JP2012003941A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell that prevents a short circuit formed between a fuel cell stack and an auxiliary unit to have high reliability, and is made high in thermal efficiency and low-cost.SOLUTION: A fuel cell 1 includes a fuel cell stack 10 and an auxiliary unit 20. The fuel cell stack 10 is formed by stacking a plurality of power generation cells 11, and generates electric power through power generation reaction. The auxiliary unit 20 has at least one of respective functions of preheating raw materials including an oxidizer and fuel, burning a residual fuel gas after power generation, vaporizing a liquid raw material, and reforming the raw materials. The auxiliary unit 20 is arranged nearby a side face 14 of the fuel cell stack 10. The parts of insulating members 53, 58 constituting the fuel cell stack 10 are provided with protrusion parts 91 protruding from a side face 14 of the fuel cell stack 10 toward the auxiliary unit 20.

Description

  The present invention relates to a fuel cell including a fuel cell stack that generates electric power by a power generation reaction, and an auxiliary device that is disposed close to a side surface of the fuel cell stack.

  Conventionally, as a fuel cell, for example, a solid oxide fuel cell (SOFC) including a solid electrolyte layer (solid oxide layer) is known. This SOFC includes a power generation cell in which a fuel electrode layer in contact with a fuel gas and an air electrode layer in contact with an oxidant gas are disposed on both sides of the solid electrolyte layer. In recent years, in order to improve performance, various SOFCs including a fuel cell stack in which a plurality of power generation cells are stacked have been proposed.

  Since the SOFC is a high-temperature fuel cell, the power generation reaction between the fuel gas and the oxidant gas occurs only when the fuel gas and the oxidant gas are heated to the operating temperature (for example, 500 ° C. to 1000 ° C.). Power can be generated. Therefore, for example, a preheater (auxiliary device) that preheats fuel gas and oxidant gas using heat of the fuel cell stack (Joule heat or the like) is arranged on the side surface of the fuel cell stack. (For example, refer to Patent Document 1).

US Pat. No. 7,374,834 (FIG. 5 etc.)

  By the way, such a preheater receives more heat from the fuel cell stack as it comes closer to the side surface of the fuel cell stack, so that the gas can be preheated efficiently. However, if the preheater is too close, the preheater or the fuel cell stack itself may be deformed due to repeated thermal cycles. May decrease. Therefore, in the prior art described in Patent Document 1, an insulating insert (49) is disposed between the fuel cell stack (51) and the gas flow panel (55) as a preheater.

  However, in order to arrange the insulating insert described above between the preheater and the fuel cell stack, a fixing means such as a bolt is usually indispensable. As a result, since inserts and fixing means are required at the time of manufacturing the fuel cell, an increase in the number of parts and man-hours is unavoidable, leading to an increase in manufacturing cost.

  Further, when the insulating insert described above is arranged between the preheater and the fuel cell stack, what is expected of the preheater, specifically, it receives a lot of heat from the fuel cell stack and efficiently releases the gas. There is a problem that there is a conflict with preheating.

  The present invention has been made in view of the above problems, and its purpose is to prevent a short circuit occurring between the fuel cell stack and the auxiliary device, to increase reliability, and to achieve high thermal efficiency. An object of the present invention is to provide a fuel cell capable of reducing the cost.

  As means (means 1) for solving the above-mentioned problem, a plurality of power generation cells having an electrolyte layer, a fuel electrode layer disposed on both sides thereof and in contact with fuel gas and an air electrode layer in contact with oxidant gas are stacked. A fuel cell stack that generates power by a power generation reaction, and in the power generation reaction in the fuel cell stack, preheating of a raw material containing an oxidant and fuel, combustion of residual fuel gas after power generation, vaporization of a liquid raw material, and One of insulating members constituting the fuel cell stack in a fuel cell having at least one of the reforming functions and including an auxiliary device disposed in proximity to a side surface of the fuel cell stack There is a fuel cell characterized in that it has an overhanging portion that protrudes from the side surface of the fuel cell stack toward the auxiliary device.

  According to the invention described in the means 1, the fuel cell includes the overhanging portion formed by projecting a part of the insulating member constituting the fuel cell stack from the side surface of the fuel cell stack toward the auxiliary device. As a result, the distance between the fuel cell stack and the auxiliary device is kept constant via the overhanging portion, so that contact between the two is avoided. Therefore, a short circuit that occurs between the fuel cell stack and the auxiliary device is prevented, so that the reliability of the fuel cell can be increased. In addition, since a part of the insulating member constituting the fuel cell stack becomes the overhanging portion, the overhanging portion is integrated with the fuel cell stack. Therefore, there is no need to provide a fixing means for fixing the overhang portion to the fuel cell stack. Therefore, the number of parts of the fuel cell is reduced, and the number of man-hours at the time of manufacture is reduced, so that the cost of the fuel cell can be reduced.

  In addition, in order to reliably conduct the heat from the fuel cell stack to the auxiliary device, the space between the fuel cell stack and the auxiliary device is insulated with a minimum of parts (overhangs), and the remaining space is shielded. Therefore, it is possible to efficiently raise the temperature of the auxiliary device (for example, when the auxiliary device is a preheater, the gas in the preheater). Furthermore, if the minimum parts that insulate the fuel cell stack and the auxiliary device are set to substantially the same temperature as the fuel cell stack, the auxiliary device can be heated more efficiently.

Here, as the fuel cell, a solid oxide fuel cell (SOFC) using a ZrO ₂ ceramic or the like as an electrolyte, a solid polymer fuel cell (PEFC) using a polymer electrolyte membrane as an electrolyte, Li-Na / K Examples thereof include a molten carbonate fuel cell (MCFC) using a system carbonate as an electrolyte, and a phosphoric acid fuel cell (PAFC) using phosphoric acid as an electrolyte. Note that the operating temperature of the fuel cell (that is, the temperature at which ions can move in the electrolyte) differs for each type of fuel cell. Specifically, the operating temperature of SOFC is about 700 ° C. to 1000 ° C., the operating temperature of PEFC is about room temperature to about 90 ° C., the operating temperature of MCFC is about 650 ° C. to 700 ° C., and the operating temperature of PAFC is 150 ° C. to 200 ° C. It is about ℃.

  The fuel cell stack constituting the fuel cell is formed by stacking a plurality of power generation cells. The electrolyte layer constituting the power generation cell has a property (ion conductivity) in which at least one of the fuel gas in contact with the fuel electrode layer and the oxidant gas in contact with the air electrode layer move as ions. Examples of ions that move in the electrolyte layer include oxygen ions and hydrogen ions.

When the fuel cell is SOFC, examples of the material for forming the electrolyte layer (solid oxide layer) include ZrO ₂ ceramic, LaGaO ₃ ceramic, BaCeO ₃ ceramic, SrCeO ₃ ceramic, SrZrO ₃ ceramic, and CaZrO _3. There are ceramics.

Further, the fuel electrode layer constituting the power generation cell is in contact with the fuel gas serving as the reducing agent, and functions as a negative electrode in the power generation cell. Here, as the material for forming the fuel electrode layer, for example, ZrO ₂ ceramics stabilized by rare earth elements (Sc, Y, etc.), CeO ₂ ceramics doped with rare earth elements (Sm, Gd, etc.), etc. Among them, a mixture of at least one ceramic material and a metal (Ni, Fe, etc.) can be mentioned. Examples of the material for forming the fuel electrode layer include metal materials such as Pt, Au, Ag, Pd, Ir, Ru, Rh, Ni, and Fe, and alloys thereof. In addition, you may select the mixture (cermet etc.) of a metal material (or alloy) and a ceramic material. Furthermore, a mixture of an oxide of a metal material (such as Ni or Fe) and a ceramic material may be selected.

  Moreover, as fuel gas, hydrogen gas, hydrocarbon gas, the mixed gas of hydrogen gas and hydrocarbon gas, etc. are mentioned, for example. When the hydrocarbon gas is selected as the fuel gas, the type of the hydrocarbon gas is not particularly limited, but is preferably natural gas, naphtha, coal gasification gas, or the like. It is obtained by mixing water vapor with fuel gas obtained by passing gas (hydrogen gas, hydrocarbon gas, mixed gas) in water and humidifying it, or gas (hydrogen gas, hydrocarbon gas, mixed gas). The fuel gas to be used may be selected. Further, only one type of fuel gas may be used, or a plurality of types of fuel gas may be used in combination. Further, the fuel gas may contain an inert gas such as nitrogen or argon. Moreover, what vaporized the liquid raw material can be used as fuel gas, or hydrogen gas produced by reforming a gas other than hydrogen gas can be used as fuel gas.

The air electrode layer constituting the power generation cell is in contact with an oxidant gas serving as an oxidant and functions as a positive electrode in the power generation cell. Here, examples of the material for forming the air electrode layer include metal materials, metal oxides, metal composite oxides, and the like. Preferable examples of the metal material include Pt, Au, Ag, Pd, Ir, Ru, Rh, etc., and alloys thereof. Preferable examples of the metal oxide include La, Sr, Ce, Co, Mn, Fe oxide (La ₂ O ₃ , SrO, Ce ₂ O ₃ , Co ₂ O ₃ , MnO ₂ , FeO), etc. There is. Preferable examples of metal composite oxides include, for example, composite oxides containing La, Pr, Sm, Sr, Ba, Co, Fe, and Mn (La _1-x Sr _x CoO ₃ -based composite oxide, La _{1 -x} Sr _x FeO _3-based composite _{oxide, La 1-x Sr x Co} 1-y Fe y O 3 composite _{oxide, La 1-x Sr x MnO} 3 composite _oxide, Pr _1-x Ba _x CoO ₃ type composite oxide, Sm _1-x Sr _x CoO ₃ type composite oxide) and the like.

  Examples of the oxidant gas include a mixed gas of oxygen and another gas. This mixed gas may contain an inert gas such as nitrogen or argon. The mixed gas is preferably safe and inexpensive air.

  Furthermore, the insulating member constituting the fuel cell stack can be appropriately selected in consideration of the insulating property, heat resistance, sealing property, and the like, and examples of the forming material include a ceramic material. Preferable examples of the ceramic material include low-temperature fired materials such as mica ceramic, alumina, glass ceramic, and crystallized glass, aluminum nitride, silicon carbide, and silicon nitride.

  The insulating member constituting the fuel cell stack is preferably an insulating frame that is disposed and stacked in a plurality of power generation cells and also serves as a seal member. In this way, it is not necessary to provide the sealing member separately from the insulating member. As a result, the number of parts of the fuel cell is further reduced, so that the cost of the fuel cell can be further reduced.

  In addition, as an auxiliary device which comprises a fuel cell, the preheater (heat exchanger) which has the function of the preheating of the raw material containing an oxidizing agent and a fuel, the heat generator which has the function of the combustion of the residual fuel gas after electric power generation, liquid raw material And a reformer having a function of reforming a raw material.

  In addition, the fuel cell includes an overhang portion formed by projecting a part of the insulating member constituting the fuel cell stack from the side surface of the fuel cell stack toward the auxiliary device. In addition, it is preferable that the front-end | tip of an overhang | projection part is contact | abutted to the auxiliary device, and it is preferable to fit and fix to the recessed part provided in the auxiliary device especially. In this way, the distance between the fuel cell stack and the auxiliary device can be easily kept constant, so that the reliability of the fuel cell can be reliably increased.

  Moreover, it is preferable that the overhang part is formed with an opening part that communicates both side surfaces in the stacking direction. If it does in this way, when starting up a fuel cell stack with a starting burner at the time of starting of a fuel cell, for example, it can set so that hot burner exhaust gas may pass through an opening. That is, since the high-temperature burner exhaust gas passes through the vicinity of the fuel cell stack, the fuel cell stack is quickly warmed by the burner exhaust gas that has passed through the opening to reach the operating temperature. For this reason, the start-up time of the fuel cell can be shortened.

  In addition, it is preferable that the ratio for which an opening part accounts in a protrusion part is 10% or more and 90% or less. If the ratio of the opening is less than 10%, the above-described high-temperature burner exhaust gas is difficult to pass through the opening, so that the fuel cell stack is not easily warmed by the burner exhaust gas that has passed through the opening. The startup time cannot be shortened. On the other hand, when the ratio occupied by the opening is larger than 90%, the strength of the overhanging portion is reduced and the overhanging portion is likely to be deformed, so that the distance between the fuel cell stack and the auxiliary device cannot be kept constant. Note that only one opening may be formed for one overhang, or a plurality of openings may be formed for one overhang.

  As another means (means 2) for solving the above-mentioned problem, a plurality of power generation cells having an electrolyte layer, a fuel electrode layer disposed on both sides thereof and in contact with the fuel gas, and an air electrode layer in contact with the oxidant gas are stacked. A fuel cell stack that generates power by a power generation reaction, and in the power generation reaction in the fuel cell stack, preheating of a raw material containing an oxidant and fuel, combustion of residual fuel gas after power generation, vaporization of a liquid raw material, and A fuel cell having at least one function among the reforming functions of the raw material and provided with an auxiliary device disposed in the vicinity of the side surface of the fuel cell stack, the conductivity constituting the fuel cell stack A protruding portion is formed by protruding a part of the metal member from the side surface of the fuel cell stack toward the auxiliary device, and an insulating coating is integrally formed on the protruding portion. There is a fuel cell.

  According to the invention described in the means 2, the fuel cell includes the overhanging portion formed by projecting a part of the conductive metal member constituting the fuel cell stack from the side surface of the fuel cell stack toward the auxiliary device. As a result, the distance between the fuel cell stack and the auxiliary device is kept constant via the overhanging portion, so that contact between the two is avoided. Further, since the insulating coating is integrally formed on the overhanging portion that contacts both the fuel cell stack and the auxiliary device, insulation between the fuel cell stack and the auxiliary device is ensured. Therefore, a short circuit that occurs between the fuel cell stack and the auxiliary device is prevented, so that the reliability of the fuel cell can be increased. In addition, since a part of the conductive metal member constituting the fuel cell stack becomes the overhanging portion, the overhanging portion is integrated with the fuel cell stack. Therefore, there is no need to provide a fixing means for fixing the overhang portion to the fuel cell stack. Therefore, the number of parts of the fuel cell is reduced, and the number of man-hours at the time of manufacture is reduced, so that the cost of the fuel cell can be reduced.

  In addition, as a forming material of the insulating film integrally formed on the projecting portion, for example, a ceramic material or the like can be given. Preferable examples of the ceramic material include mica ceramic, alumina, zirconia, glass ceramic, crystallized glass, aluminum nitride, silicon carbide, and silicon nitride. The insulating film is preferably an oxide ceramic, that is, a heat-resistant insulating film mainly composed of alumina, zirconia, or the like. In this way, even if the temperature of the overhanging portion rises, the insulating coating keeps covering the overhanging portion without melting, so that a short circuit occurring between the fuel stack and the auxiliary device is reliably prevented, The reliability of the fuel cell is further improved. In addition, as a method of integrally forming the insulating coating on the overhanging portion, firing after completion of thermal spraying or spray coating can be exemplified.

The disassembled perspective view which shows the fuel cell in this embodiment. 1 is a schematic plan view showing a fuel cell. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. The disassembled perspective view which shows a power generation cell. The schematic sectional drawing which shows a power generation cell. The block diagram which shows the system structure of a fuel cell. The schematic plan view which shows the upper side insulation frame in other embodiment. The schematic plan view which shows the insulation frame in other embodiment. The schematic plan view which shows the insulation frame in other embodiment. The principal part sectional drawing which shows the fuel cell in other embodiment. The principal part sectional drawing which shows the fuel cell in other embodiment. The schematic perspective view which shows the fuel cell stack in other embodiment. The schematic plan view which shows the fuel cell in other embodiment. The schematic plan view which shows the fuel cell in other embodiment. The schematic sectional drawing which shows the fuel cell in other embodiment. The schematic sectional drawing which shows the fuel cell in other embodiment. The schematic plan view which shows the fuel cell in other embodiment.

  Hereinafter, an embodiment embodying the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the fuel cell 1 of the present embodiment is a solid oxide fuel cell (SOFC). The fuel cell 1 includes a fuel cell stack 10 that generates electric power by a power generation reaction, a preheater 20 (heat exchanger) that is an auxiliary device of the fuel cell stack 10, and an activation burner 30 that heats the fuel cell stack 10. I have. The preheater 20 has a function of heating the gas supplied to the fuel cell stack 10 with the heat of the exhaust gas (for example, a gas obtained by further burning the remaining fuel gas after power generation), and the preheater 20 is released from the fuel cell stack 10. It has at least one of the functions of absorbing heat. The fuel cell stack 10, the preheater 20, and the starter burner 30 are accommodated in the heat insulating container 2 (see FIG. 6).

  As shown in FIGS. 2 and 3, the preheater 20 is disposed close to the side surface 14 of the fuel cell stack 10. The preheater 20 is made of a material excellent in heat resistance (for example, stainless steel) and has a substantially rectangular parallelepiped shape with a length of 10 mm × width of 180 mm × height of 225 mm. In addition, the preheater 20 generates fuel gas (hydrocarbon gas in the present embodiment) and air (oxidation gas) before being supplied to the fuel cell stack 10 by heat generated from the fuel cell stack 10 during a power generation reaction in the fuel cell stack 10. It has a function to increase the temperature of the agent gas) (function to perform preheating). The preheater 20 supplies the heated fuel gas and air to the fuel cell stack 10. In the preheater 20 of the present embodiment, a heat exchange layer (not shown) made of many metal fins is disposed in a space sandwiched between upper and lower metal plates, and the outer periphery of the heat exchange layer is a metal plate. It is a device surrounded by.

  As shown in FIG. 1, the start-up burner 30 has a substantially flat plate shape and supports the fuel cell stack 10 and the preheater 20 from below. The activation burner 30 heats the fuel cell stack 10 to an operating temperature (for example, 700 ° C.). The activation burner 30 includes a frame 31, a combustion plate 32, and a pipe 33. The combustion plate 32 is installed on the upper surface (surface) of the frame 31. The combustion plate 32 is formed of, for example, a porous ceramic material, and a mixed gas of combustible gas and air is burned on the surface. The pipe 33 protrudes from the side surface of the frame 31 and supplies the mixed gas to the combustion plate 32.

  As shown in FIGS. 1 to 3, the fuel cell stack 10 is formed by laminating a plurality of substantially rectangular plate-shaped power generation cells 11 that are the minimum unit of power generation. The fuel cell stack 10 has a substantially rectangular parallelepiped shape with a length of 180 mm × width of 180 mm × height of 80 mm. The fuel cell stack 10 has eight through holes 40 that penetrate the fuel cell stack 10 in the thickness direction. The fastening bolts 41 are inserted into the four through holes 40 at the four corners of the fuel cell stack 10, and a nut (not shown) is screwed to the lower end portion of the fastening bolt 41 protruding from the lower surface of the fuel cell stack 10. Further, gas circulation fastening bolts 42 are inserted into the remaining four through holes 40, and nuts 43 are screwed onto both end portions of the gas circulation fastening bolts 42 protruding from the upper and lower surfaces of the fuel cell stack 10. As a result, the plurality of power generation cells 11 are fixed.

  As shown in FIGS. 3 to 5, the power generation cell 11 includes a connector plate 51, an air electrode frame 52, an upper insulating frame 53 (insulating member), a separator 54, an air electrode layer 55, an electrolyte layer 56, and a fuel electrode layer 57. The lower insulating frame 58 (insulating member), the fuel electrode frame 59 and the connector plate 60 are laminated in order.

  The connector plates 51 and 60 are formed in a substantially rectangular plate shape by a metal material such as stainless steel having excellent heat resistance and conductivity, and are disposed at the upper end portion and the lower end portion of the power generation cell 11. The connector plates 51 and 60 form a gas flow path in the power generation cell 11 and make the adjacent power generation cells 11 conductive. More specifically, the connector plates 51 and 60 positioned between the adjacent power generation cells 11 serve as so-called interconnectors and partition the adjacent power generation cells 11. Note that the connector plate 60 of the present embodiment also serves as the connector plate 51 of the power generation cell 11 adjacent to the lower side. The connector plate 51 disposed at the upper end of the fuel cell stack 10 serves as the upper end plate 12, and the connector plate 60 disposed at the lower end of the fuel cell stack 10 serves as the lower end plate 13. Both end plates 12 and 13 sandwich the fuel cell stack 10 and serve as output terminals for current output from the fuel cell stack 10. In addition, the connector plates 51 and 60 used as the end plates 12 and 13 are thicker than the connector plates 51 and 60 used as the interconnector.

  As shown in FIGS. 3 to 5, the air electrode frame 52 and the fuel electrode frame 59 are formed in a substantially rectangular frame shape by a conductive material such as stainless steel. Therefore, a rectangular opening 61 that penetrates the air electrode frame 52 in the thickness direction is provided at the center of the air electrode frame 52, and the fuel electrode frame 59 is provided at the center of the fuel electrode frame 59. A rectangular opening 62 penetrating in the thickness direction is provided. The insulating frames 53 and 58 are formed in a substantially rectangular frame shape by a mica sheet having a thickness of 0.5 mm. Therefore, a rectangular opening 63 penetrating the upper insulating frame 53 in the thickness direction is provided in the central portion of the upper insulating frame 53, and the lower insulating frame 58 is provided in the central portion of the lower insulating frame 58. A rectangular opening 64 penetrating 58 in the thickness direction is provided. Furthermore, the separator 54 is formed in a substantially rectangular frame shape by a conductive material such as stainless steel. Therefore, a rectangular opening 65 penetrating the separator 54 in the thickness direction is provided at the center of the separator 54.

  As shown in FIGS. 3 to 5, the electrolyte layer 56 is formed in a rectangular plate shape by a ceramic material (oxide) such as ZrO 2. The electrolyte layer 56 is fixed to the lower surface of the separator 54 and is disposed so as to close the opening 65 of the separator 54. The electrolyte layer 56 functions as an oxygen ion conductive solid electrolyte body. An air electrode layer 55 that is in contact with the air supplied to the fuel cell stack 10 is affixed to the upper surface of the electrolyte layer 56, and a fuel gas that is also supplied to the fuel cell stack 10 is in contact with the lower surface of the electrolyte layer 56. A fuel electrode layer 57 is attached. That is, the air electrode layer 55 and the fuel electrode layer 57 are disposed on both sides of the electrolyte layer 56. The air electrode layer 55 is disposed in the opening 65 of the separator 54 so as not to contact the separator 54. The air electrode layer 55 is formed in a rectangular plate shape from a metal composite oxide, and the fuel electrode layer 57 is also formed in a rectangular plate shape from a mixture of a metal material and a ceramic material (cermet in this embodiment). ing.

  As shown in FIG. 3, in the power generation cell 11 of the present embodiment, the fuel chamber is formed below the separator 54 by the opening 64 of the lower insulating frame 58, the opening 62 of the fuel electrode frame 59, the connector plate 60, and the like. 15 is formed. Note that an electrolyte layer 56, a fuel electrode layer 57, and a fuel electrode current collector 67 are accommodated in the fuel chamber 15.

  Further, in the power generation cell 11 of the present embodiment, the air chamber 16 is formed above the separator 54 by the connector plate 51, the opening 61 of the air electrode frame 52, the opening 63 of the upper insulating frame 53, and the like. It has become. The air electrode layer 55 and the connector plate 51 are electrically connected by an air electrode current collector 66. Therefore, the insulating frames 53 and 58 are disposed and stacked in each power generation cell 11 and also serve as a seal member for the fuel chamber 15 and the air chamber 16.

  The fuel cell stack 10 includes a fuel supply path 70 that supplies fuel gas to the fuel chamber 15 of each power generation cell 11 and a fuel discharge path 80 that discharges the fuel gas from the fuel chamber 15. The fuel supply path 70 includes a fuel supply hole 71 extending along the axial direction at the center of the gas circulation fastening bolt 42, and a fuel supply lateral hole 72 that allows the fuel supply hole 71 and the fuel chamber 15 to communicate with each other. Yes. The fuel discharge path 80 includes a fuel discharge hole 81 extending in the axial direction at the center of the gas circulation fastening bolt 42 and a fuel discharge horizontal hole 82 that allows the fuel discharge hole 81 and the fuel chamber 15 to communicate with each other. Has been.

  Therefore, as shown in FIG. 3, the fuel gas sequentially passes through the fuel supply hole 71 and the fuel supply lateral hole 72 and is supplied to the fuel chamber 15, and sequentially passes through the fuel discharge lateral hole 82 and the fuel discharge hole 81. It passes through and is discharged from the fuel chamber 15. A gas pipe 451 communicating with the outside of the heat insulating container 2 via a joint 441 is connected to the top of the gas distribution fastening bolt 42 having the fuel supply hole 71 and the fuel discharge hole 81.

  The fuel cell stack 10 further includes an air supply path (not shown) for supplying air to the air chamber 16 of each power generation cell 11 and an air discharge path (not shown) for discharging air from the air chamber 16. . The air supply path has substantially the same structure as the fuel supply path 70, and includes an air supply hole (not shown) extending along the axial direction at the center of the gas circulation fastening bolt 42, an air supply hole, and an air An air supply lateral hole (not shown) that communicates with the chamber 16 is formed. The air discharge path has substantially the same structure as the fuel discharge path 80, and includes an air discharge hole (not shown) extending in the axial direction at the center of the gas circulation fastening bolt 42, and an air discharge hole. And an air discharge lateral hole (not shown) that communicates with the air chamber 16.

  Therefore, the air passes through the air supply hole and the air supply lateral hole in order and is supplied to the air chamber 16, and passes through the air discharge lateral hole and the air discharge hole in order and is discharged from the air chamber 16. A gas pipe 452 communicating with the outside of the heat insulating container 2 through a joint 442 is connected to the top of the gas circulation fastening bolt 42 having an air supply hole and an air discharge hole.

  As shown in FIGS. 1 to 5, the fuel cell 1 includes an overhang portion 91 formed by projecting a part of the upper insulating frame 53 from the side surface 14 of the fuel cell stack 10 toward the preheater 20. The overhang portion 91 is provided in the uppermost and lowermost power generation cells 11 among the plurality of power generation cells 11 constituting the fuel cell stack 10. The overhang portion 91 has a substantially rectangular plate shape with a length (amount of overhang) of 3 mm, a width of 180 mm, and a thickness of 0.5 mm. Note that the length of the overhang portion 91 is equal to the distance between the fuel cell stack 10 and the preheater 20. For this reason, the tip of the overhang portion 91 comes into contact with the preheater 20. Further, the width of the overhang portion 91 is equal to the width (horizontal length) of the fuel cell stack 10 and the width (horizontal length) of the preheater 20. For this reason, the whole front end surface of the overhang | projection part 91 contact | abuts to the preheater 20. FIG. Furthermore, the thickness of the overhang portion 91 is equal to the thickness of the insulating frames 53 and 58. In the drawings of this embodiment, the overhanging portion 91 is shown larger than the actual size for convenience of explanation.

  For example, fuel gas is introduced into the fuel chamber 15 from the fuel supply path 70 while air is introduced into the air chamber 16 from the air supply path while the inside of the heat insulating container 2 is heated to the operating temperature. As a result, hydrogen in the fuel gas and oxygen in the air react through the electrolyte layer 56 (power generation reaction), and DC power is generated with the air electrode layer 55 as the positive electrode and the fuel electrode layer 57 as the negative electrode. In the fuel cell stack 10 of the present embodiment, since a plurality of power generation cells 11 are stacked and connected in series, the upper end plate 12 electrically connected to the air electrode layer 55 becomes a positive electrode, and the fuel electrode layer The lower end plate 13 that is electrically connected to 57 serves as a negative electrode.

  Next, the system configuration of the fuel cell 1 will be described.

  As shown in FIG. 6, a fuel gas supply channel 101 that supplies fuel gas to the fuel cell stack 10 is connected to the fuel cell stack 10 that constitutes the fuel cell 1. The fuel gas supply channel 101 communicates with the fuel supply path 70 of the fuel cell stack 10 via a gas pipe 451 and a joint 441 (see FIG. 3). An electromagnetic valve 102, a desulfurizer 103, and a fuel pump 104 are installed on the fuel gas supply channel 101. The solenoid valve 102 is configured to switch the fuel gas supply channel 101 to an open state or a closed state. When the electromagnetic valve 102 is switched to the open state, the raw material gas serving as the fuel gas can be supplied to the downstream side. The electromagnetic valve 102 of the present embodiment is an electromagnetic valve that is operated by a solenoid (not shown). The desulfurizer 103 desulfurizes the raw material gas supplied from the upstream side, and supplies the desulfurized raw material gas to the downstream side. The fuel pump 104 is disposed on the downstream side of the desulfurizer 103 and supplies the raw material gas desulfurized by the desulfurizer 103 to the fuel cell stack 10 side.

  As shown in FIG. 6, an air supply channel 111 that supplies air to the fuel cell stack 10 is connected to the fuel cell stack 10. The air supply flow path 111 communicates with the air supply path of the fuel cell stack 10 via the gas pipe 452 and the joint 442. An air pump 112 is installed on the air supply channel 111. The air pump 112 supplies air taken from the outside to the preheater 20 on the fuel cell stack 10 side.

  On the other hand, the raw material gas is reformed into fuel gas (hydrogen gas) by a reformer (not shown) and then supplied to the fuel cell stack 10. At the same time, the preheater 20 heats the air supplied from the air pump 112 by the heat from the fuel cell stack 10 and supplies the heated air to the fuel cell stack 10. Gas that does not contribute to power generation and used gas after power generation are discharged from the fuel cell stack 10 via the discharge flow path 113.

  As shown in FIG. 6, a gas supply passage 121 that supplies air and ignition gas to the activation burner 30 is connected to the activation burner 30 that constitutes the fuel cell 1. The gas supply channel 121 is branched into an air supply pipe 122 and a gas supply pipe 123 on the upstream side. An air blower 124 is installed on the air supply pipe 122. The air blower 124 supplies air taken from the outside to the activation burner 30. On the other hand, an electromagnetic valve 125 is installed on the gas supply pipe 123. The electromagnetic valve 125 switches the gas supply pipe 123 to an open state or a closed state. When the solenoid valve 125 is switched to the open state, the ignition gas can be supplied to the downstream side. Note that the electromagnetic valve 125 of the present embodiment is an electromagnetic valve that is operated by a solenoid (not shown).

  A proportional valve 126 is installed at a connection portion between the air supply pipe 122 and the gas supply pipe 123. The proportional valve 126 adjusts the ratio (air-fuel ratio) between the amount of air supplied from the air supply pipe 122 to the activation burner 30 and the amount of ignition gas supplied from the gas supply pipe 123 to the activation burner 30. It is supposed to be. The air and ignition gas sent to the starter burner 30 are ignited by an ignition source (not shown) to heat the inside of the heat insulating container 2.

  As shown in FIG. 6, the fuel cell 1 includes a control device 131 that controls the entire system. The control device 131 includes a CPU, a ROM, a RAM, an input / output circuit, and the like. The CPU is electrically connected to the electromagnetic valves 102 and 125, the fuel pump 104, the air pump 112, the air blower 124, and the proportional valve 126, and controls them by various drive signals.

  Next, a method for manufacturing the fuel cell 1 will be described.

  First, the connector plates 51, 60, the air electrode frame 52, the separator 54, and the fuel electrode frame 59 are formed by punching a stainless steel plate. Further, the insulating frames 53 and 58 are manufactured by forming the mica sheet into a predetermined shape. Specifically, a commercially available mica sheet (a sheet made of a composite of mica and molding resin) is almost the same as other members (connector plates 51, 60, air electrode frame 52, separator 54, fuel electrode frame 59, etc.). It forms in the same shape (however, except the overhang | projection part 91). Note that the mica sheet is formed to be larger than the other members only in the portion that becomes the overhanging portion 91. Moreover, the resin component contained in the mica sheet evaporates by heat treatment performed after being laminated together with other members. Further, the mica sheet seals each member by being sandwiched between other members when each power generation cell 11 is bolted in the stacking direction.

  Next, the power generation cell 11 is formed according to a conventionally known technique. Specifically, a green sheet to be the electrolyte layer 56 is laminated on the green sheet to be the fuel electrode layer 57 and fired. Further, a material for forming the air electrode layer 55 is printed on the electrolyte layer 56 and then fired (at this time, a single cell of SOFC is obtained). The electrolyte layer 56 is fixed to the separator 54 by brazing. Then, the connector plates 51, 60, the air electrode frame 52, the insulating frames 53, 58, the separator 54 (the SOFC single cell is fixed by brazing), the fuel electrode frame 59, and the like are laminated and integrated. As a result, the power generation cell 11 is formed.

  Next, the fuel cell stack 10 is formed by stacking and integrating the power generation cells 11. More specifically, the fastening bolts 41 are inserted into the four through holes 40 at the four corners of the fuel cell stack 10, and a nut (not shown) is screwed to the lower end portion of the fastening bolt 41 protruding from the lower surface of the fuel cell stack 10. . Further, gas circulation fastening bolts 42 are inserted into the remaining four through holes 40, and nuts 43 are screwed onto both end portions of the gas circulation fastening bolts 42 protruding from the upper and lower surfaces of the fuel cell stack 10. As a result, each power generation cell 11 is fixed.

  Then, when the fuel cell stack 10 and the preheater 20 are mounted on the activation burner 30, the fuel cell 1 is completed. Note that the overhanging portion 91 is brought into contact with the preheater 20 between the fuel cell stack 10 and the preheater 20.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) The fuel cell 1 of the present embodiment includes an overhang portion 91 formed by projecting a part of the upper insulating frame 53 constituting the fuel cell stack 10 from the side surface 14 of the fuel cell stack 10 toward the preheater 20. ing. As a result, since the distance between the fuel cell stack 10 and the preheater 20 is kept constant via the overhanging portion 91, for example, even if the fuel cell stack 10 and the preheater 20 are deformed by repeated thermal cycles, both Is avoided. Therefore, a short circuit occurring between the fuel cell stack 10 and the preheater 20 is prevented, and the reliability of the fuel cell 1 can be increased. In addition, since a part of the upper insulating frame 53 becomes the overhang portion 91, the overhang portion 91 is integrated with the fuel cell stack 10. Therefore, there is no need to provide a fixing means for fixing the overhang portion 91 to the fuel cell stack 10. Therefore, the number of parts of the fuel cell 1 is reduced, and the number of man-hours at the time of manufacture is also reduced, so that the cost of the fuel cell 1 can be reduced. Further, since the overhang portion 91 is integrated with the fuel cell stack 10, the strength of the overhang portion 91 is improved. Moreover, since the displacement of the upper insulating frame 53 having the overhang portion 91 is prevented by vibration, the displacement of the preheater 20 with which the overhang portion 91 abuts is prevented.

  (2) In this embodiment, since the overhang | projection part 91 is each arrange | positioned at the power generation cell 11 of the uppermost layer and the lowest layer, both the overhang | projection parts 91 are mutually spaced apart. As a result, the leading ends of the two overhang portions 91 come into contact with the upper end portion and the lower end portion of the preheater 20, so that it is easy to stably maintain the distance between the fuel cell stack 10 and the preheater 20.

  (3) In the present embodiment, the vertical and horizontal lengths of the upper insulating frame 53 excluding the protruding portion 91 are 180 mm, which is the same as the vertical and horizontal lengths of the fuel cell stack 10, whereas The overhang amount (3 mm) of the portion 91 is considerably small. Therefore, even if the overhanging portion 91 is formed in the upper insulating frame 53, the overhanging portion 91 is securely held without being bent by the upper insulating frame 53 being sandwiched between the air electrode frame 52 and the separator 54. Is done. Even if the overhanging portion 91 is formed in the lower insulating frame 58, the overhanging portion 91 may be bent due to the lower insulating frame 58 being sandwiched between the separator 54 and the fuel electrode frame 59. It is securely held without Therefore, the tip of the overhanging portion 91 can be reliably brought into contact with the preheater 20, so that the reliability of the fuel cell 1 is improved.

  In addition, you may change this embodiment as follows.

-The overhang | projection part 91 which makes a substantially rectangular plate shape was provided in the upper side insulation frame 53 of the said embodiment. However, as shown in FIG. 7, the upper insulating frame 96 having a substantially rectangular ring shape is formed in the projecting portion 95 with the opening portion 94 communicating with both side surfaces (the upper surface 92 and the lower surface) in the stacking direction of the power generation cells 11. It may be. The opening 94 has a rectangular shape in plan view of 2 mm long × 170 mm wide. For this reason, the opening area of the opening 94 is 340 mm ² . In this embodiment, the area of the upper surface 92 (and the lower surface) of the overhang portion 95 is 540 mm ² (= 3 × 180 mm ² ), and the ratio of the opening 94 in the overhang portion 95 is about 62%. In addition to the upper insulating frame 53, the lower insulating frame 58 may be provided with a protruding portion, and an opening may be formed in the protruding portion provided in the lower insulating frame 58.

  With the above configuration, since the opening 94 is formed in the overhanging portion 95, the high-temperature burner exhaust gas and the high-temperature ambient air discharged from the startup burner 30 when the fuel cell 1 is started or after the startup. Passes through the opening 94. That is, since the high-temperature burner exhaust gas and the ambient air pass in the vicinity of the fuel cell stack 10, the fuel cell stack 10 is quickly heated by the high-temperature burner exhaust gas and the ambient air that have passed through the opening 94 to reach the operating temperature. Become. For this reason, the starting time of the fuel cell 1 can be shortened. Moreover, in the case of the opening 94 shown in FIG. 7, even if the opening 94 is formed, the entire tip of the overhanging portion 95 comes into contact with the preheater 20, so that the fuel cell stack 10 and the preheater 20 It becomes easy to keep the interval of stable.

  In the above embodiment, the width of the overhang portion 91 is equal to the width of the upper insulating frame 53 (the width of the fuel cell stack 10), but as shown in FIGS. The width of 212 may be smaller than the width of the insulating frames 213 and 214. In this case, in the insulating frame 213 shown in FIG. 8, cutout portions 215 (openings) having a substantially L shape when viewed from the thickness direction are arranged at both ends of the overhang portion 211. Become. The notch portion 215 communicates the upper surface 217 and the lower surface of the overhang portion 211 and opens at the tip and side edges of the overhang portion 211. Further, in the insulating frame 214 shown in FIG. 9, a notch 216 (opening) having a substantially U-shape when viewed from the thickness direction is arranged at the center of the protruding portion 212. The notch 216 communicates with the upper surface 218 and the lower surface of the overhang portion 212 and opens at the tip of the overhang portion 212.

  In this way, since the notches 215 and 216 are formed in the overhang portions 211 and 212, the high-temperature burner exhaust gas discharged from the starter burner 30 at the start and after the start of the fuel cell 1 Hot ambient air will pass through the notches 215, 216. That is, since the high-temperature burner exhaust gas and ambient air pass in the vicinity of the fuel cell stack 10, the fuel cell stack 10 is quickly warmed by the high-temperature burner exhaust gas and ambient air that have passed through the notches 215 and 216 to reach the operating temperature. It becomes like this. For this reason, the starting time of the fuel cell 1 can be shortened.

  In the fuel cell 1 of the above embodiment, the overhang portion 91 is provided in the upper insulating frame 53, but the overhang portion 91 may be provided also in the lower insulating frame 58. Further, instead of providing the overhanging portion 91 in the upper insulating frame 53, the overhanging portion 91 may be provided in the lower insulating frame 58.

  -The fuel cell 1 of the said embodiment was provided with the overhang | projection part 91 formed by protruding a part of the upper side insulation flame | frame 53 toward the preheater 20 from the side surface 14 of the fuel cell stack 10. FIG. However, as shown in FIG. 10, the fuel cell 140 includes an overhanging portion 145 that is formed by protruding a part of the connector plate 141 that is a conductive metal member from the side surface 143 of the fuel cell stack 142 toward the preheater 144. It may be. Note that the air electrode frame 52, the separator 54, the fuel electrode frame 59, and the like may be used as the conductive metal member on which the overhang portion is formed.

  In addition, when providing the overhang | projection part 145 in the connector plate 141, the connector plate 141 and the preheater 144 are electrically insulated from the front end surface of the overhang | projection part 145, and the upper surface and lower surface of the front-end | tip part of the overhang | projection part 145. An insulating coating 146 is integrally formed. Here, the insulating coating 146 is preferably a heat resistant insulating coating mainly composed of an oxide ceramic such as alumina. Further, the insulating coating 146 may be formed on the entire outer surface of the connector plate 141.

  In the fuel cell 1 of the above embodiment, the tip of the overhang portion 91 is in contact with the preheater 20. However, as shown in FIG. 11, the fuel cell 150 may be configured such that the tip of the overhanging portion 151 is fitted and fixed in a recess 153 provided in the preheater 152.

  In the above-described embodiment, the overhang portion 91 is disposed only in the power generation cells 11 in the uppermost layer and the lowermost layer, but the arrangement mode of the overhang portion 91 may be changed. For example, the overhang portion 91 may be arranged in the power generation cell 11 in the intermediate layer. Further, the overhang portion 91 may be disposed in all the power generation cells 11 or only in one power generation cell 11. If the number of the overhang portions 91 is increased, contact between the fuel cell stack 10 and the preheater 20 can be avoided more reliably, and the reliability of the fuel cell 1 is further increased.

  In the above embodiment, the thickness of the insulating frames 53 and 58 (mica sheet) is 0.5 mm, and the thickness of the overhanging portion 91 is equal to the thickness of the insulating frames 53 and 58. That is, the thickness of the overhang portion 91 formed in the uppermost power generation cell 11 is equal to the thickness of the overhang portion 91 formed in the lowermost power generation cell 11. However, you may change the thickness of the overhang | projection part 91 suitably. For example, the overhang 91 formed in the uppermost power generation cell 11 may be thicker or thinner than the overhang 91 formed in the lowermost power generation cell 11.

  In the above embodiment, the insulating frames 53 and 58 are formed of a mica sheet having a thickness of 0.5 mm. However, the thickness of the mica sheet forming the insulating frames 53 and 58 may be changed to, for example, 0.3 mm and 2 mm. Further, thicker insulating frames 53 and 58 may be formed by overlapping mica sheets.

  As in the fuel cell stack 160 shown in FIG. 12, the opening 162 provided in the overhanging portion 161 and the opening 164 provided in the overhanging portion 163 extend along the side surface 165 of the fuel cell stack 160. You may shift and arrange | position to a direction (direction orthogonal to the direction where the electric power generation cell 11 laminates | stacks). In this way, when the high-temperature burner exhaust gas or the high-temperature ambient air discharged from the activation burner 30 rises and passes through the openings 162 and 164, the burner exhaust gas and the ambient air are overhang portions 161 and 163. Therefore, the fuel cell stack 160 can be warmed more quickly.

  In the fuel cell stack 10 of the above embodiment, only one preheater 20 is disposed on one side surface 14. However, as shown in FIG. 13, a fuel cell stack 170 in which a plurality of (two in FIG. 13) preheaters 172 are arranged on one side 171 may be used. Further, as shown in FIG. 17, a fuel cell stack 190 in which one preheater 193 is arranged on each of the side surfaces 191 and 192 adjacent to each other may be used. Further, as shown in FIGS. 14 and 15, a fuel cell stack 180 in which one preheater 183 and 184 is arranged on each of side surfaces 181 and 182 located on opposite sides may be used. In this case, the preheater 183 comes into contact with the tip of an overhang portion 186 that is formed by protruding a part of the insulating frame 185 from the side surface 181 of the fuel cell stack 180, and the preheater 184 is separated from the insulating frame 185. The tip of an overhanging portion 188 that protrudes from a side surface 182 of the fuel cell stack 180 contacts a part of the insulating frame 187. As shown in FIG. 16, an overhang portion 202 that projects from the side surface 181 and an overhang portion 203 that projects from the side surface 182 are formed on one insulating frame 201. The front end may be brought into contact with the preheater 183 and the front end of the overhang portion 203 may be brought into contact with the preheater 184.

  In the above embodiment, the insulating frames 53 and 58 are used as insulating members, but other members may be used as insulating members. For example, instead of using the insulating frames 53 and 58, an insulating piece (not shown) having a rectangular shape in plan view attached on the separator 54 or the fuel electrode frame 59 may be used as the insulating member. In this case, the protruding portion protrudes from the outer peripheral edge of the insulating piece and protrudes from the side surface 14 of the fuel cell stack 10 toward the preheater 20.

  In the fuel cell 1 of the above embodiment, the preheater 20 is used as an auxiliary device that assists the fuel cell stack 10. However, a heater, a vaporizer, a reformer, or the like may be used as an auxiliary device. More specifically, the heat generator includes a combustion catalyst, and has a function of preventing the remaining fuel gas from being discharged from the fuel cell 1 by burning the remaining fuel gas discharged from the fuel cell stack 10 after power generation. Yes. Further, the vaporizer vaporizes water, which is a liquid raw material, by heat from the start burner 30 or heat from combustion of the remaining fuel gas when the fuel cell 1 is started, for example, and the vaporized water (water vapor) is converted into a fuel cell stack. 10 is provided. Further, the reformer includes a reforming catalyst (for example, ruthenium or nickel), reforms the raw material (hydrocarbon in this embodiment) using steam, and supplies the reformed raw material to the fuel cell stack 10. By supplying, the fuel electrode layer 57 has a function of preventing carbon deposition and temperature decrease.

  Next, the technical ideas grasped by the embodiment described above are listed below.

  (1) In the fuel cell according to the first or second aspect, the width of the overhanging portion is equal to the width of the auxiliary device, and the entire distal end surface of the overhanging portion is in contact with the auxiliary device. .

  (2) In the above means 1 or 2, the fuel cell stack has a plurality of the insulating members, and the thickness of the insulating members is equal to each other.

DESCRIPTION OF SYMBOLS 1,140,150 ... Fuel cell 10,142,160,170,180,190 ... Fuel cell stack 14,143,165,171,181,182,191,192 ... Fuel cell stack side surface 11 ... Power generation cell 20, 144, 152, 172, 183, 184, 193 ... Preheaters 53, 96 as auxiliary devices ... Upper insulating frame 55 as insulating member ... Air electrode layer 56 ... Electrolyte layer 57 ... Fuel electrode layer 58 ... Under insulating member Side insulating frames 91, 95, 145, 151, 161, 163, 186, 188, 202, 203, 211, 212 ... overhangs 92, 217, 218 ... upper surfaces 94, 162, 164 as side surfaces of the overhangs 215, 216 ... opening 141 ... connector plate 146 as a conductive metal member ... insulating coating 153 ... recesses 185, 187, 2 1,213,214 ... insulation frame as an insulating member

Claims (7)

A fuel cell stack in which a plurality of power generation cells having an electrolyte layer, a fuel electrode layer disposed on both sides thereof and in contact with a fuel gas, and an air electrode layer in contact with an oxidant gas are stacked to generate power by a power generation reaction;
In the power generation reaction in the fuel cell stack, at least one of the functions of preheating the raw material including the oxidant and fuel, burning the residual fuel gas after power generation, vaporizing the liquid raw material, and reforming the raw material is performed. A fuel cell comprising an auxiliary device disposed in proximity to a side surface of the fuel cell stack,
A fuel cell comprising: an overhanging portion formed by projecting a part of an insulating member constituting the fuel cell stack from a side surface of the fuel cell stack toward the auxiliary device. A fuel cell stack in which a plurality of power generation cells having an electrolyte layer, a fuel electrode layer disposed on both sides thereof and in contact with a fuel gas, and an air electrode layer in contact with an oxidant gas are stacked to generate power by a power generation reaction;
In the power generation reaction in the fuel cell stack, at least one of the functions of preheating the raw material including the oxidant and fuel, burning the residual fuel gas after power generation, vaporizing the liquid raw material, and reforming the raw material is performed. A fuel cell comprising an auxiliary device disposed in proximity to a side surface of the fuel cell stack,
The fuel cell stack includes a projecting portion formed by projecting a part of the conductive metal member from the side surface of the fuel cell stack toward the auxiliary device, and an insulating coating is integrally formed on the projecting portion. A fuel cell characterized by comprising:   2. The fuel cell according to claim 1, wherein the insulating member constituting the fuel cell stack is an insulating frame that is disposed and stacked in the plurality of power generation cells and also serves as a seal member.   The fuel cell according to claim 2, wherein the insulating coating is a heat-resistant insulating coating mainly composed of an oxide ceramic.   The fuel cell according to any one of claims 1 to 4, wherein a tip of the overhanging portion is in contact with the auxiliary device.   6. The fuel cell according to claim 5, wherein a tip of the overhanging portion is fitted and fixed in a recess provided in the auxiliary device.   The fuel cell according to any one of claims 1 to 6, wherein an opening for communicating both side surfaces in the stacking direction is formed in the overhanging portion.

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