFC stack 22 can be received more reliably.

  In the stack cooling units 7 and 8, it is possible to provide a structure (eg, fins, baffle plates) conventionally used for increasing the efficiency of heat exchange.

  Next, the operation of the first embodiment of the fuel cell system of the present invention will be described.

  The fuel gas 1 passes through the pipe 11-1 and enters the SOFC system main body 3. Then, the SOFC system main body 3 enters the stack cooling unit 7. The SOFC stack 22 generates heat when generating power, and is about 1000 ° C. In the stack cooling unit 7, the fuel gas 1 receives heat (including radiant heat) from the SOFC stack 22, and is heated to raise the temperature. Thereafter, the heat exchanger 4 is reached via the pipe 11-2. In the heat exchanger 4, heat exchange with the air 2 is performed so as to eliminate a temperature difference with the air 2 as much as possible. Then, it enters the SOFC system main body 3 via the pipe 11-3. Then, it enters the SOFC module 21 of the SOFC system body 3 and is used for power generation in the SOFC stack 22. At that time, electricity and heat are generated. Thereafter, the spent fuel gas 1 is sent to the pipe 12. A part of the pipe 12 is recycled by the fan 9 to the pipe 11-1 via the pipe 16-1 and the pipe 16-2. Others are sent to the combustor 5.

  The air 2 passes through the pipe 13-1 and reaches the heat exchanger 6. In the heat exchanger 6, the temperature is raised by being heated by the high-temperature exhaust gas from the combustor 5. Then, it enters the SOFC system main body 3 via the pipe 13-2. Then, the SOFC system main body 3 enters the stack cooling unit 8. In the stack cooling unit 8, the air 2 receives heat (including radiant heat) from the SOFC stack 22, and is further heated to raise the temperature. Thereafter, the heat exchanger 4 is reached via the pipe 13-3. In the heat exchanger 4, heat exchange with the fuel gas 1 is performed so as to eliminate a temperature difference with the fuel gas 1 as much as possible. Then, it enters the SOFC system main body 3 via the pipe 13-4. Then, it enters the SOFC module 21 of the SOFC system body 3 and is used for power generation in the SOFC stack 22. At that time, electricity and heat are generated. Thereafter, the used air 2 is sent to the combustor 5 via the pipe 14.

  The fuel gas 1 and the air 2 in the combustor 5 are mixed and burned to become high-temperature exhaust gas. The hot exhaust gas is sent to the heat exchanger 6 via the pipe 15-1. The exhaust gas exchanges heat with the air 2 in the heat exchanger 6 and is cooled and cooled. Then, it is discharged via the pipe 15-2.

  At this time, since the heat of the SOFC stack 22 is removed by the stack cooling units 7 and 8, the SOFC stack 22 can be prevented from being abnormally heated. In heat exchange between the stack cooling units 7 and 8 and the SOFC stack 22, the amount of heat exchanged is larger as the temperature difference is larger. Therefore, it is possible to suppress the temperature distribution (temperature difference) on the surface of the SOFC stack viewed from the direction D2 in FIG. 3 by heat exchange with the stack cooling unit. Such a temperature difference is particularly effective in suppressing the temperature difference between the inlet side and the outlet side because the temperature difference between the inlet side and the outlet side in the SOFC stack 22 is large.

  According to the present invention, it is possible to reduce the temperature distribution in the SOFC while preheating the fuel gas 1 and the air 2.

  In the present invention, the structure of the stack cooler is not limited to the structure shown in FIG.

  FIG. 5 is a perspective view showing an application example of the configuration of the stack cooling units 7 and 8 in the first embodiment of the fuel cell system of the present invention. The stack cooling units 7 and 8 include a plurality of cooling unit main body tubes 44 and header piping 45. The cooling unit main body tube 44 is a tube formed of a heat-resistant metal (example: transition metal, heat-resistant steel) or ceramics (example: alumina, stabilized zirconia). The area formed by the plurality of cooling section main body tubes 44 as viewed from the direction indicated by D1 is approximately equal to or slightly larger than the area of the SOFC stack 22 as viewed from the direction D2 in FIG. The stack cooling units 7 and 8 are installed at a position where the SOFC stack 22 overlaps with the SOFC stack 22 when viewed from the direction D2 in FIG. Thereby, the heat from the SOFC stack 22 can be received more reliably.

  In addition, since the cooling unit main body tube 44 has a tube structure, the surface area is increased as compared with the case of FIG. That is, the heat input area from the SOFC stack 22 and the pipe inner area are increased. Thereby, heat exchange can be performed more efficiently. Furthermore, it is also possible to improve the heat transfer coefficient in the tube by inserting a spiral turbulence promoting body inside the cooling unit main body tube 44. In terms of strength, since it has a tube structure, the strength is improved and the heat stress resistance is improved. In addition, since only piping is arranged, processing is easy and cost can be reduced.

  In the present invention, a filling member may be introduced inside the stack cooler.

  FIG. 6 is a cross-sectional view showing an application example of the configuration of the SOFC system main body 3 in the first embodiment of the fuel cell system of the present invention. However, in this figure, the canister 26, the piping of the fuel gas 1 or air 2 supplied to the manifold 23, and the electrical wiring are omitted.

  This figure differs from FIG. 3 in that a filling member 49 is inserted inside the stack coolers 7 and 8. The gas flow path of the stack cooler is at a high temperature (1000 ° C. or its vicinity), and heat conduction by heat radiation is dominant. In such a situation, the filling member 49 capable of efficiently exchanging heat is preferably a material having a large surface area (eg, sphere, Raschig ring, porous body) and a high heat radiation rate. . Examples of such are ceramic balls, sintered metals, and ceramic fibers.

  By introducing the filling member 49, the equivalent gas heat transfer coefficient in the gas flow path of the stack cooler (gas heat transfer coefficient per unit area of the tube wall in consideration of the effect of the filling member) is improved. Thereby, heat exchange with the SOFC stack 22 can be performed efficiently. Therefore, the temperature rise and temperature distribution of the SOFC stack 22 can be further suppressed.

  In the present invention, the filling member 49 may contain a reforming catalyst. As such a reforming catalyst, when the fuel gas is a mixed gas of a hydrocarbon gas such as methane or propane and water vapor, a supported metal such as Ni, Ru or Rh and a carrier such as alumina, magnesia or zirconia. Is exemplified by a steam reforming catalyst configured in combination.

  The reforming reaction is an endothermic reaction, and the wall surface of the stack cooler is cooled by the endothermic reaction, so that the heat exchange between the SOFC stack 22 and the stack cooler 7 can be further promoted. In addition, the reforming of the fuel gas 1 can be performed simultaneously, and there is no need to provide a separate reformer outside.

  In the present invention, the filling member 49 need not be packed into the entire stack cooler. For example, the temperature distribution can be more accurately suppressed by providing more filling members 49 at positions corresponding to the high temperature portions of the SOFC stack 22.

  FIG. 7 is a cross-sectional view showing another application example of the configuration of the SOFC system main body 3 in the first embodiment of the fuel cell system of the present invention. However, in this figure, the canister 26, the piping of the fuel gas 1 or air 2 supplied to the manifold 23, and the electrical wiring are omitted.

  This figure differs from FIG. 6 in that a distribution is provided in the filling member 49 that fills the inside of the stack coolers 7 and 8. For the SOFC stack 22 having a temperature distribution in which the temperature on the gas downstream side increases, the filling rate of the filling member 49 in the portion corresponding to the gas downstream side is relatively high, and the filling rate of the filling member 49 in the portion corresponding to the region C is set. Is relatively low. When the filling rate is relatively high, more heat exchange is performed. On the other hand, when the filling rate is relatively low, less heat exchange is performed. Therefore, fine adjustment of cooling can be performed, and temperature distribution can be suppressed more accurately.

  In the present invention, the size (shape) of the stack cooler is not limited to FIGS. 4 and 5.

  FIG. 8 is a sectional view showing still another application example of the configuration of the SOFC system main body 3 in the first embodiment of the fuel cell system of the present invention. However, in this figure, the canister 26, the piping of the fuel gas 1 or air 2 supplied to the manifold 23, and the electrical wiring are omitted.

  This figure is different from FIG. 6 in that the size of the stack coolers 7 and 8 is changed. For the SOFC stack 22 having a temperature distribution in which the temperature on the gas downstream side increases, for example, the stack coolers 7 and 8 are provided at positions corresponding to portions corresponding to the gas downstream side. Thereby, heat exchange can be performed in a region where the temperature is relatively highest. Thereby, the temperature distribution in the SOFC stack 22 can be suppressed. In addition, the cost of the stack coolers 7 and 8 can be reduced.

  According to the present invention, it is possible to reduce the temperature distribution in the fuel cell, particularly the temperature difference between the inlet side and the outlet side of the fuel gas and air. In addition, fuel gas and air can be preheated at the same time. And it becomes possible to improve the efficiency and reliability as the whole system.

(Second Embodiment)
Next, a second embodiment of the fuel cell system of the present invention will be described with reference to the accompanying drawings.

  FIG. 9 is a diagram showing the configuration of the second embodiment of the fuel cell system of the present invention. The fuel cell system includes a SOFC system main body 3, a heat exchanger 4 a, a combustor 5, a heat exchanger 6, and a fan 9. In the figure, the configuration related to power is omitted.

  In this embodiment, instead of providing the stack coolers 7 and 8, the heat exchanger 4a is provided in the SOFC system body 3 and heat exchange with the SOFC stack 22 is different from the first embodiment.

  The SOFC system main body 3 is supplied with fuel gas 1 from the pipe 11-1 and air 2 from the pipe 13-2. Then, the heat exchanger 4a in the SOFC system main body 3 is configured such that the fuel gas 1 supplied from the pipe 11-1 and the air 2 supplied from the pipe 13-2 are changed in temperature difference between the fuel gas 1 and the air 2. Exchange heat to eliminate At the same time, heat exchange is performed among the fuel gas 1, the air 2, and the SOFC stack 22 so as to cool the SOFC stack 22. Thereafter, the SOFC module 21 of the SOFC system main body 3 is supplied with the fuel gas 1 via the pipe 11-2 and the air 2 via the pipe 13-3 to generate electric power.

  By using such a heat exchanger 4a, the fuel gas 1 and the air 2 can be preheated and the SOFC system main body 3 can be cooled. That is, the thermal efficiency is improved.

  Others (including the combustor 5, the heat exchanger 6, the fan 9, and the SOFC module 21 (FIG. 2)) are the same as those in the first embodiment except that the stack coolers 7 and 8 are not provided.

  Next, the SOFC system main body will be further described.

  FIG. 10 is a cross-sectional view showing the configuration of the SOFC system main body 3 in the second embodiment of the fuel cell system of the present invention. In this figure, the canister 26, the piping of the fuel gas 1 or air 2 supplied to the manifold 23, and the electrical wiring are omitted. The SPFC main body 3 includes a plurality of SOFC stacks 22 and a heat exchanger 4a.

  The SOFC stack 22 is the same as that in the first embodiment.

  The heat exchanger 4 a is provided between two adjacent ones of the plurality of SOFC stacks 22. A fuel heat exchange chamber 47 and an air heat exchange chamber 48 which are provided adjacent to each other and can exchange heat with each other are provided. On one SOFC stack 22 side, there is a fuel heat exchange chamber 47 for heat exchange with the SOFC stack 22. There is an air heat exchange chamber 48 on the other SOFC stack 22 side, and performs heat exchange with the SOFC stack 22.

  The fuel gas 1 supplied from the pipe 11-1 to the fuel heat exchange chamber 47 is heated by the heat (particularly radiant heat) from one SOFC stack 22 and heated. The SOFC stack 22 is cooled by applying heat, and the temperature is lowered. The fuel gas 1 to be heated and heated is simultaneously exchanged with the air 2 in the air heat exchange chamber 48 and sent to the pipe 11-2. And it is supplied to the manifold 23 of the SOFC module 21 without leaving the SOFC system main body 3 as it is.

  The air 2 supplied from the pipe 13-2 to the air heat exchange chamber 48 is heated by the heat (particularly radiant heat) from the other SOFC stack 22, and the temperature is raised. The SOFC stack 22 is cooled by applying heat, and the temperature is lowered. The air 2 to be heated and heated simultaneously exchanges heat with the fuel gas 1 in the fuel heat exchange chamber 47 and is sent to the pipe 13-3. Then, it is supplied to the manifold 24 of the SOFC module 21 without leaving the SOFC system main body 3 as it is.

  The heat exchanger 4a is a rectangular parallelepiped container (duct structure) formed of a heat-resistant metal (example: transition metal, heat-resistant steel) or ceramics (example: alumina, stabilized zirconia). The area of the surface viewed from the direction indicated by D3 is approximately equal to or slightly larger than the area of the SOFC stack 22. The heat exchanger 4a is installed at a position where the SOFC stack 22 overlaps with the SOFC stack 22 when viewed from the direction D3. Thereby, the heat from the SOFC stack 22 can be received more reliably.

  The shape is not limited to that shown in FIG. 10, and the fuel heat exchange chamber 47 and the air heat exchange chamber 48 that are capable of cooling the SOFC stack 22 and exchanging heat so as to eliminate a temperature difference from each other are provided. It only has to be prepared.

  Next, the operation of the second embodiment of the fuel cell system of the present invention will be described.

  The fuel gas 1 passes through the pipe 11-1 and enters the SOFC system main body 3. Then, the SOFC system main body 3 enters the fuel heat exchange chamber 47 of the heat exchanger 4a. The SOFC stack 22 generates heat when generating power, and is about 1000 ° C. In the fuel heat exchange chamber 47, the fuel gas 1 receives heat (including radiant heat) from the SOFC stack 22 and is heated to raise the temperature. At the same time, heat exchange with the air 2 in the air heat exchange chamber 48 is performed so as to eliminate the temperature difference with the air 2 as much as possible. After that, it enters the SOFC module 21 via the pipe 11-2 and is used for power generation in the SOFC stack 22. At that time, electricity and heat are generated. Thereafter, the spent fuel gas 1 is sent to the pipe 12. A part of the pipe 12 is recycled by the fan 9 to the pipe 11-1 via the pipe 16-1 and the pipe 16-2. Others are sent to the combustor 5.

  The air 2 passes through the pipe 13-1 and reaches the heat exchanger 6. In the heat exchanger 6, the temperature is raised by being heated by the high-temperature exhaust gas from the combustor 5. Then, it enters the SOFC system main body 3 via the pipe 13-2. Then, the SOFC system main body 3 enters the air heat exchange chamber 48 of the heat exchanger 4a. In the air heat exchange chamber 48, the air 2 receives heat (including radiant heat) from the SOFC stack 22 and is further heated to raise the temperature. At the same time, heat exchange with the fuel gas 1 in the fuel heat exchange chamber 47 is performed so as to eliminate the temperature difference with the fuel gas 1 as much as possible. After that, it enters the SOFC module 21 via the pipe 13-3 and is used for power generation in the SOFC stack 22. At that time, electricity and heat are generated. Thereafter, the used air 2 is sent to the combustor 5 via the pipe 14.

  The fuel gas 1 and the air 2 in the combustor 5 are mixed and burned to become high-temperature exhaust gas. The hot exhaust gas is sent to the heat exchanger 6 via the pipe 15-1. The exhaust gas exchanges heat with the air 2 in the heat exchanger 6 and is cooled and cooled. Then, it is discharged via the pipe 15-2.

  At this time, since the heat of the SOFC stack 22 is removed by the heat exchanger 4a, the SOFC stack 22 can be prevented from being abnormally heated. In heat exchange between the heat exchanger 4a and the SOFC stack 22, the amount of heat exchanged is larger as the temperature difference is larger. Therefore, the temperature distribution (temperature difference) on the surface of the SOFC stack as viewed from the direction D3 in FIG. 10 can be suppressed by heat exchange with the stack cooling unit. Such a temperature difference is particularly effective in suppressing the temperature difference between the inlet side and the outlet side because the temperature difference between the inlet side and the outlet side in the SOFC stack 22 is large.

  According to the present invention, an effect similar to that of the first embodiment can be obtained. In addition, the application example of the first embodiment described with reference to FIGS. 6, 7, and 8 is within a range where no problem occurs in the temperature of the fuel gas 1 and the air 2 that are finally introduced into the SOFC module 21. It is possible to apply similarly.

  Furthermore, since the heat exchanger 4a is provided in the SOFC system main body 3, a temperature difference between the fuel gas 1 and the air 2 hardly occurs after the heat exchanger 4a. Therefore, the thermal stress due to the temperature difference between the fuel gas 1 and the air 2 on the inlet side of the SOFC stack 22 can be eliminated. And compared with the case of 1st Embodiment, it becomes possible to make an apparatus compact.

  In the present invention, the current collector plate 32 of the SOFC stack 22 of the SOFC module 21 may be thicker. This is shown in FIG. That is, FIG. 11 is a sectional view showing an application example of the configuration of the SOFC system main body 3 in the second embodiment of the fuel cell system of the present invention. In this case, the temperature distribution of the SOFC stack 22 can be relaxed by the heat conduction of the current collector plate 32, and the temperature of the SOFC stack 22 can be equalized. This is effective even if performed alone, but more effective and more preferable when performed in combination with at least one of the first and second embodiments.

  In the present invention, the flows of the fuel gas 1 and the air 2 in the plurality of SOFC modules 21 are all in the same direction. However, it is not always necessary to do so, and the flow of the fuel gas 1 and the air 2 may be reversed between two adjacent SOFC modules 21. This is shown in FIG. That is, FIG. 12 is a sectional view showing another application example of the configuration of the SOFC system main body 3 in the second embodiment of the fuel cell system of the present invention. The flow of the fuel gas 1 and the air 2 exemplified by arrows are in opposite directions in the adjacent SOFC modules 21. In this case, the temperature distribution in the SOFC stack 22 is reversed between adjacent SOFC modules 21. That is, the temperature distribution can be canceled as a whole of the SOFC system main body 3. This may be performed alone or in combination with at least one of the first and second embodiments. It is also possible to have the configuration of FIG. In that case, the effect of reducing the temperature distribution is further increased.

  In the present invention, the SOFC stack 22 has a structure in which a plurality of SOFC cells 31 are stacked. However, this is not always necessary, and a pseudo SOFC cell 31 that allows only gas to pass therethrough may be provided in the middle of the stacked SOFC cells 31. This is shown in FIG. That is, FIG. 13 is a sectional view showing still another application example of the configuration of the SOFC system main body 3 in the second embodiment of the fuel cell system of the invention. The SOFC cell 31 includes an interconnector 51 and a power generation film 52 (details of this structure are described in, for example, Japanese Patent Application Laid-Open Nos. 2002-141081 and 2002-141097). In this case, a gas flow layer 54 in which the power generation film 52 is replaced with a metal film is placed in the middle of the stacked SOFC cells 31. In this way, it is possible to use the fuel gas 1 and the air 2 as a cooling gas instead of power generation while securing a current path. Then, the SOFC stack 22 can be directly cooled. In the figure, the gas circulation layer 54 for one layer is provided, but the number is not limited to this. This is effective even if performed alone, but more effective and more preferable when performed in combination with at least one of the first and second embodiments. It is also possible to have the configuration of FIG. 11 or FIG. In that case, the effect of reducing the temperature distribution is further increased.

  According to the present invention, the temperature distribution in the fuel cell, in particular, the temperature difference between the inlet side and the outlet side of the fuel gas and air in the fuel cell can be reduced. In addition, it can be carried out while preheating the fuel gas and air. Furthermore, it is possible to reduce the temperature distribution and improve the reliability without reducing the efficiency of the fuel cell.

  Since most members of a solid oxide fuel cell (SOFC) are made of ceramic, temperature distribution in one member, temperature distribution in an integrated member, supplied fuel gas and oxidant gas (2 ) And is susceptible to thermal stresses caused by various causes such as temperature differences between them. However, according to the present invention, these causes are eliminated, the temperature distribution is suppressed, and it is possible to eliminate a decrease in reliability due to thermal stress.

  Such a technique can also be applied to water electrolysis, which is a reverse reaction of a fuel cell, and a hydrogen production apparatus to which it is applied.

FIG. 1 is a diagram showing a configuration of a first embodiment of a fuel cell system of the present invention. FIG. 2 is a perspective view showing the configuration of the SOFC module. FIG. 3 is a cross-sectional view showing the configuration of the SOFC system main body in the first embodiment of the fuel cell system of the present invention. FIG. 4 is a perspective view showing the configuration of the stack cooling section in the first embodiment of the fuel cell system of the present invention. FIG. 5 is a perspective view showing an application example of the configuration of the stack cooling unit in the first embodiment of the fuel cell system of the present invention. FIG. 6 is a cross-sectional view showing an application example of the configuration of the SOFC system main body in the first embodiment of the fuel cell system of the present invention. FIG. 7 is a sectional view showing another application example of the configuration of the SOFC system main body in the first embodiment of the fuel cell system of the present invention. FIG. 8 is a cross-sectional view showing still another application example of the configuration of the SOFC system main body in the first embodiment of the fuel cell system of the present invention. FIG. 9 is a diagram showing the configuration of the second embodiment of the fuel cell system of the present invention. FIG. 10 is a cross-sectional view showing the configuration of the SOFC system main body in the second embodiment of the fuel cell system of the present invention. FIG. 11 is a cross-sectional view showing an application example of the configuration of the SOFC system main body in the second embodiment of the fuel cell system of the present invention. FIG. 12 is a sectional view showing another application example of the configuration of the SOFC system main body in the second embodiment of the fuel cell system of the present invention. FIG. 13 is a sectional view showing still another application example of the configuration of the SOFC system main body in the second embodiment of the fuel cell system of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel gas 2 Air 3 SOFC system main body 4, 4a Heat exchanger 5 Combustor 6 Heat exchanger 7, 8 Stack cooler 9 Fan 11-1 to 11-3, 12, 13-1 to 13-4,
14, 15-1 to 15-2, 16-1 to 16-2 Piping 21 SOFC module 22 SOFC stack 23, 24 Manifold 26 Canister 31 SOFC cell 32 Current collector plate 42 Cooling unit body 43 Attached piping 44 Cooling unit body tube 45 Header piping 47 Heat exchange chamber for fuel 48 Heat exchange chamber for air 49 Filling member 51 Interconnector 52 Power generation membrane 54 Gas distribution layer

Claims (15)

A plurality of fuel cell stacks provided in the container;
A cooler provided between two adjacent ones of the plurality of fuel cell stacks,
The cooler is supplied with any one of a fuel gas and an oxidant gas used in at least one of the plurality of fuel cell stacks as a supply gas, and is supplied with heat of the two adjacent fuel cell stacks. A fuel cell system that heats the gas and cools the stack. The fuel cell system according to claim 1, wherein
The cooler includes a plurality of tubes arranged in parallel to each other so as to increase a heat input area. The fuel cell system according to claim 1 or 2,
The said cooler is provided with a some filling member in the flow path of the said supply gas inside so that a gas heat transfer rate may be improved. Fuel cell system. The fuel cell system according to claim 3, wherein
When the supply gas is the fuel gas, the plurality of filling members include a reforming catalyst. The fuel cell system according to claim 4, wherein
The said cooler supplies the said fuel gas from the position corresponding to the high temperature part in the said two adjacent said fuel cell stacks Fuel cell system. The fuel cell system according to any one of claims 1 to 5,
In the cooler, the filling rate of the plurality of filling members at a position corresponding to a high temperature portion in the two adjacent fuel cell stacks is higher than a filling rate at a position corresponding to a low temperature portion. The fuel cell system according to any one of claims 1 to 5,
The said cooler is provided in the position and magnitude | size corresponding to the high temperature part in the said two said adjacent fuel cell stacks Fuel cell system. The fuel cell system according to any one of claims 1 to 5,
The cooler includes a heat exchange chamber for fuel and a heat exchange chamber for oxidant that are provided adjacent to each other and perform heat exchange,
The fuel heat exchange chamber is supplied with the fuel gas used in at least one of the plurality of fuel cell stacks as a first supply gas, and heat of at least one of the two adjacent fuel cell stacks. To raise the temperature of the first supply gas,
The oxidant heat exchange chamber is supplied with the oxidant gas used in at least one of the plurality of fuel cell stacks as a second supply gas, and at least the other of the two adjacent fuel cell stacks. The temperature of the second supply gas is increased with one heat of
A fuel cell system that performs heat exchange so that the first supply gas and the second supply gas have the same temperature. The fuel cell system according to any one of claims 1 to 8,
Two adjacent fuel cells in the plurality of fuel cell stacks are opposite to each other in the flow direction of the supplied fuel gas and oxidant gas. The fuel cell system according to any one of claims 1 to 9,
Each of the plurality of fuel cell stacks is
A plurality of stacked fuel cells, and
A fuel cell system, comprising: a gas flow layer provided between two adjacent fuel cell units and flowing at least one of a fuel gas and an oxidant gas. The fuel cell system according to any one of claims 1 to 10,
Each of the plurality of fuel cell stacks is
A plurality of stacked fuel cells, and
Two current collector plates provided at both ends of the plurality of fuel cells,
The two current collector plates are provided thick so that the temperature distribution on the side in contact with the end of the plurality of fuel cells is reduced. A container,
A plurality of fuel cell stacks provided in the container,
Two adjacent fuel cells in the plurality of fuel cell stacks are opposite to each other in the flow direction of the supplied fuel gas and oxidant gas. A container,
A plurality of fuel cell stacks provided in the container;
Comprising
Each of the plurality of fuel cell stacks is
A plurality of stacked fuel cells, and
Two current collector plates provided at both ends of the plurality of fuel cells,
The two current collector plates are provided thick so that the temperature distribution on the side in contact with the end of the plurality of fuel cells is reduced. A container,
A plurality of fuel cell stacks provided in the container;
Comprising
Each of the plurality of fuel cell stacks is
A plurality of stacked fuel cells, and
A fuel cell system, comprising: a gas flow layer provided between two adjacent fuel cell units and flowing at least one of a fuel gas and an oxidant gas. The fuel cell system according to any one of claims 1 to 14,
The fuel cell stack is a solid oxide type fuel cell system.

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