JP5395488B2 - Fuel cell device - Google Patents

Description

  The present invention relates to a fuel cell device that heats a reforming section with a combustion flame.

  A fuel cell device of this type includes a reforming unit that reforms a fuel raw material to generate an anode gas, a fuel cell that generates power using the anode gas and the cathode gas generated in the reforming unit, and a fuel cell. There is known a technique in which a reforming section is heated by a combustion flame obtained by burning anode off-gas discharged from a combustion space (Patent Documents 1 and 2).

JP 2005-158527 A JP 2008-66127 A

  According to the fuel cell device described above, the reforming section can be efficiently heated by the combustion flame obtained by burning the anode off-gas discharged from the fuel cell in the combustion space. Furthermore, in the industry, it is required to improve the heating efficiency of the reforming section.

  The present invention has been made in view of the above-described circumstances, and increases the probability that the high-temperature combustion exhaust gas of the combustion flame contacts the reforming section, and between the high-temperature combustion exhaust gas of the combustion flame and the reforming section. It is an object of the present invention to provide a fuel cell device with improved heat exchange efficiency and improved heating efficiency for the reforming section.

A fuel cell device according to the present invention includes (i) a reforming unit that reforms a fuel raw material to generate an anode gas, and (ii) an anode gas and a cathode gas that are generated in the reforming unit, and generates power. A fuel cell that heats the reforming unit with a combustion flame in which the anode off-gas discharged from the battery is combusted in a combustion space; and (iii) an anode gas that supplies the anode gas generated in the reforming unit to the inside of the fuel cell. A passage, (iv) a cathode gas passage for supplying cathode gas to the cathode of the fuel cell, (v) a contact passage for bringing the combustion exhaust gas in the combustion space into contact with the reforming section, and a downstream of the contact passage and exhaust. An exhaust gas passage having a downstream passage toward the gas outlet; (vi) covering the combustion space in which the combustion flame burns, and facilitating the flow of the combustion exhaust gas in the combustion space to the contact passage; and The combustion exhaust gas in the combustion space is via a contact path; and a cover member for directing downstream passageway, (vii) the combustion space for the first combustion so as to sandwich the channel forming member for forming a cathode gas passage (Viii) a passage forming member that forms the cathode gas passage has a communication passage that connects the first combustion space and the second combustion space; and (ix) each of the first combustion space and the second combustion space, that are arranged to sandwich between the passage forming member and the cover member.

  The anode gas generated in the reforming unit is supplied into the fuel cell. The cathode gas is supplied into the fuel cell. As a result, the fuel cell generates electricity. The anode off-gas after the power generation reaction discharged from the fuel cell is burned in the combustion space and becomes a combustion flame. The combustion flame heats the reforming section. As a result, the reforming section is heated to a temperature suitable for the reforming reaction.

  The cover member covers the combustion space where the combustion flame burns. Thus, the cover member promotes the flow of combustion exhaust gas (hereinafter also referred to as exhaust gas) in the combustion space into the contact passage. Therefore, the cover member positively directs the exhaust gas in the combustion space toward the downstream passage via the contact passage. For this reason, it is suppressed that the exhaust gas of the space for combustion flows into parts other than a contact passage, and it goes through a contact passage. For this reason, the flow rate of the exhaust gas per unit time flowing through the contact passage increases. Therefore, the probability that the high-temperature exhaust gas flowing through the contact passage comes into contact with the reforming portion increases. The heat exchange efficiency between the high temperature exhaust gas and the reforming section is improved, and the heating efficiency of the reforming section is increased.

  According to the fuel cell device of the present invention, the cover member promotes the flow of the exhaust gas in the combustion space to the contact passage, and directs the exhaust gas in the combustion space to the downstream passage through the contact passage. Dodge. For this reason, it is suppressed that the exhaust gas of the space for combustion flows into parts other than a contact passage, and going to a contact passage is promoted. For this reason, the flow rate of the exhaust gas flowing through the contact passage increases. Therefore, the heat exchange efficiency between the exhaust gas flowing through the contact passage and the reforming section is improved, and the heating efficiency of the reforming section is increased. For this reason, the reforming reaction in the reforming section is improved, and the power generation efficiency of the fuel cell is ensured.

1 is a cross-sectional view of a fuel cell device according to Embodiment 1. FIG. FIG. 3 is a perspective view partially showing an opposing passage of a cathode gas passage of the fuel cell device according to the first embodiment. 1 is a cross-sectional view of a main part of a fuel cell device according to Embodiment 1. FIG. FIG. 3 is a conceptual diagram illustrating the vicinity of a fuel cell and a reforming unit according to the first embodiment. 1 is a perspective view showing a concept in the vicinity of a fuel cell and a reforming unit according to Embodiment 1. FIG. FIG. 6 is a cross-sectional view of a main part of a fuel cell device according to Embodiment 2. FIG. 10 is a cross-sectional view of the main part of the fuel cell device according to Embodiment 3. FIG. 10 is a cross-sectional view schematically showing a state where the cover member is in contact with the side surface of the reforming unit according to the third embodiment. 10 is a cross-sectional view of a fuel cell device according to Embodiment 4. FIG. 10 is a cross-sectional view of a fuel cell device according to Embodiment 5. FIG. FIG. 10 is a cross-sectional view of a fuel cell device according to Embodiment 6. FIG. 10 is a perspective view of a main part of a fuel cell device according to Embodiment 6.

  The cover member covers the combustion space where the combustion flame burns and directs the exhaust gas in the combustion space toward the contact passage. The cover member can be in contact with the reforming portion so as to cover the combustion space. In this case, the cover member may be fixed to the reforming portion or may be press-contacted. When the cover member is fixed to the reforming portion, the supportability of the reforming portion can be improved.

  According to a preferred embodiment, in the cross section, the combustion space has a first combustion space and a second combustion space so as to sandwich a passage forming member that forms a cathode gas passage. In this case, it is preferable that the passage forming member that forms the cathode gas passage has a communication passage that connects the first combustion space and the second combustion space. In this case, the communication between the first combustion space and the second combustion space is ensured by the communication path. Therefore, good gas flowability is ensured between the first combustion space and the second combustion space. For this reason, it is possible to contribute to reducing variations in the combustibility of the combustion flame in the first combustion space and the combustibility of the combustion flame in the second combustion space.

  According to a preferred embodiment, the cathode gas passage has an opposing passage that faces the fuel cell and receives heat from the fuel cell. In this case, a first passage is provided between the fuel cell and the opposing passage to allow the cathode gas supplied from the opposing passage of the cathode gas passage and not flowing into the fuel cell to flow toward the combustion space. Preferably it is. In this case, it is preferable that the direction in which the cathode gas flows in the first passage and the direction in which the cathode gas flows in the opposite passage of the cathode gas passage are opposite to each other. This is advantageous in improving the efficiency of heat exchange between the cathode gas in the first passage and the cathode gas in the opposite passage of the cathode gas passage.

  According to a preferred embodiment, a second passage is provided between the fuel cell and the cover member to allow the cathode gas supplied from the cathode gas passage and not flowing into the fuel cell to flow toward the combustion space. Yes. In this case, the cover member is easily heated by heat transfer from the fuel cell. The cover member heated in this way is advantageous for heating the cathode gas flowing through the second passage toward the combustion space. Therefore, it is advantageous to increase the combustion efficiency in the combustion space.

  According to a preferred embodiment, at least the surface of the cover member that forms the second passage absorbs radiant heat from the stack and / or the combustion flame so as to increase the temperature rise performance of the cathode gas passing through the second passage. A radiant heat absorption treatment is performed to increase the absorption rate. In this case, the surface of the cover member is advantageous for heating the cathode gas flowing toward the combustion space through the second passage and increasing the combustion efficiency in the combustion space.

  According to a preferred embodiment, at least the surface of the cover member that forms the second passage is subjected to a radiant heat reflection process that increases the reflectivity for reflecting the radiant heat from the stack and / or the combustion flame. In this case, it is possible to contribute to keeping the temperature of the stack and / or the combustion flame high. The radiant heat absorption treatment described above can be performed on the surface of a member such as a passage forming member that forms a passage constituting the fuel cell device.

(Embodiment 1)
1 to 5 show the first embodiment. This embodiment shows an example applied to a solid oxide fuel cell device. FIG. 1 shows the concept of the fuel cell device according to the first embodiment. The fuel cell device 1 includes a stack 2 in which a plurality of fuel cells are stacked in the thickness direction and extend along a longitudinal direction (a direction perpendicular to the paper in FIG. 1). The fuel cell device 1 includes a base 3, a stack 2 formed of a fuel cell 20 accommodated in a placement chamber 30 of the base 3 via a seal portion 20 w that also serves as a spacer, and a stack 2 in the placement chamber 30 of the base 3. The reformer 4 disposed on the upper side, the combustion space 5 formed between the upper surface of the stack 2 and the lower surface of the reformer 4, and the heat insulation formed of the heat insulating material disposed on the outside of the stack 2 It has a layer 6, an exhaust gas passage 7 disposed outside the heat insulating layer 6, and a cathode gas passage 8 disposed outside the exhaust gas passage 7. Here, the exhaust gas passage 7 and the cathode gas passage 8 are extended along the longitudinal direction of the stack 2 (perpendicular to the plane of FIG. 1, the fuel cell stacking direction). The exhaust gas passage 7 is formed by passage-forming members 701 and 702 having plate shapes facing each other. The cathode gas passage 8 is formed by passage-forming members 801 and 701 having plate shapes facing each other.

4 and 5 are conceptual diagrams of the vicinity of the fuel cell 20 and the reformer 4. As shown in FIG. 5, the fuel cell 20 constituting the stack 2 is supplied with a porous conductive portion 21w having a passage 21r to which an anode gas is supplied, an anode 21 adjacent to the porous conductive portion 21w, and a cathode gas. A cathode 22 functioning as an oxidant electrode (air electrode), a membrane-like electrolyte 23 made of a solid oxide sandwiched between the anode 21 and the cathode 22, and a connector 20x. The solid oxide forming the electrolyte 23 has a property of conducting oxygen ions (O ²⁻ ) at the operating temperature of the stack 2, and examples thereof include a zirconia system such as YSZ and a lanthanum gallate system. The anode 21 is exemplified by nickel-ceria cermet. Examples of the cathode 22 include samarium cobaltite and lanthanum manganite. However, the material is not limited to the above. As shown in FIG. 5, the plurality of fuel cells 20 are juxtaposed in the longitudinal direction (arrow L direction) via a gap 20 r to form a stack 2. The gap 20r faces the cathode 22. The fuel cells 20 are electrically connected to each other by a not-shown current collecting member.

  The reformer 4 includes an evaporation unit 40 that converts the reformed water into steam, and a reformer 42 that reforms the fuel material using the steam. The evaporation unit 40 has a box shape and includes a lower surface 40d, an upper surface 40u, a side surface 40s, and a side surface 40m. The reforming part 42 has a box shape and has a lower surface 42d, an upper surface 42u, a side surface 42s, and a side surface 42m. The evaporator 40 vaporizes the liquid phase reformed water supplied from the reformed water system to the evaporator 40. The reforming unit 42 includes a ceramic material that supports a reforming catalyst that promotes the reforming reaction. The reforming unit 42 is provided downstream of the evaporation unit 40 and steam-reforms the hydrocarbon-based fuel material with the steam generated by the evaporation unit 40 in a high temperature region to generate anode gas. The anode gas is hydrogen gas or hydrogen-containing gas. According to the solid oxide fuel cell, the operating temperature of the fuel cell in the steady operation of the stack 2 is, for example, preferably in the range of 450 to 1100 ° C., more preferably in the range of 550 to 800 ° C.

  As shown in FIG. 1, the cathode gas passage 8 includes an inlet 80, a first passage 81 that extends upward in the longitudinal direction from the inlet 80, a second passage 82 that extends laterally from the upper end of the first passage 81, The opposite passage 83 is a third passage extending downward from the tip of the two passages 82, and the outlet 84 is formed on the lower end side of the opposite passage 83. As shown in FIG. 2, the opposing passage 83 is a passage that receives heat from the stack 2, and is formed by a thin box-shaped passage formation portion 701 k that forms a part of the passage formation member 701. The passage forming portion 701k has a thin box shape, and has an outlet 84 communicating with the cathode of the stack 2 at the lower end.

  As shown in FIG. 1, the exhaust gas passage 7 is formed by passage forming members 701 and 702 whose base material is metal. The exhaust gas passage 7 includes a contact passage 70 that is in direct contact with the reformer 4 and a downstream passage 73 that extends so as to communicate with the downstream of the contact passage 70. The downstream passage 73 has an inlet 72 and an outlet 74 (exhaust gas outlet). The downstream passage 73 through which the relatively high temperature side exhaust gas flows constitutes a heat exchanger 7 </ b> X that exchanges heat with the relatively low temperature side cathode gas that flows through the first passage 81 of the cathode gas passage 8.

  As shown in FIG. 1, the contact passage 70 is located between the combustion space 5 and the exhaust gas passage 7 so as to communicate with them. The contact passage 70 includes a first contact passage 70 f that contacts the side surface 42 s of the reforming unit 42, and a second contact passage 70 s that contacts the upper surface 42 u of the reforming unit 42. The first contact passage 70f faces the opposite passage 83 through a passage forming portion 701k. The first contact passage 70f contacts the side surface 40s and the passage formation portion 701k of the evaporation unit 40. The second contact passage 70 s faces the second passage 82 of the cathode gas passage 8. The second contact passage 70s contacts the upper surface 40u of the evaporator 40.

  Two sets of stacks 2 are provided so as to sandwich the opposing passage 83 of the cathode gas passage 8. That is, the stack includes a first stack 2 f and a second stack 2 s sandwiching the opposing passage 83. As shown in FIG. 1, an anode gas manifold 24 that guides the anode gas to the inlet of the fuel cell 20 is disposed at the bottom of the stack 2. Here, the stack 2, the cathode gas passage 8, the exhaust gas passage 7, the reformer 4 and the anode gas manifold 24, and the combustion space 5 are arranged in the longitudinal direction of the fuel cell device 1 (in the direction perpendicular to the paper surface of FIG. 1). , Extending in the stacking direction of the fuel cells 20).

A description will be given of when the fuel cell 20 performs a power generation operation. In this case, since the fuel raw material pump 90 (fuel raw material conveyance source) shown in FIG. 4 is driven, the hydrocarbon-based fuel raw material is supplied to the evaporation section 40 of the reformer 4 through the fuel raw material supply passage 92. Further, the reforming water pump 93 (water conveyance source) is driven, and reforming water in a water storage tank (not shown) is supplied to the evaporation unit 40 via the reforming water passage 94. Here, since the evaporating part 40 and the reforming part 42 are heated by the combustion flame 50, the evaporating part 40 steams the liquid phase reforming water. The generated water vapor is supplied to the reforming unit 42. The reforming unit 42 steam-reforms the fuel material to generate an anode gas containing hydrogen. When the fuel raw material is methane-based, it is considered that the generation of the anode gas in the steam reforming is based on the following equation (1). In the solid oxide fuel cell 20, CO can be used as fuel in addition to H ₂ .

(1) ... CH ₄ + 2H ₂ O → 4H ₂ + CO ₂
CH ₄ + H ₂ O → 3H ₂ + CO
Assuming that CnHm is a general chemical formula for hydrocarbons, the general formula for steam reforming is the following formula (1-1). When n = 1 and m = 4, an equation for steam reforming of methane is obtained.

(1-1) ... CnHm + 2nH ₂ O → nCO ₂ + [(m / 2) + 2n)] H ₂
The produced hydrogen gas containing hydrogen is supplied to the anode inlet of the fuel cell 20 via the anode gas passage 25 and the anode gas manifold 24 and used for power generation. Further, since the cathode gas pump 95 (cathode gas carrier source) is driven, the cathode gas which is air, as shown in FIG. 1, is in the direction of arrow C1, arrow C2, arrow C3, arrow C4, arrow C5, Along the direction of arrow C6, the gas flows through the first passage 81, the second passage 82 and the opposite passage 83 of the cathode gas passage 8, and is supplied from the outlet 84 at the tip of the cathode gas passage 8 to the lower inlet of the cathode of the stack 2. Furthermore, it passes through the inside of the cathode of the stack 2 upward (in the direction of arrow U1 shown in FIG. 1) and is used for the power generation reaction of the cathode. The cathode off-gas after the power generation reaction is discharged from the upper surface of the cathode of the stack 2 to the combustion space 5. In contrast, the anode gas generated in the reforming section 22 is used for the power generation reaction of the anode while passing upward from the anode gas manifold 24 through the anode of the stack 2. As a result, the fuel cell 20 generates power. In the power generation reaction, it is considered that the reaction (2) basically occurs at the anode supplied with the hydrogen-containing gas. It is considered that the reaction (3) basically occurs at the cathode supplied with air containing oxygen. Oxygen ions (O ²⁻ ) generated at the cathode conduct the electrolyte (oxygen ion conductor, ion conductor) from the cathode 22 toward the anode.

(2) ... H ₂ + O ²⁻ → H ₂ O + 2e ⁻
When CO is contained, CO + O ²⁻ → CO ₂ + 2e ⁻
(3)... 1 / 2O ₂ + 2e ⁻ → O ²⁻
The cathode off-gas after the power generation reaction described above contains unreacted oxygen and is discharged from the upper part of the cathode of the stack 2 to the combustion space 5. Similarly, the anode off-gas after the power generation reaction contains unreacted combustion components (hydrogen), and is discharged from the upper surface of the anode of the stack 2 to the combustion space 5. As a result, the anode off gas burns with the cathode off gas in the combustion space 5 to form a combustion flame 50. The reforming part 42 and the evaporation part 40 are heated by the combustion flame 50. As a result, the reforming reaction in the reforming unit 42 is maintained, and the steam generation reaction is maintained in the evaporation unit 40. Note that according to the reaction formula (2), the anode off-gas may contain moisture (H ₂ O). According to the present embodiment, the anode gas supplied to the anode of the stack 2, that is, the flow rate of the fuel raw material supplied to the reforming unit 42, the flow rate used in the power generation reaction at the anode of the fuel cell 20, A flow rate including the flow rate at which the anode off gas forms the combustion flame 50 in the combustion space 5 is set. As the flow rate of the cathode gas, the flow rate used in the power generation reaction at the cathode of the fuel cell 20, the flow rate at which the cathode off-gas forms the combustion flame 50 as combustion air in the combustion space 5, and the surplus flow rate are added. The set flow rate is set.

  As described above, the anode off-gas and cathode off-gas after burning in the combustion space 5 become high-temperature exhaust gas. The exhaust gas enters the downstream passage 73 from the inlet 72 and flows downward, and is discharged from the outlet 74 to the outside. Here, the relatively hot exhaust gas flowing downward in the downstream passage 73 of the exhaust gas passage 7 and the first passage 81 of the cathode gas passage 8 upward (in the direction opposite to the flow direction of the exhaust gas in the downstream passage 73). The flowing relatively low temperature cathode gas exchanges heat with each other as a counter flow. Therefore, the exhaust gas is cooled and the cathode gas immediately before being supplied to the stack 2 is preheated. The above-mentioned "downward" means that the gas flows downward as a whole, including the downward direction while meandering. “Upward” means that the gas flows upward as a whole, including the upward direction while meandering. The cathode gas preheated as described above is supplied to the cathode of the fuel cell 20 through the second passage 82, the opposing passage 83, and the outlet 84 of the cathode gas passage 8, thereby improving the efficiency of the power generation reaction at the cathode. obtain.

  In other words, in the heat exchanger 7X, the high temperature exhaust gas flowing through the downstream passage 73 of the exhaust gas passage 7 flows downward. The low-temperature cathode gas flowing through the first passage 81 of the cathode gas passage 8 flows upward. As a result, the high-temperature exhaust gas and the low-temperature cathode gas become counterflows that flow in opposite directions and exchange heat with each other. Accordingly, the hot exhaust gas discharged from the combustion space 5 is efficiently cooled by the cathode gas in the downstream passage 73, and the cathode gas immediately before being supplied to the stack 2 is efficiently preheated by the exhaust gas. Thus, the downstream passage 73 can function as a heat exchange passage.

  Now, according to this embodiment, as shown in FIG. 1, the plate-shaped cover member 210 which covers the combustion space 5 in which the combustion flame 50 burns is provided. The material of the cover member 210 is not particularly limited, and examples thereof include metals and refractories. The metal preferably has corrosion resistance and strength at high temperatures, and examples thereof include alloy steels such as stainless steel (ferritic, austenitic, martensitic), and carbon steel. As shown in FIGS. 1 and 2, the upper end portion 206 of the cover member 210 is hermetically in contact with the side surface 42 m of the reforming unit 42 and the side surface 40 m of the evaporation unit 40 for sealing. In this case, the upper end portion 206 of the cover member 210 may be fixed in contact with the side surface 42m of the reforming unit and the side surface 40m of the evaporation unit 40 by welding or a fixture, or simply in airtight contact. You can just be there. As shown in FIG. 1, the upper surface 207 of the upper end portion 206 of the cover member 210 protrudes above the upper surface of the stack 2, the lower surface 42 d of the reforming unit 42, and the lower surface 40 d of the evaporation unit 40. Here, the upper surface 207 is located below the upper surface 42u of the reforming unit 42 and the upper surface 40u of the evaporation unit 40, and gas flowability in the second contact passage 70s is ensured. According to the present embodiment having such a cover member 210, the high-temperature exhaust gas burned in the combustion space 5 is positively directed to the first contact passage 70 f of the contact passage 70 and the second contact passage 70 s. be able to. For this reason, it is suppressed that the hot exhaust gas discharged from the combustion space 5 flows in a short circuit to a portion other than the contact passage 70. That is, the high-temperature exhaust gas in the combustion space 5 does not flow into the first contact passage 70f, but is prevented from flowing directly from the combustion space 5 to the inlet 72 of the exhaust gas passage 7 in a short circuit.

  As a result, the flow rate of the exhaust gas flowing through the first contact passage 70f of the contact passage 70 and the second contact passage 70s increases. Therefore, the contact probability between the exhaust gas flowing through the first contact passage 70f and the side surface 42s of the reforming section 42, and hence the heat exchange efficiency, is improved. In addition, the contact probability between the high-temperature exhaust gas flowing through the second contact passage 70s and the upper surface 42u of the reforming section 42, and hence the heat exchange efficiency, are improved. Therefore, the heating efficiency with which the exhaust gas heats the reforming section 42 can be increased.

  The same applies to the evaporation unit 40. That is, the heat exchange efficiency in which the high-temperature exhaust gas flowing through the first contact passage 70f exchanges heat with the side surface 40s of the evaporation unit 40 is improved. Furthermore, the heat exchange efficiency between the high-temperature exhaust gas flowing through the second contact passage 70s and the upper surface 40u of the evaporation unit 40 is improved. Thus, the heating efficiency of the evaporation part 40 is improved. In particular, when the generated power of the stack 2 is small, the flow rate of the anode gas and cathode gas supplied to the stack 2 per unit time is small. For this reason, the ratio in which the reforming part 42 and the evaporation part 40 become channel resistance becomes high. In this case, when the cover member is not provided, the exhaust gas in the combustion space 5 easily flows from the combustion space 5 to the inlet 72 of the exhaust gas passage 7 in a short circuit. In this case, it is conceivable that the frequency with which the high-temperature exhaust gas comes into contact with the reforming unit 42 and the evaporation unit 40 decreases, and the heating efficiency of the reforming unit 42 and the evaporation unit 40 decreases. However, according to the present embodiment, since the cover member 210 for preventing the short-circuit flow of the exhaust gas is provided, the contact between the reforming unit 42 and the evaporation unit 40 and the exhaust gas is improved as described above. The heating efficiency of heating the reforming section 42 and the evaporation section 40 with exhaust gas can be increased.

  Furthermore, according to the present embodiment, as can be understood from FIG. 1, the hot exhaust gas in the combustion space 5 flows into the first contact passage 70f. For this reason, the heating efficiency which heats the cathode gas which flows through the opposing channel | path 83 with the hot exhaust gas of the 1st contact channel | path 70f can be improved. For this reason, it can contribute to heating the cathode gas of the opposing channel | path 83 just before supplied to the stack 2 efficiently. The lower end portion 205 of the cover member 210 is fixed to the fixing portion 350 by welding or a fixture, and the upper end portion 206 of the cover member 200 is welded or attached to the side surface 42 m of the reforming portion 42 of the reformer 4. It is preferably fixed. In this case, the cover member 210 can assist the support of the reforming unit 40 of the reformer 4, and the support of the reformer 4 can be improved. However, it is not limited to this.

  By the way, the power generation reaction of the stack 2 is an exothermic reaction. Inside the stack 2, as described above, the anode gas and the cathode gas flow upward. For this reason, when considering the power generation reaction in the stack 2 and further considering the existence of the combustion flame 50 above the stack 2, the upper part of the stack 2 tends to be hotter than the lower part in the height direction. The temperature of the stack 2 greatly affects the power generation reaction of the stack 2. Considering this, it is preferable to avoid an increase in the temperature difference between the upper part and the lower part of the stack 2 in order to make the power generation reaction uniform in the height direction of the stack 2.

  In this regard, according to the present embodiment, as shown in FIG. 1, of the passage forming member 701 that forms the cathode gas passage 8, the passage forming portion 701 k that forms the opposing passage 83 includes the first contact passage 70 f and the stack. 2 faces the side 2k. The passage forming portion 701k and the side surface 2k of the stack 2 form a first passage 310 in which the cathode gas flows upward (in the direction of arrow U2). That is, the first passage 310 is a passage through which the cathode gas supplied from the opposing passage 83 of the cathode gas passage 8 and not flowing into the cathode of the stack 2 flows upward (in the direction of arrow U2) toward the combustion space 53. is there. Here, the direction in which the cathode gas flows in the first passage 310 (arrow U2 direction, upward) and the direction in which the cathode gas flows in the opposing passage 83 (arrow C5 direction, downward) are opposite to each other. The cathode gas in the facing passage 83 is heated by receiving heat from the side surface 2k of the stack 2 toward the lower portion of the facing passage 83.

  For this reason, in the opposing channel | path 83, the lower part becomes a relative high temperature area | region, and it is thought that the upper part becomes a relative low temperature area | region. On the other hand, when the cathode gas flows upward (in the direction of arrow U2) through the first passage 310, the upper portion of the first passage 310 is considered to be a relatively high temperature region, and the lower portion is considered to be a relatively low temperature region. Therefore, the relatively high temperature region of the first passage 310 faces the relatively low temperature region of the opposing passage 83 via the passage forming portion 701k. Further, the relatively low temperature region of the first passage 310 faces the relatively high temperature region of the opposing passage 83 via the passage forming portion 701k. For this reason, it can contribute to making the dispersion | variation in the temperature of the upper part and the lower part in the height direction of the stack 2 small. Here, the relative high temperature region of the first passage 310 faces the relative high temperature region of the opposing passage 83 via the passage forming portion 701k, or the relative low temperature region of the first passage 310 is relative to the opposing passage 83. It is also conceivable to have a structure that faces the low temperature region via a passage forming portion 701k. In this case, there is a risk that the temperature variation in the height direction of the stack 2 increases. It is not preferable for reducing power generation variation in the height direction of the stack 2.

  As shown in FIGS. 1 and 3, the cover member 210 described above has a surface 201 that faces the side surface 2 m of the stack 2. Here, a second passage 320 through which the cathode gas flows is formed between the side surface 2 m of the stack 2 and the surface 201 of the cover member 210. Here, the cathode gas supplied from the opposite passage 83 of the cathode gas passage 8 and not flowing into the stack 2 flows into the second passage 320, and enters the combustion space 5 upward (in the direction of arrow U3) through the second passage 320. It flows toward. Thus, the side surface 2m of the stack 2 and the cover member 210 are not in direct contact. That is, since the second passage 320 that can function as a heat insulating space is formed between the side surface 2m of the stack 2 and the cover member 210, it can contribute to maintaining the stack 2 at a high temperature.

(Embodiment 2)
FIG. 6 shows a second embodiment. This embodiment has basically the same configuration and the same operation and effect as the first embodiment. In the following, different parts will be mainly described. FIG. 6 shows a cross section of the main part of the fuel cell device 1. As shown in FIG. 6, the passage forming member 701 that forms the cathode gas passage 8 has a passage forming portion 701 k that forms the opposing passage 83. The combustion space 5 has a first combustion space 5f and a second combustion space 5s so as to sandwich the opposing passage 83 and the passage forming portion 701k. As shown in FIG. 6, a plurality of cylinders 88 having communication passages 87 are fixed to the passage forming portion 701 k forming the opposing passage 83 of the cathode gas passage 8 by welding or a fixture. The communication passage 87 communicates the first combustion space 5f and the second combustion space 5s, and a plurality of communication passages 87 are intermittently formed at intervals in the direction perpendicular to the paper surface of FIG. The communication path 87 ensures good communication with the first combustion space 5f and the second combustion space 5s.

  Therefore, anode off-gas flowability and cathode gas flowability are ensured between the first combustion space 5f and the second combustion space 5s. For this reason, it is possible to contribute to the reduction in variation between the combustibility in the first combustion space 5f and the combustibility in the second combustion space 5s. Further, since a plurality of cylinders 88 are arranged at intervals in the direction perpendicular to the plane of FIG. 6, it is possible to suppress impairing the flow of the cathode gas flowing through the opposing passage 83. Furthermore, since the cathode gas flowing through the opposed passage 83 collides with the outer wall surface 88m of the cylindrical body 88, the cathode gas diffusion action can be expected, and the cathode gas temperature can be made uniform.

(Embodiment 3)
7 and 8 show the third embodiment. This embodiment has basically the same configuration and the same operation and effect as the first embodiment. In the following, different parts will be mainly described. FIG. 7 shows a cross section of the fuel cell device 1. A lower end portion 205 which is one end portion of the cover member 210 is fixed to a fixing portion 350 having heat insulation properties by welding or a fixture. The upper end portion 206 which is the other end portion of the cover member 210 has a free end shape and is in airtight contact with the side surface 42 m of the reforming portion 42. Specifically, the upper end portion 206 of the cover member 210 can also function as a leaf spring that exerts an urging force F <b> 1 (FIG. 8) toward the reforming portion 42. Due to the spring property of the upper end portion 206 of the cover member 210, the top surface 209 of the protrusion 208 formed on the upper end portion 206 is in airtight contact with the side surface 42m of the reforming portion 42 to form a seal point. The protrusion 208 is preferably continuously extended along the direction perpendicular to the plane of FIG. 7 and FIG. 8, that is, along the length direction of the modified portion 42.

  In the present embodiment, the high-temperature exhaust gas in the combustion space 5 is prevented from flowing in a short circuit to a portion other than the contact passage 70. Therefore, the hot exhaust gas goes to the first contact passage 70 f and the second contact passage 70 s of the contact passage 70. As a result, a good flow rate per unit time of the exhaust gas flowing through the first contact passage 70f and the second contact passage 70s of the contact passage 70 is ensured. Therefore, the heat exchange efficiency between the exhaust gas flowing through the contact passage 70 and the side surface 42m of the reforming unit 42 and the side surface 40m of the evaporation unit 40 is improved, and the heating efficiency of the reforming unit 42 is increased.

  According to the present embodiment, the lower end portion 205 of the cover member 210 is fixed and restrained to the fixing portion 350, but the protrusion 208 of the upper end portion 206 of the cover member 210 contacts the side surface 42m of the reforming portion 42. The reforming unit 42 and the evaporation unit 40 are not fixed. Therefore, even when the cover member 210 is thermally expanded or contracted in the length direction when the fuel cell device 1 is used or not used, the protrusion 208 is formed on the side surface 42m of the reforming unit 42 and the side surface of the evaporation unit 40. Since it slides in contact with 40 m, it is suppressed that an excessive stress concentrates on the upper end part 206 of the cover member 210. FIG. That is, the cover member 210 has a structure that absorbs thermal expansion and contraction.

(Embodiment 4)
FIG. 9 shows a fourth embodiment. This embodiment has basically the same configuration and the same operation and effect as the first embodiment. In the following, different parts will be mainly described. FIG. 9 shows a cross section of the fuel cell device 1. The heat insulation layer 6 functions as a cover member. That is, the upper end portion 6 u of the heat insulating layer 6 is applied to the side surface 42 m (the side surface of the reformer) of the reforming unit 42 and covers the combustion space 5 in which the combustion flame 50 is combusted. For this reason, the heat insulation layer 6 functioning as a cover member suppresses a short circuit directly toward the inlet 72 of the downstream passage 73 without the exhaust gas in the combustion space 5 going toward the first contact passage 70f. As a result, the exhaust gas in the combustion space 5 can be efficiently directed to the first contact passage 70 f of the contact passage 70. That is, the high-temperature exhaust gas in the combustion space 5 is suppressed from flowing to a portion of the contact passage 70 other than the first contact passage 70f. That is, all or almost all of the exhaust gas goes to the first contact passage 70 f of the contact passage 70. For this reason, the flow rate of the exhaust gas flowing through the first contact passage 70f of the contact passage 70 increases. Therefore, the heat exchange efficiency between the exhaust gas flowing through the first contact passage 70f of the contact passage 70 and the side surface 42s of the reforming section 42 is improved, and the heating efficiency of the reforming section 42 is increased. The same applies to the evaporation unit 40.

(Embodiment 5)
FIG. 10 shows a fifth embodiment. This embodiment has basically the same configuration and the same operation and effect as the first embodiment. In the following, different parts will be mainly described. As shown in FIG. 10, the cover member 210 includes a metal cover main body 209 that extends in the height direction and whose lower end 205 is fixed to the fixing portion 350 by welding or a fixture, and a tip above the cover main body 209. It has a bent portion 211 bent by press molding into an L shape toward the reforming portion 42. The bending portion 211 is fixed to the reformer 4 (the upper surface 42u of the reforming portion 42) by welding or a fixture, and does not have a through hole penetrating in the thickness direction. The cover member 210 has a projection-shaped forming portion 216 formed by press molding. Even if the cover member 210 thermally expands and contracts in the length direction, the deformation and deformation of the molding portion 216 can absorb and relax the cover member 210. As shown in FIG. 10, the bent portion 211 at the upper end of the cover member 210 is hermetically contacted and sealed with the upper surface 42 u of the reforming unit and the upper surface 40 u of the evaporation unit 40. For this reason, the exhaust gas discharged from the combustion space 5 can be prevented from flowing directly from the combustion space 5 to the inlet 72 of the exhaust gas passage 7 in a short circuit. As a result, the exhaust gas in the combustion space 5 is directed to the first contact passage 70 f of the contact passage 70.

(Embodiment 6)
11 and 12 show a sixth embodiment. This embodiment has basically the same configuration and the same operation and effect as the first embodiment. In the following, different parts will be mainly described. As shown in FIG. 11, the cover member 210 includes a cover main body 209 extending in the height direction, and a bent portion 211 bent toward the reforming portion 42 from the tip of the cover main body 209. The bent portion 211 has a plurality of through holes 213. The through hole 213 may have a slit shape extending in the arrow L direction along the bent portion 211. In this case, the contact passage 70 for positively contacting the exhaust gas and the reformer 4 is (i) a first passage formed between the opposing passage 83 of the cathode gas passage 8 and the side surface 42 s of the reforming portion 42. A contact passage 70f, (ii) a second contact passage 70s that contacts the upper surface 42u of the reforming portion 42, (iii) a surface 201 of the cover member 210, and a side surface 42m of the reforming portion 42 (a side surface 40m of the evaporation portion 40). And a bent portion 211, and a third contact passage 70t that contacts the exhaust gas and the side surface 42m. As shown in FIG. 11, the bent portion 211 of the cover member 210 is in contact with the upper surface of the reformer 4, that is, the upper surface 42 u of the reformer 42 and the upper surface 40 u of the evaporator 40. In this case, the bent portion 211 of the cover member 210 may be fixed to the upper surface 42u of the reforming unit 42 and the upper surface 40u of the evaporation unit 40, or may be only in airtight contact without being fixed.

  According to the present embodiment, as can be understood from FIG. 11, the high-temperature exhaust gas in the combustion space 5 is in contact with the side surfaces 42 s and the upper surface 42 u of the reforming section 42 and the first contact passage 70 f and the contact passage 70. The flow FA is directed to the second contact passage 70s, and the flow FB flows upward so as to penetrate the third contact passage 70t and the through hole 213 while being in contact with the side surface 42m of the reforming section 42. For this reason, also in this embodiment, it is suppressed that the hot exhaust gas discharged from the combustion space 5 flows in a short circuit to a portion other than the contact passage 70. As a result, the heat exchange efficiency between the high-temperature exhaust gas and the reforming unit 42 is improved, and the heating efficiency of the reforming unit 42 is increased. The same applies to the evaporation unit 40. The opening area of the through-hole 213 affects the ratio between the flow rate of the flow FA and the flow rate of the flow FB per unit time. If the opening area of the through hole 213 is relatively small, the flow rate of the flow FA increases, the flow rate of the exhaust gas flowing through the first contact passage 70f increases, and the flow rate of the flow FB decreases. Further, if the opening area of the through hole 213 is relatively large, the flow rate of the flow FA is reduced, the flow rate of the exhaust gas flowing through the first contact passage 70f is reduced, and the flow rate of the flow FB is increased. Thus, the advantage of being able to tune the heating efficiency of the cathode gas flowing through the opposed passage 83 and the heating efficiency of the reformer 4 is obtained by the opening area of the through hole 213.

(Embodiment 7)
Since this embodiment basically has the same configuration and the same function and effect as the above-described embodiments, FIGS. 1 to 12 can be applied mutatis mutandis. In the following, different parts will be mainly described. At least the surface 201 of the cover member 210 that forms the second passage 320 is preferably subjected to a radiant heat absorption process that increases the absorption rate for absorbing radiant heat from the stack 2 and / or the combustion flame 50. As the radiant heat absorption treatment, for example, at least the surface 201 of the cover member 210 that forms the second passage 320 is black or pseudo black. Further, the surface 201 is roughened (Ra is 50 micrometers or more, 100 micrometers or more) to increase the heat receiving area, and dimple formation by press molding or the like is exemplified. Thereby, the radiant heat absorbability on the surface 201 of the cover member 210 is increased. As a result, it is advantageous to increase the temperature rise performance of the cathode gas passing through the second passage 320. As a result, the combustibility in the combustion space 5 can be enhanced.

(Embodiment 8)
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIGS. 1 to 12 can be applied mutatis mutandis. In the following, different parts will be mainly described. It is preferable that at least the surface 201 of the cover member 210 forming the second passage 320 is subjected to a radiant heat reflection treatment so as to increase the reflectivity for reflecting the radiant heat from the stack 2 and / or the combustion flame 50. Specifically, the surface roughness Ra of the surface 201 is set to 20 μm or less, particularly 10 μm or less, and is preferably mirror-finished. Furthermore, the surface 201 is preferably white, gray, or whitish. Therefore, the surface 201 of the cover member 210 can efficiently reflect the radiant heat of the stack 2 and / or the combustion flame 50. Therefore, it is expected that the heat radiation of the stack 2 and / or the combustion flame 50 is suppressed, and the temperature of the stack 2 and / or the combustion flame 50 is maintained as high as possible.

(Embodiment 9)
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIGS. 1 to 12 can be applied mutatis mutandis. In the following, different parts will be mainly described. The passage forming portion 701k that forms the opposing passage 83 is heated by the stack 2 and the combustion flame 50 because it faces the side surface 2k of the stack 2 and the combustion flame 50. In this case, the passage forming portion 701k is preferably subjected to a radiant heat absorption process that increases the absorption rate for absorbing the radiant heat from the stack 2 and / or the combustion flame 50. For example, the surface of the passage forming portion 701k facing the stack 2 and / or the combustion flame 50 can be blackened or pseudo-blackened. In addition, the surface can be roughened (Ra: 50 micrometers or more, 100 micrometers or more). In this case, the temperature rise performance of the passage forming portion 701k is enhanced, which is advantageous in increasing the heating efficiency for heating the cathode gas flowing in the opposing passage 83.

  (Others) The present invention is not limited to the embodiment described above and shown in the drawings, and can be implemented with appropriate modifications within a range not departing from the gist. Two sets of stacks 2 are provided so as to sandwich the opposed passage 83 of the cathode gas passage 8, but the present invention is not limited to this, and one set of stacks 2 is provided adjacent to the opposed passage 83 of the cathode gas passage 8. It may be a structure. The stack 2 is formed by laminating a plurality of flat plate fuel cells in the thickness direction. However, the stack 2 is not limited thereto, and a stack may be formed by assembling a plurality of tube fuel cells. Even in this case, the stack extends in the longitudinal direction. According to the first embodiment described above, the reforming unit 42 and the evaporation unit 40 have a quadrangular cross section, but the present invention is not limited to this, and may be a circular cross section. Although the reforming unit 42 and the evaporation unit 40 for reforming the fuel material are integrated, the present invention is not limited thereto, and the evaporation unit 40 may be separated from the reforming unit 42. In this case, the evaporation unit may be heated by another heating source. The fuel cell is not limited to the solid oxide form, and may be a phosphate form or a molten carbonate form. In short, any fuel cell may be used as long as the reforming part is heated by a combustion flame. The following technical idea can be understood from the above description.

  [Additional Item 1] A reforming unit that reforms a fuel raw material to generate anode gas, an anode gas and a cathode gas generated in the reforming unit, and an anode off-gas discharged from the fuel cell for combustion. A fuel cell that heats the reforming unit with a combustion flame burned in space, an anode gas passage that supplies the anode gas generated in the reforming unit to the inside of the fuel cell, and a cathode gas that is supplied to the inside of the fuel cell A fuel cell device comprising a cathode gas passage and an exhaust gas passage for exhausting exhaust gas in a combustion space to the outside.

  [Additional Item 2] In Additional Item 1, the cathode gas passage has an opposing passage facing the fuel cell, and the opposing passage of the cathode gas passage is between the fuel cell and the opposing passage. A fuel cell device provided with a first passage through which cathode gas that has been supplied from and not flowed into the fuel cell flows toward the combustion space. The direction in which the cathode gas flows in the first passage and the direction in which the cathode gas flows in the opposite passage of the cathode gas passage are preferably opposite to each other.

  [Additional Item 3] In Additional Item 1, the cathode gas supplied from the opposite passage of the cathode gas passage and not flowing into the fuel cell is interposed between the fuel cell and the cover member. A fuel cell device provided with a second passage that flows toward the combustion space. The contact area where the fuel cell and the cover member are in direct contact is reduced, which can contribute to maintaining the temperature of the fuel cell.

  The present invention can be used in, for example, fuel cell systems for stationary use, vehicle use, electrical equipment use, and electronic equipment use.

  2 is a stack, 20 is a fuel cell, 21 is an anode, 22 is a cathode, 23 is an electrolyte, 25 is an anode gas passage, 3 is a substrate, 4 is a reformer, 40 is an evaporation section, 42 is a reforming section, 42s, 42m is a side surface of the reforming unit, 42u is an upper surface of the reforming unit, 42d is a lower surface of the reforming unit, 5 is a combustion space, 50 is a combustion flame, 6 is a heat insulating layer, 7 is an exhaust gas passage, and 7X is heat exchange. 701, 702 are passage forming members, 701k is a passage forming portion, 70 is a contact passage, 70f is a first contact passage, 70s is a second contact passage, 72 is an inlet, 73 is a downstream passage, and 74 is an outlet (exhaust gas). Outlet), 8 is a cathode gas passage, 81 is a first passage, 82 is a second passage, 83 is an opposing passage, 84 is an outlet, 87 is a communication passage, 88 is a cylinder, 210 is a cover member, 205 is a lower end, 206 is an upper end portion, 201 is a surface, 208 is a protrusion, 210 Cover body, 211 curved portion, 310 denotes a first passage, 320 shows a second passage.

Claims (3)

A reforming section for reforming the fuel material to generate anode gas;
A fuel cell that generates electricity with the anode gas and cathode gas generated in the reforming section and heats the reforming section with a combustion flame in which anode off-gas is burned in a combustion space;
An anode gas passage for supplying the anode gas generated in the reforming unit to the inside of the fuel cell;
A cathode gas passage for supplying a cathode gas to the cathode of the fuel cell;
An exhaust gas passage having a contact passage for bringing the combustion exhaust gas in the combustion space into contact with the reforming portion, and a downstream passage located downstream of the contact passage and toward the exhaust gas outlet;
Covering the combustion space in which the combustion flame burns, facilitating the flow of combustion exhaust gas in the combustion space to the contact passage, and passing the combustion exhaust gas in the combustion space through the contact passage And a cover member directed toward the downstream passage .
The combustion space has a first combustion space and a second combustion space so as to sandwich a passage forming member that forms the cathode gas passage,
The passage forming member that forms the cathode gas passage has a communication passage that connects the first combustion space and the second combustion space,
Wherein each of the first combustion space and the second combustion space, the fuel cell system that is arranged so as to sandwich between the passage forming member and the cover member. Oite to claim 1, wherein the cathode gas passage has a facing passage of heat from the fuel cell with facing to the fuel cell, between the facing passages and the fuel cell, the cathode gas passage There is provided a first passage through which the cathode gas supplied from the opposing passage and not flowing into the cathode of the fuel cell flows toward the combustion space, and the cathode gas flows in the first passage. A fuel cell device in which the cathode gas flows in opposite directions to the cathode gas passage in opposite directions. Oite to claim 1, wherein the cathode gas passage has a facing passage of heat from the fuel cell with facing to the fuel cell, between the cover member and the fuel cell, the cathode gas passage The fuel cell device is provided with a second passage through which the cathode gas that has been supplied from the opposing passage and has not flowed into the cathode of the fuel cell flows toward the combustion space.

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