Electrochemical reaction module

Abstract

To efficiently heat both a generator and a gas flow path.SOLUTION: An electrochemical reaction module includes an electrochemical reaction cell stack having a single cell with an anode, an electrolyte layer, and a cathode, a first gas flow space facing the anode, and a second gas flow space facing the cathode, a generator that generates a first gas to be supplied to the first gas flow space, a gas flow path through which a second gas to be supplied to the second gas flow space flows, a first combustor that combusts a combustion gas discharged from the electrochemical reaction cell stack and heats the generator with the combustion heat, and a second combustor that combusts the combustion gas and heats the gas flow path with the combustion heat, the second combustor being different from the first combustor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed herein relates to an electrochemical reaction module. [Background technology]

[0002] A known fuel cell system includes a fuel cell stack, a vaporizer and a reformer for generating fuel gas to be supplied to the fuel cell stack, a first combustor for heating the vaporizer, and a second combustor for heating the reformer. The first combustor generates heat required for the vaporizer to preheat the raw fuel gas and generate steam. The second combustor generates heat required for the reforming reaction of the raw fuel gas to be performed by the reformer. The combustion exhaust gas generated by the second combustor heats the air (oxidant gas) supplied to the fuel cell stack before being discharged outside the module case (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-31103 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above fuel cell system, if the thermal power of the combustor is increased in an attempt to sufficiently heat the fuel gas and oxidant gas, there is a concern that the heat will cause deformation or damage to the components that make up the reformer.

[0005] These issues are also common to modules that include electrolysis cell stacks that include multiple electrolysis cell units, which are constituent elements of solid oxide electrolysis cells (hereinafter referred to as "SOECs") that generate hydrogen using the electrolysis reaction of water. Furthermore, these issues are not limited to SOFCs or SOECs, but are also common to modules that include other types of electrochemical reaction cell stacks.

[0006] This specification discloses a technique that can solve the above-mentioned problems. [Means for solving the problem]

[0007] The technology disclosed in this specification can be realized, for example, in the following forms: (1) The electrochemical reaction module disclosed in this specification includes an electrochemical reaction cell stack including a unit cell including an anode, an electrolyte layer, and an air cathode, and having a first gas distribution space facing the anode and a second gas distribution space facing the air cathode, a generator that generates a first gas to be supplied to the first gas distribution space, a gas flow path through which a second gas to be supplied to the second gas distribution space flows, a first combustor that combusts a combustion gas discharged from the electrochemical reaction cell stack and heats the generator with the combustion heat, and a second combustor that combusts the combustion gas and heats the gas flow path with the combustion heat, the second combustor being different from the first combustor.

[0008] According to the above-described configuration, the generator and the gas flow path can be heated by different combustors, and therefore, compared to when one combustor heats both the generator and the gas flow path, it is easier to adjust the heating power for the generator and the gas flow path individually, and heating can be performed efficiently.

[0009] (2) In the electrochemical reaction module described in (1) above, the first combustor may have a first outlet from which the combustion gas is ejected, the second combustor may have a second outlet from which the combustion gas is ejected, and the opening area of the second outlet may be larger than the opening area of the first outlet.

[0010] Such a configuration is suitable when it is desired to start up the electrochemical cell stack in a short time (rapid start-up) while suppressing excessive temperature rise in the generator.

[0011] (3) The electrochemical reaction module described in (1) or (2) above may further include a gas supply passage that supplies the combustion gas to the first combustor and the second combustor, and the gas supply passage may be configured so that the amount of the combustion gas supplied to the second combustor is greater than that supplied to the first combustor.

[0012] This configuration is suitable for cases where it is desired to rapidly start up the electrochemical cell stack while suppressing excessive temperature rise in the generator.

[0013] (4) In the electrochemical reaction module described in (3) above, the gas supply path may include a main flow path, a first branch path branching from the main flow path and connected to the first combustor, and a second branch path branching from the main flow path and connected to the second combustor, and the flow path cross-sectional area of the second branch path may be larger than the flow path cross-sectional area of the first branch path.

[0014] According to this configuration, with a simple configuration, the amount of combustion gas supplied to the second combustor can be made greater than that to the first combustor.

[0015] (5) In the electrochemical reaction module described in (3) above, the gas supply path may include a main flow path, a first branch path branching from the main flow path and connected to the first combustor, and a second branch path branching from the main flow path and connected to the second combustor, and may further include a flow control mechanism disposed midway along the gas supply path and controlling the flow rate of the combustion gas flowing into the first branch path and the second branch path.

[0016] With this configuration, when starting up the electrochemical reaction module, the amount of combustion gas supplied to the second combustor is greater than that supplied to the first combustor, thereby preventing excessive temperature rise in the generator and enabling rapid startup of the electrochemical reaction cell stack. Furthermore, during operation of the electrochemical reaction module, the amount of combustion gas supplied to the first combustor can be made greater than that supplied to the second combustor as needed, enabling efficient power generation.

[0017] (6) In the electrochemical reaction module described in any one of (1) to (5) above, the gas flow path may include an upstream portion having an inlet for the second gas and a downstream portion having an outlet for the second gas, and the second combustor may be configured to heat the upstream portion.

[0018] According to this configuration, the second combustor is configured to heat the upstream portion of the gas flow path, i.e., the area into which the low-temperature second gas flows before being heated, thereby enabling the second gas to be heated efficiently.

[0019] (7) In the electrochemical reaction module described in (6) above, the upstream portion and the second combustor may be disposed above the generator and the first combustor.

[0020] With this configuration, the electrochemical reaction cell stack can be efficiently heated while preventing the generator from overheating.

[0021] The technology disclosed in this specification can be realized in various forms, for example, in the form of an electrochemical reaction cell stack and a manufacturing method thereof. [Brief explanation of the drawings]

[0022] [Figure 1] Configuration block diagram of a fuel cell module according to a first embodiment [Figure 2] 1 is a side view of a fuel cell module according to a first embodiment; [Figure 3] FIG. 1 is a perspective view of a fuel cell stack according to a first embodiment; [Figure 4] 4 is a cross-sectional view showing two adjacent electrochemical reaction units in the fuel cell stack of the first embodiment, taken along line IV-IV in FIG. 3. [Figure 5] 4 is a cross-sectional view showing two adjacent electrochemical reaction units in the fuel cell stack of the first embodiment, taken along line VV in FIG. 3; [Figure 6]A block diagram of a fuel cell module according to a second embodiment. [Figure 7] A configuration block diagram of a fuel cell module according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] A. First embodiment: A-1. Configuration of fuel cell module 10: A first embodiment will be described with reference to FIGS. 1 to 5. As shown in FIG. 1, a fuel cell module 10 (an example of an electrochemical reaction module) of this embodiment includes a fuel cell stack 100 (an example of an electrochemical reaction cell stack) and an auxiliary unit 400 provided outside the fuel cell stack 100. The auxiliary unit 400 includes a housing 410, a first combustor 420, a second combustor 425, a reformer 430 (an example of a generator), and an evaporator 440. The fuel cell stack 100 and the auxiliary unit 400 are surrounded by a heat insulating material (not shown), and another heat insulating material (not shown) is also provided between the fuel cell stack 100 and the auxiliary unit 400. This suppresses heat dissipation from the fuel cell stack 100.

[0024] (Fuel cell stack 100) The fuel cell stack 100 is used in a solid oxide fuel cell having an electrolyte layer 112 that includes a solid oxide.

[0025] 2 and 3, the fuel cell stack 100 includes a power generation block 101 (an example of a reaction block), a first terminal plate 240, a second terminal plate 250, two insulating plates 220, a first end plate 210, and a second end plate 270. The first end plate 210, one insulating plate 220, the first terminal plate 240, the power generation block 101, the second terminal plate 250, the other insulating plate 220, and the second end plate 270 have rectangular shapes of approximately the same size and are arranged in this order, stacked in a predetermined arrangement direction (the direction along the Z axis in FIG. 3).

[0026] As shown in Figure 3, the fuel cell stack 100 has bolt holes BH near each of its four corners, penetrating from the first end plate 210 to the second end plate 270. A bolt B is inserted into each bolt hole BH. A nut N is screwed onto both ends of each bolt B. These bolts B and nuts N fasten the members from the first end plate 210 to the second end plate 270 together.

[0027] The power generation block 101 is composed of a plurality of (seven in this embodiment) electrochemical reaction units 101U (hereinafter sometimes abbreviated as "reaction units 101U") arranged in a predetermined arrangement direction (the direction along the Z axis in FIGS. 4 and 5). Each electrochemical reaction unit 101U includes a single cell 110.

[0028] (Electrochemical reaction unit 101U) 4 and 5, the electrochemical reaction unit 101U includes a single cell 110, a single cell separator 120, a cathode frame 130, an anode frame 140, an cathode current collecting member 134, an anode current collecting member 144, and two interconnectors 150. One interconnector 150, the cathode frame 130, the single cell separator 120, the anode frame 140, and the other interconnector 150 have rectangular shapes of approximately the same size and are stacked in this order. The single cell 110 is supported by the single cell separator 120, the cathode current collecting member 134 is disposed between the single cell 110 and one of the interconnectors 150, and the anode current collecting member 144 is disposed between the single cell 110 and the other interconnector 150.

[0029] 4 and 5, the interconnector 150 is shared by two adjacent reaction units 101U. However, the reaction unit 101U located at one end of the multiple reaction units 101U does not have an interconnector 150 adjacent to the air electrode frame 130, and a first terminal plate 240 overlaps the air electrode frame 130. Furthermore, the reaction unit 101U located at the other end of the multiple reaction units 101U does not have an interconnector 150 adjacent to the fuel electrode frame 140, and a second terminal plate 250 overlaps the fuel electrode frame 140.

[0030] (single cell 110) The unit cell 110 includes an electrolyte layer 112, an air electrode 114, and an anode 116. As shown in Figures 4 and 5, the air electrode 114, the electrolyte layer 112, and the anode 116 are arranged in this order. The unit cell 110 of this embodiment is an anode-supported unit cell in which the other layers (electrolyte layer 112, air electrode 114) that make up the unit cell 110 are supported by the anode 116.

[0031] The electrolyte layer 112 is a rectangular, flat member having one surface (the upper surface in FIG. 4 ) on which the air electrode 114 is disposed and another surface (the lower surface in FIG. 4 ) parallel to the first surface on which the anode 116 is disposed. The electrolyte layer 112 is a layer containing a solid oxide (e.g., YSZ (yttria-stabilized zirconia)). The air electrode 114 is a layer having a rectangular shape smaller than that of the electrolyte layer 112 and containing, for example, a perovskite-type oxide (e.g., LSCF (lanthanum strontium cobalt iron oxide)). The anode 116 is a layer having a rectangular shape approximately the same size as the electrolyte layer 112 and containing, for example, Ni (nickel), a cermet made of Ni and ceramic particles, a Ni-based alloy, or the like.

[0032] (Single cell separator 120) 4 and 5, the single cell separator 120 is a rectangular frame-like member having a substantially rectangular through-hole 121 near the center, and is made of, for example, metal. The peripheral edge of the through-hole 121 in the single cell separator 120 is joined to the peripheral edge of one surface of the electrolyte layer 112 (the surface on which the air electrode 114 is disposed: the upper surface in FIG. 4) by a joint 124. The joint 124 is made of, for example, a brazing material (Ag brazing).

[0033] (Air electrode frame 130) As shown in FIGS. 4 and 5, the cathode frame 130 is a rectangular frame-like member having a substantially rectangular through-hole 131 near the center, and is made of, for example, insulating ceramics (mica, etc.).

[0034] (fuel electrode frame 140) As shown in FIGS. 4 and 5, the fuel electrode frame 140 is a rectangular frame-like member having a substantially rectangular through-hole 141 near the center, and is made of, for example, metal.

[0035] (Interconnector 150) The interconnector 150 is a rectangular plate-shaped member made of, for example, metal.

[0036] (Air electrode current collecting member 134 and fuel electrode current collecting member 144) The air electrode current collecting member 134 is a quadrangular prism-shaped member that connects the air electrode 114 and the interconnector 150, and a plurality of air electrode current collecting members 134 are arranged between the air electrode 114 and the interconnector 150. Each air electrode current collecting member 134 is made of, for example, ferritic stainless steel.

[0037] The anode current collecting member 144 is a member that connects the interconnector 150 and the anode 116, and is formed of a conductive material such as nickel, a nickel alloy, or stainless steel. As shown in Figures 4 and 5, the anode current collecting member 144 has an interconnector facing portion 146, an electrode facing portion 145 that is parallel to the interconnector facing portion 146, and a connecting portion 147 that connects the electrode facing portion 145 and the interconnector facing portion 146, and has an overall U-shape. The electrode facing portion 145 is in contact with the anode 116, and the interconnector facing portion 146 is in contact with the interconnector 150. A spacer 149 made of, for example, mica is disposed between the electrode facing portion 145 and the interconnector facing portion 146.

[0038] As described above, the interconnector 150 is shared by two adjacent reaction units 101U. More specifically, as shown in Figures 4 and 5, one interconnector 150 is electrically connected to the air electrode 114 of the unit cell 110 provided in one of the two adjacent reaction units 101U via the air electrode current collecting member 134, and is also electrically connected to the anode 116 of the unit cell 110 provided in the other of the two adjacent reaction units 101U via the anode current collecting member 144. This ensures electrical continuity between the two adjacent reaction units 101U.

[0039] However, as described above, the reaction unit 101U located at one end of the plurality of reaction units 101U does not have the interconnector 150 on the air electrode 114 side. The air electrode 114 included in this reaction unit 101U is connected to the first terminal plate 240 via the air electrode current collecting member 134. Furthermore, the reaction unit 101U located at the other end of the plurality of reaction units 101U does not have the interconnector 150 on the anode 116 side. The anode 116 included in this reaction unit 101U is connected to the second terminal plate 250 via the anode current collecting member 144.

[0040] (Air chamber 313 and fuel chamber 323) 4 and 5, the space partitioned by the single cell separator 120, the single cell 110, the air electrode frame 130, and the interconnector 150 faces the air electrode 114 and serves as an air chamber 313 (an example of a second gas flow space) through which the oxidant gas OG flows. The air electrode frame 130 separates the entire periphery of the air chamber 313 from the external space, and seals the gap between the single cell separator 120 and the interconnector 150, thereby preventing gas from leaking from the air chamber 313 to the external space.

[0041] The space partitioned by the single cell separator 120, the single cell 110, the fuel electrode frame 140, and the interconnector 150 faces the fuel electrode 116 and serves as a fuel chamber 323 (an example of a first gas flow space) through which fuel gas FG flows. The fuel electrode frame 140 partitions the entire periphery of the fuel chamber 323 from the external space, and seals the gap between the single cell separator 120 and the interconnector 150, thereby preventing gas from leaking from the fuel chamber 323 to the external space.

[0042] The single cell separator 120 separates the air chamber 313 and the fuel chamber 323, thereby preventing gas leakage (cross leakage) from the air electrode 114 side to the fuel electrode 116 side or from the fuel electrode 116 side to the air electrode 114 side around the single cell 110. The interconnector 150 also prevents gas leakage between adjacent reaction units 101U.

[0043] (First end plate 210) The first end plate 210 is made of a conductive material such as stainless steel, and has an overall rectangular flat plate shape.

[0044] (Second end plate 270) The second end plate 270 is made of a conductive material such as stainless steel, and has an overall rectangular flat plate shape.

[0045] (First terminal plate 240) The first terminal plate 240 is a rectangular plate-shaped member made of a conductive material such as stainless steel, etc. The first terminal plate 240 functions as the positive output terminal of the fuel cell stack 100.

[0046] (2nd terminal plate 250) The second terminal plate 250 is a rectangular plate-shaped member made of a conductive material such as stainless steel, etc. The second terminal plate 250 functions as the negative output terminal of the fuel cell stack 100.

[0047] (insulating plate 220) The insulating plate 220 is a rectangular plate-shaped member, and is made of an insulating material such as mica, alumina, silicon nitride, or zirconia.

[0048] 2, one insulating plate 220 is sandwiched between the first end plate 210 and the first terminal plate 240, and the other insulating plate 220 is sandwiched between the second end plate 270 and the second terminal plate 250. This insulates the first end plate 210 and the second end plate 270 from the components sandwiched between the two insulating plates 220 (the first terminal plate 240, the power generation block 101, and the second terminal plate 250).

[0049] (Manifolds 311, 312, 321, 322) 4 and 5, the fuel cell stack 100 has four holes that penetrate from the power generation block 101 to the second end plate 270. The four holes correspond to an oxidant gas supply manifold 311, an oxidant gas discharge manifold 312, a fuel gas supply manifold 321, and a fuel gas discharge manifold 322, respectively.

[0050] 4, the oxidant gas supply manifold 311 is a gas flow path that supplies the oxidant gas OG introduced from outside the fuel cell stack 100 to the air chamber 313 of each reaction unit 101U. The oxidant gas discharge manifold 312 is a gas flow path that discharges the oxidant off-gas OOG discharged from the air chamber 313 of each reaction unit 101U to the outside of the fuel cell stack 100. As the oxidant gas OG, for example, air is used.

[0051] 5, the fuel gas supply manifold 321 is a gas flow path that supplies fuel gas FG introduced from outside the fuel cell stack 100 to the fuel chamber 323 of each reaction unit 101U. The fuel gas discharge manifold 322 is a gas flow path that discharges fuel off-gas FOG discharged from the fuel chamber 323 of each reaction unit 101U to the outside of the fuel cell stack 100.

[0052] (Auxiliary equipment 400) The auxiliary device 400 is a device for supplying fuel gas FG obtained by reforming raw fuel gas RFG and air as oxidant gas OG to the fuel cell stack 100, and is arranged above the fuel cell stack 100 as shown in Fig. 2. As shown in Figs. 1 and 2, the auxiliary device 400 includes a housing 410, a first combustor 420, a second combustor 425, and a reformer 430 arranged inside the housing 410, and an evaporator 440 arranged above the housing 410.

[0053] In Figure 1, the flow of gases (raw fuel gas RFG, fuel gas FG, and fuel off-gas FOG) on the fuel electrode side is shown by dashed lines, the flow of gases (oxidant gas OG and oxidant off-gas OOG) on the air electrode side is shown by solid lines, and the flow of exhaust gas EG generated by the first combustor 420 is shown by dashed lines.

[0054] (Housing 410) 1, the housing 410 is a double container including an outer box 411 and an inner box 412 that is slightly smaller than the outer box 411 and is disposed inside the outer box 411. The outer box 411 and the inner box 412 are made of, for example, metal, and are sealed box-shaped containers. Inside the inner box 412, a second combustor 425, a reformer 430, and a first combustor 420 are housed in this order from top to bottom. The space between the outer box 411 and the inner box 412 forms an air flow path 413 (an example of a gas flow path), and heat transfer fins 414 are disposed inside the air flow path 413.

[0055] The outer box 411 is connected to an air supply pipe 451 that supplies oxidant gas OG (air) to the inside of the air flow path 413, and an oxidant gas supply pipe 452 that communicates with the oxidant gas supply manifold 311 and supplies the oxidant gas OG that has passed through the inside of the air flow path 413 to the fuel cell stack 100. The inner box 412 is connected to an exhaust gas relay pipe 481 that sends the exhaust gas EG generated by the combustors 420, 425 to the evaporator 440.

[0056] The top wall of the outer box 411 has an opening to which the air supply pipe 451 is connected, and this opening is an inlet 413IN of the oxidant gas OG into the air flow path 413. The bottom wall of the outer box 411 has an opening to which the oxidant gas supply pipe 452 is connected, and this opening is an outlet 413OUT of the oxidant gas from the air flow path 413. The air flow path 413 includes an upstream section 413UP and a downstream section 413UN. The upstream section 413UP is a space between the top wall of the outer box 411, which has the inlet 413IN, and the top wall of the inner box 412, and is disposed above the second combustor 425. The downstream section 413UN is a space between the bottom wall of the outer box 411, which has the outlet 413OUT, and the bottom wall of the inner box 412.

[0057] (Evaporator 440) The evaporator 440 is a device that evaporates the reforming water RW to generate steam, mixes this steam with the raw fuel gas RFG, and supplies it to the reformer 430. The evaporator 440 is connected to a reforming water supply pipe 471 for introducing the reforming water RW into the interior, a raw fuel gas supply pipe 461 for introducing the raw fuel gas RFG into the interior, a mixed gas supply pipe 462 that communicates with the internal space of the reformer 430 and supplies the mixed gas from the evaporator 440 to the reformer 430, and an exhaust gas discharge pipe 482 for discharging the exhaust gas EG to the outside after being used to heat the reforming water RW.

[0058] (Reformer 430) The reformer 430 is a device for reforming the raw fuel gas RFG mixed with steam supplied from the evaporator 440 to generate hydrogen-rich fuel gas FG. A reforming catalyst for promoting the reforming reaction may be disposed inside the reformer 430. A fuel gas supply pipe 463 is connected to the reformer 430, which communicates with the fuel gas supply manifold 321 and supplies the fuel gas FG to the fuel cell stack 100.

[0059] (First combustor 420) The first combustor 420 mixes and combusts the fuel off-gas FOG and the oxidant off-gas OOG that are not used in the power generation reaction by the fuel cell stack 100 and are discharged, generating exhaust gas EG. The first combustor 420 mainly heats the reformer 430. A catalyst for promoting the combustion of the oxidant off-gas OOG and the fuel off-gas FOG may be disposed inside the first combustor 420. The first combustor 420 is connected to an oxidant gas discharge pipe 453 that communicates with the oxidant gas discharge manifold 312 and a fuel gas discharge pipe 464 (an example of a gas supply path) that communicates with the fuel gas discharge manifold 322. The first combustor 420 has a first ejection surface 421 facing the reformer 430 and a plurality of first ejection ports 422 that open to the first ejection surface 421. The first combustor 420 is disposed on the bottom wall of the inner box 412.

[0060] (Second combustor 425) The second combustor 425 mixes and combusts the fuel off-gas FOG and the oxidant off-gas OOG that are discharged without being used in the power generation reaction by the fuel cell stack 100, generating exhaust gas EG. The second combustor 425 mainly heats the upstream portion 413UP of the air flow path 413. A catalyst that promotes the combustion of the oxidant off-gas OOG and the fuel off-gas FOG may be disposed inside the second combustor 425. An oxidant gas discharge pipe 453 that communicates with the oxidant gas discharge manifold 312 and a fuel gas discharge pipe 464 that communicates with the fuel gas discharge manifold 322 are connected to the second combustor 425.

[0061] The second combustor 425 has a second jetting surface 426 facing the upstream portion 413UP and a plurality of second jetting ports 427 opening on the second jetting surface 426. The opening area of the second jetting ports 427 is larger than the opening area of the first jetting ports 422. In this specification, the "opening area" of the first jetting ports refers to the total opening area of all the first jetting ports 422 when the first combustor 420 has a plurality of first jetting ports 422. The "opening area" of the second jetting ports refers to the total opening area of all the second jetting ports 427 when the second combustor 425 has a plurality of second jetting ports 427.

[0062] The second combustor 425 is supported by a support plate 490 extending inward from the side wall of the inner box 412 and by a fuel gas discharge pipe 464 .

[0063] (Fuel gas exhaust pipe 464) The fuel gas discharge pipe 464 includes a main flow path 465 connected to the fuel gas discharge manifold 322, a first branch path 466 branching from the main flow path 465, and a second branch path 467 branching from the main flow path 465. The first branch path 466 is connected to the first combustor 420. The second branch path 467 is connected to the second combustor 425. The second branch path 467 has a larger flow path cross-sectional area than the first branch path 466. In this specification, the "flow path cross-sectional area" of the first branch path refers to the cross-sectional area of the narrowest portion of the first branch path when the cross-sectional area of the first branch path is not constant, for example, when the diameter of the pipe constituting the first branch path is not constant. The same applies to the "flow path cross-sectional area" of the second branch path.

[0064] A-2. Operation of the fuel cell module 10 When the fuel cell module 10 is started up, as shown in FIG. 1, oxidant gas OG flows through the air supply pipe 451 and into the air flow path 413 from the inlet 413IN, flows through the air flow path 413, and exits from the outlet 413OUT. The oxidant gas OG is then supplied to the air chamber 313 through the oxidant gas supply pipe 452 and the oxidant gas supply manifold 311. Furthermore, raw fuel gas RFG (e.g., city gas) is supplied to the evaporator 440 through the raw fuel gas supply pipe 461, and reforming water RW is supplied through the reforming water supply pipe 471. The raw fuel gas RFG passes through the evaporator 440 and is supplied to the reformer 430. At the beginning of startup of the fuel cell module 10, the temperature of the reformer 430 is low, so a reaction to reform the raw fuel gas RFG does not occur. The raw fuel gas RFG that has passed through the reformer 430 is supplied to the fuel chamber 323 through the fuel gas supply pipe 463 and the fuel gas supply manifold 321.

[0065] In the early stages of startup of the fuel cell module 10, no power generation reaction occurs in the unit cells 110. Therefore, the oxidant gas OG supplied to the air chamber 313 passes directly through the oxidant gas discharge manifold 312 and the oxidant gas discharge piping 453 and is supplied to the first combustor 420 and the second combustor 425. In addition, the raw fuel gas RFG (an example of combustion gas) supplied to the fuel chamber 323 passes directly through the fuel gas discharge manifold 322 and the fuel gas discharge piping 464 and is supplied to the first combustor 420 and the second combustor 425.

[0066] The oxidant gas OG supplied to the first combustor 420 is ejected toward the internal space of the inner box 412. The raw fuel gas RFG supplied to the first combustor 420 is ejected from the first outlet 422 toward the internal space of the inner box 412. The ejected raw fuel gas RFG is ignited by an ignition device (not shown) and burns together with the oxidant gas OG. The reformer 430 is heated by the combustion heat generated by this combustion. Furthermore, the oxidant gas OG supplied to the second combustor 425 is ejected toward the internal space of the inner box 412. The raw fuel gas RFG supplied to the second combustor 425 is ejected from the second outlet 427 toward the internal space of the inner box 412. The ejected raw fuel gas RFG is ignited by an ignition device (not shown) and burns together with the oxidant gas OG. The upstream portion 413UP of the air flow path 413 is heated by the combustion heat generated by this combustion. The high-temperature exhaust gas EG generated by the combustion of the raw fuel gas RFG in the two combustors 420, 425 is supplied to the evaporator 440 through the exhaust gas relay pipe 481 and is used to heat the reforming water RW to generate steam.

[0067] When water vapor begins to be generated in the evaporator 440, this water vapor is mixed with the raw fuel gas RFG. The mixed gas of water vapor and raw fuel gas RFG is supplied to the reformer 430 through the mixed gas supply pipe 462. When the temperature of the reformer 430 is sufficiently increased by the combustion heat generated from the first combustor 420, the raw fuel gas RFG comes into contact with the reforming catalyst inside the reformer 430, causing a steam reforming reaction and generating hydrogen-rich fuel gas FG. The generated fuel gas FG is supplied to the fuel chamber 323 through the fuel gas supply pipe 463 and the fuel gas supply manifold 321.

[0068] Furthermore, while flowing through the air flow path 413, the oxidant gas OG is heated by the heat of combustion generated in the second combustor 425 and is supplied to the air chamber 313 through the oxidant gas supply pipe 452 and the oxidant gas supply manifold 311. The fuel cell stack 100 is heated by the high-temperature oxidant gas OG being supplied to the interior.

[0069] When the temperature of the fuel cell stack 100 rises sufficiently, power is generated in the unit cells 110 through an electrochemical reaction between the oxidant gas OG and the fuel gas FG. This power generation reaction is an exothermic reaction. As described above, the interconnector 150 is shared by two adjacent reaction units 101U, and the interconnector 150 ensures electrical continuity between the two adjacent reaction units 101U. In other words, the multiple reaction units 101U included in the fuel cell stack 100 are electrically connected in series. Furthermore, a first terminal plate 240 is electrically connected to the reaction unit 101U located at one end of the multiple reaction units 101U, and a second terminal plate 250 is electrically connected to the reaction unit 101U located at the other end. As a result, electrical energy generated in each reaction unit 101U is extracted from the second terminal plate 250, which functions as an output terminal of the fuel cell stack 100. Since SOFCs generate electricity at relatively high temperatures (e.g., 700°C to 1000°C), after startup, the fuel cell stack 100 may be heated by a heater (not shown) until the high temperature can be maintained using the heat generated by power generation.

[0070] The oxidant off-gas OOG discharged from the air chamber 313 to the oxidant gas discharge manifold 312 is supplied to the first combustor 420 and the second combustor 425 through the oxidant gas discharge pipe 453. In addition, the fuel off-gas FOG (an example of combustion gas) discharged from the fuel chamber 323 to the fuel gas discharge manifold 322 is supplied to the first combustor 420 and the second combustor 425 through the fuel gas discharge pipe 464.

[0071] The oxidant off-gas OOG supplied to the first combustor 420 is ejected toward the internal space of the inner box 412. The fuel off-gas FOG supplied to the first combustor 420 is ejected from the first ejection port 422 toward the internal space of the inner box 412. The ejected fuel off-gas FOG combusts together with the oxidant off-gas OOG. The reformer 430 is heated by the combustion heat generated by this combustion. Furthermore, the oxidant gas OG supplied to the second combustor 425 is ejected toward the internal space of the inner box 412. The fuel off-gas FOG supplied to the second combustor 425 is ejected from the second ejection port 427 toward the internal space of the inner box 412. The ejected fuel off-gas FOG combusts together with the oxidant gas OG. The combustion heat generated by this combustion heats the upstream portion 413UP of the air flow path 413. The high-temperature exhaust gas EG generated by the combustion of fuel off-gas FOG in the two combustors 420, 425 is supplied to the evaporator 440 through the exhaust gas relay pipe 481 and is used to heat the reforming water RW to generate steam.

[0072] Here, if the thermal power of the combustor is increased in an attempt to sufficiently heat the fuel gas and oxidant gas, there is a concern that the heat may cause deformation or damage to the components that make up the reformer, or may deteriorate the reforming catalyst, resulting in a decrease in reforming efficiency. In particular, at the initial stage of startup of the fuel cell module, in order to heat the fuel cell stack to a temperature at which it can generate electricity in a short time, it is necessary to sufficiently heat the oxidant gas before supplying it to the fuel cell stack. For this reason, it is necessary to increase the thermal power of the combustor to a certain extent, which makes the above problem more pronounced.

[0073] In this embodiment, the first combustor 420 heats the reformer 430, and the second combustor 425 heats the upstream portion 413UP of the air flow path 413. With this configuration, it is easier to adjust the heating power for the reformer 430 and the air flow path 413 individually, compared to when a single combustor heats both the reformer 430 and the air flow path 413. That is, the second combustor 425 can have a large heating power so that it can sufficiently heat the oxidant gas OG and heat the fuel cell stack 100 to a temperature at which power can be generated in a short time. On the other hand, the first combustor 420 can have a smaller heating power than the second combustor 425 so that deformation or damage to components constituting the reformer and deterioration of the reforming catalyst can be suppressed.

[0074] The second combustor 425 is configured to heat the upstream section 413UP of the air flow path 413, i.e., the region into which low-temperature oxidant gas OG flows before being heated. Furthermore, the inlet 413IN of the air flow path 413 is located on the top wall of the outer box 411, and the outlet 413OUT is located on the bottom wall of the outer box 411. That is, the upstream section 413UP of the air flow path 413 is located on the upper side, and the downstream section 413UN is located on the lower side, and the oxidant gas OG flows from top to bottom inside the air flow path 413. The upstream section 413UP and the second combustor 425 are located above the reformer 430 and the first combustor 420. Inside the housing 410, the high-temperature exhaust gas EG moves upward by convection. Therefore, the upstream section 413UP is heated not only by the heat from the second combustor 425, but also by the high-temperature exhaust gas EG that has moved upward. This allows the oxidant gas OG to be heated sufficiently, and the fuel cell stack 100 to a temperature at which electricity can be generated in a short time.

[0075] The opening area of the second outlet 427 is larger than the opening area of the first outlet 422. Furthermore, the flow path cross-sectional area of the second branch path 467 is larger than the flow path cross-sectional area of the first branch path 466. The fuel off-gas FOG that flows from the fuel gas discharge manifold 322 into the main flow path 465 is distributed more to the second branch path 467 than to the first branch path 466. In other words, the amount of fuel off-gas FOG supplied to the second combustor 425 is greater than that of the first combustor 420. This allows the thermal power of the second combustor 425 to be greater than that of the first combustor 420, and enables the fuel cell stack 100 to be efficiently heated while suppressing an excessive temperature rise in the reformer 430.

[0076] A-3. Advantages of this embodiment: As described above, the fuel cell module 10 of this embodiment includes the fuel cell stack 100, the reformer 430, the air flow path 413, the first combustor 420, and the second combustor 425. The fuel cell stack 100 includes the unit cell 110, which includes the anode 116, the electrolyte layer 112, and the cathode 114. The fuel cell stack 100 further includes a fuel chamber 323 facing the anode 116 and an air chamber 313 facing the cathode 114. The reformer 430 generates a fuel gas FG to be supplied to the fuel chamber 323. The air flow path 413 allows an oxidant gas OG to be supplied to the air chamber 313 to flow through. The first combustor 420 combusts the raw fuel gas RFG or the fuel off-gas FOG discharged from the fuel cell stack 100, and heats the reformer 430 with the combustion heat. The second combustor 425 is a combustor different from the first combustor 420, and combusts the raw fuel gas RFG or the fuel off-gas FOG discharged from the fuel cell stack 100, and heats the air flow path 413 with the combustion heat.

[0077] According to the above configuration, the reformer 430 and the air flow path 413 can be heated by different combustors 420, 425, respectively. Therefore, compared to the case where one combustor heats both the reformer 430 and the air flow path 413, it is easier to adjust the heating power for the reformer 430 and the air flow path 413 individually, and heating can be performed more efficiently.

[0078] The first combustor 420 has a first outlet 422 from which the raw fuel gas RFG or the fuel off-gas FOG is ejected. The second combustor 425 has a second outlet 427 from which the raw fuel gas RFG or the fuel off-gas FOG is ejected. The opening area of the second outlet 427 is larger than the opening area of the first outlet 422. This configuration is suitable for the case where rapid startup of the fuel cell stack 100 is desired while suppressing excessive temperature rise of the reformer 430.

[0079] The fuel cell module 10 further includes a fuel gas discharge pipe 464 that supplies raw fuel gas RFG or fuel off-gas FOG to the first combustor 420 and the second combustor 425. The fuel gas discharge pipe 464 is configured so that the amount of raw fuel gas RFG or fuel off-gas FOG supplied to the second combustor 425 is greater than that supplied to the first combustor 420. This configuration is suitable for the case where rapid startup of the fuel cell stack 100 is desired while suppressing excessive temperature rise in the generator.

[0080] The fuel gas discharge pipe 464 includes a main flow path 465, a first branched path 466 branching from the main flow path 465 and connected to the first combustor 420, and a second branched path 467 branching from the main flow path 465 and connected to the second combustor 425. The cross-sectional area of the second branched path 467 is larger than the cross-sectional area of the first branched path 466. With this simple configuration, it is possible to increase the amount of raw fuel gas RFG or fuel off-gas FOG supplied to the second combustor 425 compared to the first combustor 420.

[0081] The air flow path 413 includes an upstream section 413UP having an inlet 413IN for the oxidant gas OG, and a downstream section 413UN having an outlet 413OUT for the oxidant gas OG. The second combustor 425 is configured to heat the upstream section 413UP. With this configuration, the second combustor 425 is configured to heat the region into which the low-temperature oxidant gas OG flows before being heated, thereby enabling the oxidant gas OG to be heated efficiently.

[0082] The upstream section 413UP and the second combustor 425 are disposed above the reformer 430 and the first combustor 420. With this configuration, the fuel cell stack 100 can be efficiently heated while preventing the reformer 430 from overheating.

[0083] B. Second embodiment The second embodiment will be described with reference to FIG. 6 . Similar to the first embodiment, the fuel cell module 10B of this embodiment includes an auxiliary unit 400B. The auxiliary unit 400B includes a housing 410. Inside the housing 410, a second combustor 425, a reformer 430, and a first combustor 420 are housed in this order from top to bottom. A heat insulator 500 is disposed on the top surface of the reformer 430, and the second combustor 425 is disposed on the top surface of the heat insulator 500. That is, the second combustor 425 is supported by the reformer 430, and the heat insulator 500 is disposed between the second combustor 425 and the reformer 430, thereby preventing radiant heat from the second combustor 425 from being transmitted to the reformer 430. This configuration can reduce the number of components for supporting the second combustor 425 while preventing the reformer 430 from overheating. The heat insulating material 500 may be disposed over the entire top surface of the reformer 430, or may be disposed over a portion of the top surface.

[0084] Similar to the first embodiment, the fuel cell module 10B includes a fuel gas discharge pipe 464B. The fuel gas discharge pipe 464B includes a main flow path 465B connected to the fuel gas discharge manifold 322, a first branch path 466B branching from the main flow path 465B, and a second branch path 467B branching from the main flow path 465B. The first branch path 466B is connected to the first combustor 420. The second branch path 467B is connected to the second combustor 425. The first branch path 466B and the second branch path 467B may have the same or different flow path cross-sectional areas. A first flow control valve 511 (an example of a flow control mechanism) is disposed midway along the first branch path 466B, and a second flow control valve 512 (an example of a flow control mechanism) is disposed midway along the second branch path 467B. The first flow control valve 511 may be a valve that can adjust the flow rate without limit by controlling the opening of the valve, such as a linear solenoid valve, a proportional valve, or a pressure control valve. The same applies to the second flow control valve 512. The two flow control valves 511 and 512 adjust the distribution amount of the raw fuel gas RFG or the fuel off-gas FOG that is flowed to the first branch path 466B and the second branch path 467B.

[0085] The other configurations are the same as those in the first embodiment, so the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

[0086] According to the fuel cell module 10B of this embodiment, the reformer 430 and the air flow path 413 can be heated efficiently, as in the first embodiment.

[0087] The fuel cell module 10B also includes flow control valves 511, 512 that are arranged midway along the fuel gas discharge pipe 464B and control the flow rates of the raw fuel gas RFG or fuel off-gas FOG that flow into the first branch path 466B and the second branch path 467B. At the start-up of the fuel cell module 10B, the amount of raw fuel gas RFG supplied to the second combustor 425 is greater than that supplied to the first combustor 420, thereby preventing the reformer 430 from overheating and enabling the fuel cell stack 100 to start up quickly. Meanwhile, during operation of the fuel cell module 10B, the amount of fuel off-gas FOG supplied to the first combustor 420 is greater than that supplied to the second combustor 425, as needed, enabling efficient power generation.

[0088] C. Third embodiment The third embodiment will be described with reference to Fig. 7. Similar to the first embodiment, the fuel cell module 10C of this embodiment includes an auxiliary unit 400C. The auxiliary unit 400C includes a first housing 410C that houses a second combustor 425, and a second housing 416 that houses a first combustor 420 and a reformer 430.

[0089] Similar to the housing 410 of the first embodiment, the first housing 410C is a double container including an outer box 411C and an inner box 412C that is one size smaller than the outer box 411C and is placed inside the outer box 411C. The space between the outer box 411C and the inner box 412C serves as an air flow path 413C (an example of a gas flow path).

[0090] The second housing 416 is a sealed box-shaped container made of, for example, metal. The second housing 416 is disposed on top of the outer box 411C. Inside the second housing 416, the reformer 430 and the first combustor 420 are accommodated side by side from top to bottom.

[0091] An air supply pipe 451 that supplies oxidant gas OG to the inside of the air flow path 413C and an oxidant gas supply pipe 452 that communicates with the oxidant gas supply manifold 311 and supplies the oxidant gas OG that has passed through the inside of the air flow path 413C to the fuel cell stack 100 are connected to the outer box 411C. An exhaust gas relay pipe 481 that sends the exhaust gas EG generated by the combustors 420, 425 to the evaporator 440 is connected to the inner box 412C and the second housing 416.

[0092] The other configurations are the same as those in the first embodiment, so the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

[0093] According to the fuel cell module 10C of this embodiment, the reformer 430 and the air flow path 413 can be heated efficiently, as in the first embodiment.

[0094] Furthermore, the first combustor 420 and the reformer 430 heated thereby are completely separated from the second combustor 425 and the air flow path 413C heated thereby by the two housings 410C, 416. This makes it easier to separately adjust the heating of the reformer 430 and the heating of the oxidant gas OG flowing inside the air flow path 413C.

[0095] D. Variations (1) In the first and second embodiments, the second combustor 425, the reformer 430, and the first combustor 420 were arranged in this order from top to bottom inside the inner box 412. However, the arrangement of the first combustor, the second combustor, and the generator is not limited to that of the above embodiments. For example, the first combustor and the second combustor may be arranged side by side, and the reformer may be arranged adjacent to the first combustor. (2) In the first and second embodiments, the second combustor 425 heated the upstream portion 413UP of the air flow path 413, but the second combustor may also heat the downstream portion of the gas flow path or the intermediate portion between the upstream and downstream portions. (3) In the second embodiment, a heat insulating material is arranged between the reformer 430 and the second combustor 425, but a heat insulating material does not have to be arranged between the generator and the second combustor. (4) In the second embodiment, the first flow control valve 511 (an example of a flow control mechanism) is arranged midway along the first branch path 466B, and the second flow control valve 512 (an example of a flow control mechanism) is arranged midway along the second branch path 467B. However, for example, the flow control mechanism may be arranged at the branch position of the main flow path 465 to the first branch path 466B and the second branch path 467B, and may be a three-way valve capable of proportional control, and this three-way valve may control the flow rate of the combustion gas to be greater in the second branch path than in the first branch path. (5) In the above embodiment, the opening area of the second ejection port 427 was larger than the opening area of the first ejection port 422. However, for example, the opening area of the second ejection port may be equal to the opening area of the first ejection port. (6) In the third embodiment, the second housing 416 is disposed on top of the first housing 410C, but for example, the first housing may be disposed on top of the second housing, or the first and second housings may be disposed side by side. Also, the first and second housings do not have to be in contact with each other. (7) The above configuration can also be applied to cell stacks used in other types of fuel cells, such as polymer electrolyte fuel cells (PEFCs), phosphoric acid fuel cells (PAFCs), and molten carbonate fuel cells (MCFCs), or to electrolysis cell stacks that include electrolysis cell units, which are constituent elements of solid oxide electrolysis cells (SOECs), as single cells. For example, in the case of a module that includes an SOEC as an electrochemical reaction cell stack, the evaporator and the water vapor generated by the evaporator correspond to the generator and the first gas, respectively, and combustion gas is supplied to the combustor from the outside. [Explanation of symbols]

[0096] 10, 10B, 10C: fuel cell module (electrochemical reaction module) 100: fuel cell stack (electrochemical reaction cell stack) 101: power generation block (reaction block) 101U: electrochemical reaction unit 110: single cell 112: electrolyte layer 114: air electrode 116: fuel electrode 120: single cell separator 121: through hole 124: joint 130: air electrode frame 131: through hole 134: air electrode current collecting member 140: fuel electrode frame 141: through hole 144: fuel electrode current collecting member 145: electrode opposing portion 146: interconnector opposing portion 147: connecting portion 149: spacer 150: interconnector 210: first end plate 220: insulating plate 240: first terminal plate 250: second terminal plate 270: second end plate 311: Oxidant gas supply manifold 312: Oxidant gas discharge manifold 313: Air chamber (second gas flow space) 321: Fuel gas supply manifold 322: Fuel gas discharge manifold 323: Fuel chamber (first gas flow space) 400, 400B, 400C: Auxiliary device 410: Housing 410C: First housing 411, 411C: Outer box 412, 412C: Inner box 413, 413C: Air flow path (gas flow path) 413IN: Inlet 413OUT: Outlet 413UN: Downstream portion 413UP: Upstream portion 414: Heat transfer fin 416: Second housing 420: First combustor 421: First ejection surface 422: First ejection port 425: Second combustor 426: Second ejection surface 427: Second nozzle 430: Reformer (generator) 440: Evaporator 451: Air supply pipe 452: Oxidant gas supply pipe 453: Oxidant gas discharge pipe 461: Raw fuel gas supply pipe 462: Mixed gas supply pipe 463: Fuel gas supply pipe 464, 464B: Fuel gas discharge pipe (gas supply path) 465, 465B: Main flow path 466, 466B: First branch path 467, 467B: Second branch path 471: Reforming water supply pipe 481: Exhaust gas relay pipe 482: Exhaust gas discharge pipe 490: Support plate 500: Heat insulating material 511: First flow control valve 512: Second flow control valve B: Bolt BH: Bolt hole EG: Exhaust gas FG: Fuel gas FOG: Fuel off-gas (combustion gas) N: Nut OG: Oxidant gas OOG: Oxidant off-gasRFG: Raw fuel gas (gas for combustion) RW: Reformed water

Claims

1. an electrochemical reaction cell stack including a single cell including an anode, an electrolyte layer, and an air cathode, and having a first gas distribution space facing the anode and a second gas distribution space facing the air cathode; a generator that generates a first gas to be supplied to the first gas flow space; a gas flow path through which a second gas flows to be supplied to the second gas flow space; a first combustor that combusts combustion gas discharged from the electrochemical reaction cell stack and heats the generator with the combustion heat; a second combustor that combusts the combustion gas and heats the gas flow path with the combustion heat, the second combustor being different from the first combustor; Equipped with Electrochemical reaction module.

2. the first combustor has a first outlet through which the combustion gas is ejected, the second combustor has a second outlet through which the combustion gas is ejected, The opening area of the second jetting port is larger than the opening area of the first jetting port. The electrochemical reaction module of claim 1 .

3. a gas supply passage for supplying the combustion gas to the first combustor and the second combustor; The gas supply passage is configured so that an amount of the combustion gas supplied to the second combustor is greater than that supplied to the first combustor. The electrochemical reaction module according to claim 1 or 2.

4. The gas supply path The main channel and a first branch passage branching from the main passage and connected to the first combustor; a second branch passage branching from the main passage and connected to the second combustor; Equipped with The cross-sectional area of the second branch path is larger than the cross-sectional area of the first branch path. The electrochemical reaction module according to claim 3 .

5. The gas supply path The main channel and a first branch passage branching from the main passage and connected to the first combustor; a second branch passage branching from the main passage and connected to the second combustor; Equipped with a flow rate control mechanism disposed in the gas supply path and configured to control the flow rate of the combustion gas flowing into the first branch path and the second branch path; Further provided with The electrochemical reaction module according to claim 3 .

6. The gas flow path an upstream portion having an inlet for the second gas; a downstream portion having an outlet for the second gas; Equipped with the second combustor is configured to heat the upstream portion; The electrochemical reaction module according to claim 1 or 2.

7. the upstream portion and the second combustor are disposed above the generator and the first combustor; The electrochemical reaction module according to claim 6 .

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