Electrochemical cell stack, electrochemical cell cartridge and electrochemical cell module including the same, and manufacturing method thereof, fuel cell stack, and co-electrolysis cell stack

Abstract

To provide an electrochemical cell stack that can preheat supplied gas to a desired temperature even when there is a temperature drop due to endothermic reactions occurring before the gas reaches an electrochemical unit cell.SOLUTION: An electrochemical cell stack 101 according to the present disclosure includes a raw material gas inlet heat exchanger 13, located on the raw material gas supply port 11 side of a reaction portion 10 having an electrochemical single cell 105 formed by stacking a first electrode, a solid electrolyte membrane, and a second electrode in that order, for heat exchange between the raw material gas and an oxidizing gas supplied to the second electrode side, and a product gas outlet heat exchanger 14, located on the product gas exhaust port 12 side of the reaction portion 10, for heat exchange between the product gas and the oxidizing gas supplied to the second electrode side, and the heat transfer area of the raw material gas inlet heat exchanger 13 is the same as or larger than the heat transfer area of the product gas outlet heat exchanger 14.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electrochemical cell stack, an electrochemical cell cartridge and an electrochemical cell module including the same, as well as methods for manufacturing the same, a fuel cell stack, and a co-electrolysis cell stack. [Background technology]

[0002] Fuel cells, which generate electricity through an electrochemical reaction between fuel gas and oxidizing gas, have excellent power generation efficiency and environmental friendliness. Among these, solid oxide fuel cells (SOFCs) use ceramics such as yttria-stabilized zirconia as the electrolyte.

[0003] Patent Document 1 discloses a cylindrical horizontally striped SOFC. The cell stack of the cylindrical horizontally striped SOFC has a porous substrate tube and electrochemical unit cells, each having a fuel electrode, a solid electrolyte, and an air electrode stacked in this order on the outer circumferential surface of the substrate tube. A plurality of electrochemical unit cells are formed along the longitudinal direction in the center of the substrate tube, and adjacent electrochemical unit cells are electrically connected via interconnectors.

[0004] In the cell stack, a fuel gas is introduced into the substrate tube, and an oxidizing gas is circulated outside the substrate tube, and power is generated by electrochemically reacting the fuel gas with the oxidizing gas in a high-temperature atmosphere of approximately 700°C to 1000°C. Examples of fuel gases that can be used include hydrogen, city gas, natural gas, petroleum, methanol, gasification gas produced from carbon-containing raw materials using gasification equipment, and biogas made from biomass.

[0005] Furthermore, electrolysis cells, which produce hydrogen and oxygen by electrochemically decomposing water, are a hydrogen production method that does not involve carbon dioxide emissions and has excellent environmental properties. Among these, solid oxide electrolysis cells (SOECs) use ceramics such as yttria-stabilized zirconia as the electrolyte, and can produce hydrogen more efficiently than other electrolysis cells because they use high-temperature steam as a feedstock and can utilize the heat of the steam as part of the energy for electrolysis. Furthermore, for the purpose of decarbonization, co-electrolysis is also possible, using carbon dioxide (CO2) as a feedstock and electrolytic hydrogen as a reducing agent to directly produce carbon monoxide (CO).

[0006] SOFCs and SOECs are collectively called solid oxide electrochemical cells. Some solid oxide electrochemical cells can be used as reversible solid oxide electrochemical cells (RSOCs), which have the power generation function as a fuel cell and the function of producing hydrogen and oxygen through a reverse reaction when supplied with external electricity and high-temperature steam. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2013-161637 A (paragraphs

[0002] to

[0004] ) Summary of the Invention [Problem to be solved by the invention]

[0008] SOFCs generate power in a high-temperature atmosphere of 700°C to 1000°C, so the fuel gas and oxidant gas need to be preheated when they are supplied to the cell stack.

[0009] On the other hand, when fuel gas is supplied to an SOFC cell stack, an endothermic reaction occurs. If the metallic material in the gas preheating area on the inlet side of the cell stack contains catalytic components such as nickel, this endothermic reaction occurs significantly before the fuel gas reaches the electrochemical unit cells or in the electrochemical unit cells on the inlet side, causing the temperature of the fuel gas on the inlet side to drop. If the fuel gas temperature is low, the internal resistance of the SOFC unit cells increases, and the voltage that can be extracted externally decreases. This reduces the power (current x voltage) that can be extracted from the SOFC cell stack.

[0010] On the other hand, this issue can also arise when supplying hydrogen-containing gas to a co-electrolytic cell stack. Hydrogen is added to the feed gases of water vapor and carbon dioxide to prevent oxidation of metal materials such as iron and nickel.

[0011] For example, when a gas containing carbon dioxide and hydrogen is supplied as a feed gas to a co-electrolysis cell stack, an endothermic reaction called the reverse water-gas shift reaction occurs in the gas preheating region on the gas inlet side of the co-electrolysis cell stack.

[0012] Solid oxide electrochemical cells, which use ceramics such as yttria-stabilized zirconia as the electrolyte, must be operated at high temperatures to reduce cell resistance, but endothermic reactions that occur before the gas reaches the electrochemical unit cell at the gas inlet or in the electrochemical unit cell at the gas inlet lower the operating temperature at the inlet of the cell stack. As a result, the internal resistance of the electrolytic reaction in the co-electrolysis cell stack increases, which increases the electrolysis voltage relative to the amount of gas produced and increases power consumption.

[0013] On the other hand, assuming that the overall effective area of ​​an electrochemical cell stack, including the heat exchanger, is constant, increasing the heat transfer area of ​​the heat exchanger for preheating the inlet fuel gas to a desired temperature and decreasing the heat transfer area of ​​the outlet heat exchanger may result in an increase in the exhaust gas temperature, potentially exceeding the allowable temperature of the constituent materials, such as the outlet connecting piping. Furthermore, increasing the heat transfer areas of both the inlet and outlet heat exchangers reduces the area of ​​the reaction section of the electrochemical cell stack, resulting in a decrease in the amount of power generation or produced gas. Therefore, to maximize the performance of an electrochemical cell stack with a given stack volume, it is necessary to appropriately set the heat transfer area of ​​the inlet heat exchanger for the fuel gas or feedstock gas and the heat transfer area of ​​the outlet heat exchanger for the exhaust gas or produced gas.

[0014] The present disclosure has been made in consideration of the above circumstances, and aims to provide an electrochemical cell stack that can preheat the supplied gas to a desired temperature even if there is a temperature drop due to an endothermic reaction that occurs before the gas reaches the electrochemical single cell, and that maximizes the amount of power generation or generated gas by keeping the maximum cell operating temperature and exhaust gas temperature at or below allowable values, an electrochemical cell cartridge and an electrochemical cell module that include the same, and methods for manufacturing the same.

[0015] Another object of the present disclosure is to provide a fuel cell stack that improves the temperature distribution in the cell stack and enables more efficient power generation.

[0016] Another object of the present disclosure is to provide a highly efficient co-electrolysis cell stack that can improve the temperature distribution in the cell stack and reduce the power consumption of the cell stack per amount of gas produced. [Means for solving the problem]

[0017] In order to solve the above problems, the electrochemical cell stack, the electrochemical cell cartridge and electrochemical cell module including the same, and the manufacturing methods thereof, fuel cell stack, and co-electrolysis cell stack of the present disclosure employ the following means.

[0018] The present disclosure provides an electrochemical cell stack comprising: a reaction section having an electrochemical cell formed by stacking a first electrode, a solid electrolyte membrane, and a second electrode in that order; a raw material gas inlet for supplying a raw material gas to the first electrode side of the reaction section; a product gas outlet for discharging a product gas generated in the reaction section; a raw material gas inlet heat exchanger containing a catalytic component that causes an endothermic reaction with the raw material gas, the raw material gas being on the raw material gas inlet side of the reaction section and performing heat exchange between the raw material gas and an oxidizing gas supplied to the second electrode side; and a product gas outlet heat exchanger on the product gas outlet side of the reaction section and performing heat exchange between the product gas and the oxidizing gas supplied to the second electrode side, the raw material gas inlet heat exchanger having a heat transfer area that is the same as or larger than the heat transfer area of ​​the product gas outlet heat exchanger.

[0019] The present disclosure provides an electrochemical cell cartridge comprising: the electrochemical cell stack described above; a raw material gas inlet side insulator having a hole through which the raw material gas supply port side end of the electrochemical cell stack is inserted, forming a gap between the raw material gas inlet heat exchanger of the electrochemical cell stack and the raw material gas inlet heat exchanger of the electrochemical cell stack, and a product gas outlet side insulator having a hole through which the product gas outlet port side end of the electrochemical cell stack is inserted, forming a gap between the raw material gas inlet side insulator and the product gas outlet heat exchanger of the electrochemical cell stack, wherein the region forming the gap with the hole in the raw material gas inlet side insulator is the heat transfer portion of the raw material gas inlet heat exchanger, and the region forming the gap with the hole in the product gas outlet side insulator is the heat transfer portion of the product gas outlet heat exchanger.

[0020] The present disclosure provides an electrochemical cell module including the electrochemical cell cartridge described above.

[0021] The present disclosure provides a reactor having an electrochemical unit cell formed by sequentially stacking a first electrode, a solid electrolyte membrane, and a second electrode; a raw material gas supply port for supplying a raw material gas to the first electrode side of the reactor; a raw material gas inlet heat exchanger containing a catalyst component that causes an endothermic reaction with the raw material gas and that exchanges heat between the raw material gas and an oxidizing gas supplied to the second electrode side on the raw material gas supply port side of the reaction unit; and a raw material gas outlet heat exchanger containing a catalyst component that causes an exothermic reaction with the raw material gas in the opposite direction to the supply side and that exchanges heat between the raw material gas and an oxidizing gas supplied to the second electrode side on the raw material gas outlet port side of the reaction unit, wherein the heat transfer area of ​​the raw material gas inlet heat exchanger is formed to be the same as or larger than the heat transfer area of ​​the product gas outlet heat exchanger.

[0022] the fuel gas inlet heat exchanger that contains a catalytic component that causes an endothermic reaction with the fuel gas and that exchanges heat between the fuel gas and an oxidizing gas supplied to the air electrode side, and an exhaust fuel gas outlet heat exchanger that is located closer to the fuel gas inlet than the power generation unit and that exchanges heat between the fuel gas and an oxidizing gas supplied to the air electrode side, and an exhaust fuel gas outlet heat exchanger that is located closer to the exhaust fuel gas outlet than the power generation unit and that exchanges heat between the exhaust fuel gas and the oxidizing gas supplied to the air electrode side, wherein the heat transfer area of ​​the fuel gas inlet heat exchanger is the same as or larger than the heat transfer area of ​​the exhaust fuel gas outlet heat exchanger.

[0023] The present disclosure provides a co-electrolysis cell stack comprising: a co-electrolysis unit having an electrolysis cell formed by stacking a hydrogen electrode, a solid electrolyte membrane, and an oxygen electrode in this order; a feed gas inlet for supplying a feed gas to the hydrogen electrode of the co-electrolysis unit; a product gas outlet for discharging a product gas generated in the co-electrolysis unit; a feed gas inlet heat exchanger containing a catalytic component that causes an endothermic reaction of the feed gas, the feed gas inlet heat exchanger being located closer to the feed gas inlet than the co-electrolysis unit and performing heat exchange between the feed gas and an oxidizing gas supplied to the oxygen electrode side; and a product gas outlet heat exchanger being located closer to the product gas outlet than the co-electrolysis unit and performing heat exchange between the product gas and the oxidizing gas supplied to the oxygen electrode side, wherein the heat transfer area of ​​the feed gas inlet heat exchanger is the same as or larger than the heat transfer area of ​​the product gas outlet heat exchanger. [Effects of the Invention]

[0024] According to the present disclosure, in an electrochemical cell stack in which the heat transfer area of ​​the raw material gas inlet heat exchanger is larger than or equal to the heat transfer area of ​​the product gas outlet heat exchanger, even if there is a temperature drop due to an endothermic reaction that occurs before the gas reaches the reaction section (electrochemical single cell), it is possible to preheat the gas supplied to the electrochemical single cell to the desired temperature and to keep the cell's maximum operating temperature and exhaust gas temperature below the allowable temperature.

[0025] When such an electrochemical cell stack is used as a fuel cell, more efficient power generation becomes possible.

[0026] When such an electrochemical cell stack is used for co-electrolysis hydrogen production, it is possible to reduce the power consumption of the cell stack per unit amount of produced gas (improving energy conversion efficiency). [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 illustrates an embodiment of an electrochemical cell stack according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged schematic cross-sectional view of the end of the power generation section of the electrochemical cell stack. [Figure 3]FIG. 1 illustrates an embodiment of an electrochemical cell module according to an embodiment of the present disclosure. [Figure 4] FIG. 1 shows one embodiment of a cross section of an electrochemical cell cartridge according to an embodiment of the present disclosure. [Figure 5] FIG. 10 is a diagram showing predicted temperature distribution in a fuel cell stack. [Figure 6] FIG. 10 is a diagram showing the IV characteristics of a fuel cell stack. [Figure 7] FIG. 1 is a diagram showing the simulation results of Examples 1 to 5 and Comparative Examples 1 and 2. [Figure 8] 1 is a graph showing the simulation results of Examples 1 to 5 and Comparative Examples 1 and 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, an embodiment of an electrochemical cell stack, an electrochemical cell cartridge, an electrochemical cell module, a method for manufacturing an electrochemical cell stack, a fuel cell stack, and a co-electrolysis cell stack according to the present disclosure will be described with reference to the drawings.

[0029] In the following, for the sake of convenience, the positional relationship of each component described using the expressions "upper" and "lower" with respect to the plane of the paper indicates the vertically upper side and the vertically lower side, respectively. Also, in this embodiment, for components that can obtain similar effects in the vertical direction and the horizontal direction, the vertical direction on the plane of the paper is not necessarily limited to the vertically upper and lower directions, but may correspond to, for example, a horizontal direction perpendicular to the vertical direction.

[0030] [First embodiment] First, the electrochemical cell stack according to this embodiment will be described with reference to FIG.

[0031] The electrochemical cell stack shown in Fig. 1 is a cylindrical cell stack using a substrate tube. The electrochemical cell stack has a reaction section in the center of its longitudinal direction, which has an electrochemical unit cell formed by stacking a first electrode, a solid electrolyte membrane, and a second electrode in that order.

[0032] When a substrate tube is not used, for example, the first electrode may be formed thick and used as the substrate tube, and the use of a substrate tube is not limited. Also, although the substrate tube in this embodiment is described as being cylindrical, the substrate tube may be tubular and the cross section is not necessarily limited to a circular one, and may be, for example, elliptical. A cell stack such as a flat tubular cylinder in which the peripheral side surface of a cylinder is crushed vertically may also be used.

[0033] The electrochemical cell stack 101 has a raw material gas supply port 11 and a product gas discharge port 12. The electrochemical cell stack 101 is equipped with a raw material gas inlet heat exchanger (raw material gas inlet side heat exchanger) 13 and a product gas outlet heat exchanger (product gas outlet side heat exchanger) 14, sandwiching the reaction section 10 from both sides in the longitudinal direction.

[0034] Alternatively, the electrochemical cell stack may be formed by stacking a plurality of flat-plate electrochemical single cells and separators, and a stack structure may be formed by stacking flat-plate heat exchange sections on the inlet and outlet sides of the reaction section of the electrochemical cell stack.

[0035] The raw material gas supply port 11 is an inlet for supplying the raw material gas to the first electrode 109 of the reaction section 10.

[0036] The raw material gas is intended for use in the reaction in the reaction section 10 and undergoes an endothermic reaction in the raw material gas inlet heat exchange section. For example, when the electrochemical cell stack 101 is applied as a fuel cell stack, the fuel gas may be a hydrocarbon fuel or ammonia gas. Examples of hydrocarbon fuels include methane gas and propane gas. Hydrocarbon fuels and ammonia gas are fuel gases that endotherm when reformed in the raw material gas inlet heat exchange section. When the electrochemical cell stack 101 is applied as a co-electrolysis cell stack, the raw material gas may be a mixed gas containing hydrogen in addition to water vapor and carbon dioxide gas. Such a mixed gas endotherm occurs in the raw material gas inlet heat exchange section.

[0037] When methane gas is supplied as fuel, the endothermic reaction shown in equation (1) occurs due to the reforming reaction. CH4+H2O=3H2+CO-206.1kJ / mol...(1)

[0038] Furthermore, when ammonia gas is supplied as the fuel gas, an endothermic reaction of the following formula (2) occurs. 2NH3=N2+3H2-92.2kJ / mol···(2)

[0039] This endothermic reaction occurs significantly before the fuel gas reaches the electrochemical unit cell at the inlet side of the cell stack or in the electrochemical unit cell at the inlet side, causing the temperature of the fuel gas to drop. When the fuel gas temperature is low, the internal resistance of the electrochemical unit cell increases, reducing the voltage that can be extracted externally. This reduces the power (current x voltage) that can be extracted from the electrochemical cell stack.

[0040] Such a problem may also arise in a co-electrolytic cell stack when a gas containing hydrogen to prevent oxidation of the metal material is supplied as a raw material gas in addition to water vapor and carbon dioxide.

[0041] When a gas containing hydrogen in addition to water vapor and carbon dioxide is supplied as a feed gas to the co-electrolysis cell stack, an endothermic reaction called the reverse water-gas shift reaction, as shown in equation (3) below, occurs in the high-temperature part at the gas inlet of the co-electrolysis cell stack. CO2+H2=CO+H2O-41.2kJ / mol···(3)

[0042] The gas supplied from the raw material gas supply port 11 may contain components for other purposes in addition to components (raw material gas) intended to be used in the reaction in the reaction section 10. The components for other purposes may be components intended to prevent oxidation of catalytic components (nickel, etc.) contained in the first electrode, the raw material gas inlet heat exchange section, etc. The term "raw material gas" described below primarily refers to a gas containing components intended to be used in the reaction in the reaction section 10, but does not exclude the inclusion of components for other purposes.

[0043] The product gas outlet 12 is an outlet for discharging the gas generated in the reaction section (product gas) to the outside of the electrochemical cell stack 101. The gas discharged from the product gas outlet 12 may contain, in addition to the gas generated in the reaction section 10, unreacted raw material gas that was not used in the reaction section. Hereinafter, the product gas containing unreacted raw material gas will also be referred to as "exhaust raw material gas."

[0044] The raw gas inlet heat exchanger 13 is located on the raw gas supply port 11 side of the reaction section 10. The raw gas inlet heat exchanger 13 is a region where the raw gas supplied from the raw gas supply port 11 into the electrochemical cell stack 101 exchanges heat with the oxidizing gas flowing outside the electrochemical cell stack 101 before entering the reaction section 10. The raw gas inlet heat exchanger 13 may include a lead portion (a lead film 115 described later) electrically connected to the reaction section 10. Specifically, the raw gas inlet heat exchanger 13 is a region from the end (outer end) of the electrochemical unit cell 105 on the raw gas supply port 11 side formed in the cell stack 101 to the upper tube plate 225a described later. Note that the raw gas inlet heat exchanger 13 does not necessarily include the area from the upper tube plate 225a to the top end of the cell stack 101. Furthermore, the raw gas inlet heat exchanger 13 does not necessarily have to be molded integrally with the reaction section 10, but may be a structure or a heat exchanger having a heat exchange function between the oxidizing gas and the raw gas.

[0045] Of the raw material gas inlet heat exchanger 13, the oxidizing gas discharge gap 235b (described later) that exchanges heat between the raw material gas and the oxidizing gas may be used as the heat transfer section (L1). The oxidizing gas discharge gap 235b is a passage for the oxidizing gas formed between the outer surface of the cell stack 101 and the upper heat insulator 227a (described later), and is a region where heat exchange occurs between the raw material gas and the exhaust oxidizing gas. In other words, the raw material gas inlet heat exchanger 13 is a region that combines the region from the end (outer end) of the electrochemical unit cell 105 on the raw material gas supply port 11 side formed in the cell stack 101 to the oxidizing gas discharge gap 235b, the heat transfer section (L1), and the portion that penetrates the oxidizing gas discharge header 223.

[0046] The product gas outlet heat exchanger 14 is located on the product gas outlet 12 side of the reaction section 10. The product gas outlet heat exchanger 14 is a region where heat is exchanged between the product gas (exhaust feed gas) generated in the reaction section 10 and the oxidizing gas flowing outside the electrochemical cell stack 101 to be supplied to the second electrode 113. The product gas outlet heat exchanger 14 may include a lead portion (a lead film 115 described below) electrically connected to the reaction section 10. Specifically, the product gas outlet heat exchanger 14 is a region from the end (outer end) of the electrochemical unit cell 105 on the product gas outlet 12 side formed in the cell stack 101 to the lower tube plate 225b described below. Note that the product gas outlet heat exchanger 14 does not include the area from the lower tube plate 225b to the lower end of the cell stack 101. Furthermore, the product gas outlet heat exchanger 14 does not necessarily have to be molded integrally with the reaction section 10, but may be a structure or heat exchanger having a heat exchange function between the oxidizing gas and the exhaust feed gas.

[0047] Of the produced gas outlet heat exchanger 14, the oxidizing gas supply gap 235a, which exchanges heat between the produced gas and the oxidizing gas, may be used as the heat transfer section (L3). The oxidizing gas supply gap 235a is a passage for the oxidizing gas formed between the outer surface of the cell stack 101 and a lower insulator 227b (described later), and is the region where heat exchange between the produced gas and the oxidizing gas occurs. In other words, the lower heat exchanger 14 is the combined region of the region from the end (outer end) of the electrochemical unit cell 105 on the produced gas outlet 12 side formed in the cell stack 101 to the oxidizing gas supply gap 235a, the heat transfer section (L3), and the portion penetrating the oxidizing gas supply header 221.

[0048] The heat transfer area (S1) of the heat transfer section (L1) of the raw material gas inlet heat exchange section 13 is the same as or larger than the heat transfer area (S3) of the heat transfer section (L3) of the produced gas outlet heat exchange section 14. The ratio (S1 / S3) of the heat transfer area (S1) of the raw material gas inlet heat exchange section 13 to the heat transfer area (S3) of the produced gas outlet heat exchange section 14 is preferably 1 or more and 4 or less.

[0049] Here, the effective area (S) of the electrochemical cell stack 101 is defined as the sum of the heat transfer area (S1) of the raw material gas inlet heat exchange section 13, the reaction area of ​​the reaction section 10 (reaction area S2), and the heat transfer area (S3) of the product gas outlet heat exchange section 14.

[0050] When the diameter of the substrate tubes of a cylindrical cell stack is uniform, the heat transfer area can be considered as the length. The effective length (L) of the electrochemical cell stack 101 is the sum of the heat transfer length (L1) of the raw material gas inlet heat exchanger 13, the length (L2) of the reaction section 10, and the heat transfer length (L3) of the product gas outlet heat exchanger 14.

[0051] The heat transfer section length (L1) of the raw material gas inlet heat exchange section 13 is the same as or longer than the heat transfer section length (L3) of the produced gas outlet heat exchange section 14. The ratio (L1 / L3) of the heat transfer section length (L1) of the raw material gas inlet heat exchange section 13 to the heat transfer section length (L3) of the produced gas outlet heat exchange section 14 may be 1 or more and 4 or less.

[0052] A plurality of electrochemical cell stacks 101 are assembled using a source gas header or the like to form an electrochemical cell cartridge. An electrochemical cell module is composed of one or more cartridges, a heat insulator, a storage container, etc. The electrochemical cell cartridge and electrochemical cell module will be described in detail in the second embodiment.

[0053] Second Embodiment In this embodiment, a case where an electrochemical cell stack is used as a fuel cell will be described. The basic configuration is the same as in the first embodiment. The first electrode is the "fuel electrode," the second electrode is the "air electrode," the electrochemical unit cell is the "fuel cell unit," the reaction section is the "power generation section," the raw material gas is the "fuel gas," the electrochemical cell stack is the "fuel cell stack," the electrochemical cell cartridge is the "fuel cell cartridge," and the electrochemical cell module is the "fuel cell module." The same reference numerals as in the first embodiment are used for corresponding components.

[0054] (Fuel cell stack) FIG. 2 is an enlarged schematic cross-sectional view of the end of the power generation section of the fuel cell stack. The fuel cell stack (hereinafter simply referred to as cell stack) comprises a power generating section 10 having a single fuel cell 105 in the longitudinal center, where the single fuel cell 105 is made up of a fuel electrode 109, a solid electrolyte membrane 111, and an air electrode 113 stacked in this order.

[0055] The cell stack 101 has a fuel gas supply port 11 and an exhaust fuel gas discharge port 12. The cell stack is provided with a fuel gas inlet heat exchanger 13 and an exhaust fuel gas outlet heat exchanger 14, which sandwich the power generation section 10 from both sides in the longitudinal direction. The heat transfer area (or length) of the fuel gas inlet heat exchanger 13 and the exhaust fuel gas outlet heat exchanger 14 is the same as in the first embodiment.

[0056] As an example, the cell stack 101 has a cylindrical substrate tube 103, and a plurality of fuel cell units 105 are formed on the outer peripheral surface of the substrate tube 103. In the power generation section 10, adjacent fuel cell units 105 are electrically connected by interconnectors.

[0057] The cell stack also includes a lead film 115 electrically connected via an interconnector 107 to the air electrode 113 of the fuel cell unit 105 formed at one end of the fuel cell unit 105 at the extreme end in the axial direction of the base tube 103 among the plurality of fuel cell unit 105 formed on the outer peripheral surface of the base tube 103, and a lead film 115 electrically connected to the fuel electrode 109 of the fuel cell unit 105 formed at the other extreme end. The outer end of the oxygen electrode 113 of the fuel cell unit 105 located at the extreme end becomes the end of the power generation section 10.

[0058] The base tube 103 is made of a porous material, and its main component is, for example, CaO-stabilized ZrO2 (CSZ), a mixture of CSZ and nickel oxide (NiO) (CSZ+NiO), Y2O3-stabilized ZrO2 (YSZ), or MgAl2O4. The base tube 103 supports the fuel cell unit cells 105, the interconnector 107, and the lead film 115, and also diffuses the fuel gas supplied to the inner peripheral surface of the base tube 103 through the pores of the base tube 103 to the fuel electrode 109 formed on the outer peripheral surface of the base tube 103.

[0059] The diameters (outer diameter and inner diameter) of the substrate tube 103 may be uniform in the longitudinal direction. The outer diameter of the substrate tube 103 is, for example, 10 to 50 mm. The total length of the substrate tube 103 is, for example, 500 to 3000 mm.

[0060] The anode 109 is made of a composite oxide of Ni and a zirconia-based electrolyte material, and for example, Ni / YSZ is used. The thickness of the anode 109 is 50 μm to 250 μm, and the anode 109 may be formed by screen-printing a slurry. In this case, the nickel contained in the anode 109 has a catalytic effect on the fuel gas. This catalytic effect causes the fuel gas supplied via the substrate tube 103, for example, a mixed gas of methane (CH4) and water vapor, to react and reform into hydrogen (H2) and carbon monoxide (CO). The anode 109 also reacts the hydrogen (H2) and carbon monoxide (CO) obtained by reforming with oxygen ions (O2) supplied via the solid electrolyte membrane 111. 2- ) are electrochemically reacted near the interface with the solid electrolyte membrane 111 to generate water (H2O) and carbon dioxide (CO2). At this time, the single fuel cell 105 generates electricity using electrons released from the oxygen ions.

[0061] The fuel gas supplied to the anode 109 of the solid oxide electrochemical unit cell may be a gas that causes an endothermic reaction in the raw gas inlet heat exchanger 13. Examples of fuel gases that cause an endothermic reaction include hydrocarbon fuels such as methane gas and propane gas, and ammonia gas.

[0062] The solid electrolyte membrane 111 is mainly made of YSZ, which has gas-tightness that makes it difficult for gas to pass through and high oxygen ion conductivity at high temperatures. The solid electrolyte membrane 111 is made of YSZ, which has high oxygen ion conductivity at high temperatures and is highly resistant to oxygen ions (O 2- ) to the fuel electrode. Solid electrolyte membrane 111 located on the surface of fuel electrode 109 has a thickness of 10 μm to 100 μm, and may be formed by screen printing a slurry.

[0063] The air electrode 113 is made of, for example, LaSrMnO3-based oxide or LaCoO3-based oxide, and a slurry is applied to the air electrode 113 by screen printing or by using a dispenser. The air electrode 113 dissociates oxygen in an oxidizing gas such as air supplied near the interface with the solid electrolyte membrane 111, and combines with electrons supplied from the outside to produce oxygen ions (O 2- ) is generated.

[0064] The air electrode 113 can also have a two-layer structure. In this case, the air electrode layer (air electrode intermediate layer) on the solid electrolyte membrane 111 side exhibits high ionic conductivity and is made of a material with excellent catalytic activity. The air electrode layer (air electrode conductive layer) on the air electrode intermediate layer may be made of a perovskite-type oxide such as Sm-doped ceria or Sr- and Ca-doped LaMnO3. This can further improve power generation performance.

[0065] An oxidizing gas is a gas containing approximately 15% to 30% oxygen, and air is a typical example, but other gases such as a mixture of combustion exhaust gas and air, or a mixture of oxygen and air can also be used.

[0066] The interconnector 107 is made of M such as SrTiO3. 1-x L xThe interconnector 107 is made of a conductive perovskite oxide represented by TiO3 (M is an alkaline earth metal element, L is a lanthanoid element), and the slurry is screen-printed. The interconnector 107 is a dense film that prevents the fuel gas and oxidizing gas from mixing. The interconnector 107 also has stable durability and electrical conductivity in both oxidizing and reducing atmospheres. This interconnector 107 electrically connects the air electrode 113 of one fuel cell unit 105 to the fuel electrode 109 of the other fuel cell unit 105 in adjacent fuel cell unit cells 105, and connects the adjacent fuel cell unit cells 105 in series.

[0067] The lead film 115 is required to have electronic conductivity and a thermal expansion coefficient close to that of the other materials constituting the cell stack 101. Therefore, a composite material of nickel and zirconia-based electrolyte material such as Ni / YSZ, or a M material such as SrTiO3-based 1-x L x It is made of TiO3 (M is an alkaline earth metal element, and L is a lanthanoid element). This lead film 115 guides the DC power generated by the plurality of fuel cell units 105 connected in series by the interconnectors 107 to the vicinity of the end of the cell stack 101.

[0068] The lead film 115 connected to the fuel cell unit cell 105 located closest to the fuel gas supply port 11 extends over the fuel gas inlet heat exchanger 13. The lead film 115 connected to the fuel cell unit cell 105 located closest to the exhaust fuel gas discharge port 12 extends over the exhaust fuel gas outlet heat exchanger 14. The fuel gas inlet heat exchanger 13 (or the exhaust fuel gas outlet heat exchanger 14) has a function to allow current to flow. The nickel contained in the lead film 115 also acts as a catalyst to cause the fuel gas to undergo a reforming reaction (endothermic reaction).

[0069] Next, a method for manufacturing the cell stack 101 will be described.

[0070] The substrate tube 103 is formed by, for example, an extrusion molding method. The outer peripheral surface of the base tube 103 is divided into a fuel gas inlet heat exchange section, a power generation section, and an exhaust fuel gas outlet heat exchange section along the axial direction (longitudinal direction). The power generation section is located in the central portion of the base tube 103 in the axial direction, the fuel gas inlet heat exchange section is located on the fuel gas supply port 11 side of the power generation section, and the exhaust fuel gas outlet heat exchange section is located on the exhaust fuel gas discharge port 12 side of the power generation section.

[0071] The fuel gas inlet heat exchange section and the exhaust fuel gas outlet heat exchange section are set so that the heat transfer section area (S1) of the fuel gas inlet heat exchange section is the same as or larger than the heat transfer section area (S3) of the exhaust fuel gas outlet heat exchange section. The ratio (S1 / S3) of the heat transfer section area (S1) of the fuel gas inlet heat exchange section to the heat transfer section area (S3) of the exhaust fuel gas outlet heat exchange section may be 1 or more and 4 or less.

[0072] If the diameter of the substrate tube 103 is uniform in the longitudinal direction, the "heat transfer section area" may be converted to the "heat transfer section length" to set the fuel gas inlet heat exchange section, the power generation section, and the exhaust fuel gas outlet heat exchange section.

[0073] A slurry for the anode is applied to the outer peripheral surface of the substrate tube 103 in the power generation region. A slurry for the lead film is applied next to the slurry for the anode applied at the very end. The slurry for the lead film may straddle the fuel gas inlet heat exchanger (or the exhaust fuel gas outlet heat exchanger) and the power generation region.

[0074] After the slurry for the fuel electrode is applied, the slurry for the solid electrolyte membrane and the slurry for the interconnector are applied in this order.

[0075] The base tube 103 on which the fuel electrode 109, the solid electrolyte membrane 111, and the interconnector 107 slurry film are formed is co-sintered in the atmosphere at a sintering temperature of, for example, 1350°C to 1450°C.

[0076] Next, the slurry for the air electrode is applied onto the co-sintered substrate tube 103. The outermost end of the slurry for the air electrode that is applied to the outermost end becomes the end of the power generation region.

[0077] The base tube 103 on which the slurry film of the air electrode 113 has been formed is sintered in the atmosphere. The sintering temperature is set to, for example, 1100° C. to 1250° C. The sintering temperature here is set to a lower temperature than the co-sintering temperature after the base tube 103 to the interconnector 107 are formed.

[0078] This results in a cell stack 101 in which the heat transfer area (S1) of the fuel gas inlet heat exchanger 13 is the same as or larger than the heat transfer area (S3) of the exhaust fuel gas outlet heat exchanger 14.

[0079] Next, a fuel cell module and a fuel cell cartridge according to this embodiment will be described with reference to Figures 3 and 4. Here, Figure 3 shows one embodiment of a solid oxide fuel cell (SOFC) module according to this embodiment. Also, Figure 4 shows a cross-sectional view of one embodiment of a solid oxide fuel cell (SOFC) cartridge according to this embodiment.

[0080] (Fuel cell module) As shown in FIG. 3, a fuel cell module (hereinafter simply referred to as module) 201 includes, for example, a plurality of fuel cell cartridges (hereinafter simply referred to as cartridges) 203 and a module container 205 that houses the plurality of cartridges 203. While FIG. 3 illustrates a cylindrical cell stack 101, this is not necessarily the case and a flat cell stack may also be used. The module 201 also includes a fuel gas supply pipe 207, a plurality of fuel gas supply branch pipes 207a, a fuel gas discharge pipe (produced gas discharge pipe) 209, and a plurality of fuel gas discharge branch pipes (produced gas discharge pipes) 209a. The module 201 also includes an oxidizing gas supply pipe (not shown), an oxidizing gas supply branch pipe (not shown), an oxidizing gas discharge pipe (not shown), and a plurality of oxidizing gas discharge branch pipes (not shown).

[0081] The fuel gas supply pipe 207 is provided inside the module container 205 and is connected to a fuel gas supply unit that supplies fuel gas with a predetermined gas composition and a predetermined flow rate corresponding to the power generation amount of the module 201, and is also connected to multiple fuel gas supply branch pipes 207a. This fuel gas supply pipe 207 branches and guides the fuel gas supplied from the fuel gas supply unit at a predetermined flow rate to the multiple fuel gas supply branch pipes 207a. Furthermore, the fuel gas supply branch pipe 207a is connected to the fuel gas supply pipe 207 and is also connected to the multiple cartridges 203. This fuel gas supply branch pipe 207a guides the fuel gas supplied from the fuel gas supply pipe 207 to the multiple cartridges 203 at a substantially uniform flow rate, thereby substantially uniforming the power generation performance of the multiple cartridges 203.

[0082] The fuel gas discharge branch pipe 209a is connected to the plurality of cartridges 203 and is also connected to the fuel gas discharge pipe 209. This fuel gas discharge branch pipe 209a guides the exhaust fuel gas (produced gas containing unused fuel gas) discharged from the cartridges 203 to the fuel gas discharge pipe 209. The fuel gas discharge pipe 209 is also connected to the plurality of fuel gas discharge branch pipes 209a and is partially disposed outside the module container 205. This fuel gas discharge pipe 209 guides the exhaust fuel gas discharged at a substantially uniform flow rate from the fuel gas discharge branch pipe 209a to the outside of the module container 205.

[0083] The module container 205 is operated with an internal pressure of atmospheric pressure to several MPa and a surface temperature of atmospheric temperature to approximately 300° C., and is preferably made of carbon steel, for example, from the viewpoint of cost reduction.

[0084] Here, in this embodiment, a configuration in which multiple cartridges 203 are grouped together and stored in a modular container 205 is described, but this is not limited to this, and for example, the cartridges 203 can also be stored in a modular container 205 without being grouped together.

[0085] (Fuel cell cartridge) As shown in Figure 4, the cartridge 203 includes a plurality of cell stacks 101, a power generation chamber 215, a fuel gas supply header 217, a fuel gas discharge header (product gas discharge header) 219, an oxidizing gas (air) supply header 221, and an oxidizing gas discharge header 223. The cartridge 203 also includes an upper tube plate 225a, a lower tube plate 225b, an upper insulator 227a, and a lower insulator 227b. In this embodiment, the cartridge 203 has a structure in which the fuel gas supply header 217, the fuel gas discharge header 219, the oxidizing gas supply header 221, and the oxidizing gas discharge header 223 are arranged as shown in Figure 4, so that the fuel gas and the oxidizing gas flow in opposing directions inside and outside the cell stack 101. However, this is not necessarily required. For example, the fuel gas and the oxidizing gas may flow in parallel inside and outside the cell stack 101, or the oxidizing gas may flow in a direction perpendicular to the longitudinal direction of the cell stack 101.

[0086] 4, the fuel gas inlet heat exchanger 13 of the cell stack 101 extends from the lower surface of the upper tube plate 225a to the upper end (outer end) of the uppermost fuel cell unit 105 among the plurality of fuel cell unit cells 105. In Fig. 4, the exhaust fuel gas outlet heat exchanger 14 of the cell stack 101 extends from the lower end (outer end) of the lowermost fuel cell unit 105 among the plurality of fuel cell unit cells 105 to the upper surface of the lower tube plate 225b.

[0087] The power generation chamber 215 is a region formed between the upper insulator 227a and the lower insulator 227b. This power generation chamber 215 is a region in which the single fuel cell 105 of the cell stack 101 is arranged, and is a region in which power is generated by electrochemically reacting fuel gas with oxidizing gas. The temperature near the center of the cell stack 101 in the longitudinal direction of the power generation chamber 215 may be monitored by a temperature measurement unit (such as a temperature sensor or thermocouple), and during steady-state operation of the fuel cell module 201, a high-temperature atmosphere of approximately 700°C to 1000°C is created.

[0088] The fuel gas supply header 217 is an area surrounded by the upper casing 229a and upper tube plate 225a of the cartridge 203, and is connected to the fuel gas supply branch pipe 207a via fuel gas supply holes 231a provided in the upper part of the upper casing 229a. The multiple cell stacks 101 are joined to the upper tube plate 225a by upper seal members 237a, and the fuel gas supply header 217 guides the fuel gas supplied from the fuel gas supply branch pipe 207a via the fuel gas supply holes 231a into the base tubes 103 of the multiple cell stacks 101 at a substantially uniform flow rate, thereby substantially uniforming the power generation performance of the multiple cell stacks 101.

[0089] The fuel gas discharge header 219 is an area surrounded by the lower casing 229b and lower tube plate 225b of the cartridge 203, and is connected to a fuel gas discharge branch pipe 209a (not shown) via fuel gas discharge holes (produced gas discharge holes) 231b provided in the lower casing 229b. The multiple cell stacks 101 are joined to the lower tube plate 225b by a lower seal member 237b, and the fuel gas discharge header 219 collects exhaust fuel gas that passes through the insides of the base tubes 103 of the multiple cell stacks 101 and is supplied to the fuel gas discharge header 219, and leads it to the fuel gas discharge branch pipe 209a via the fuel gas discharge holes 231b.

[0090] Oxidizing gas with a predetermined gas composition and flow rate corresponding to the power generation amount of module 201 is branched into oxidizing gas supply branch pipes and supplied to multiple cartridges 203. Oxidizing gas supply header 221 is an area surrounded by lower casing 229b, lower tube sheet 225b, and lower insulator 227b of cartridge 203, and is connected to an oxidizing gas supply branch pipe (not shown) via oxidizing gas supply holes 233a provided on the side surface of lower casing 229b. This oxidizing gas supply header 221 guides oxidizing gas at a predetermined flow rate, supplied from the oxidizing gas supply branch pipe (not shown) via oxidizing gas supply holes 233a, to power generating chamber 215 via oxidizing gas supply gap 235a (described below).

[0091] The oxidizing gas discharge header 223 is an area surrounded by the upper casing 229a, upper tube plate 225a, and upper heat insulator 227a of the cartridge 203, and is connected to an oxidizing gas discharge branch pipe (not shown) through oxidizing gas discharge holes 233b provided on the side surface of the upper casing 229a. The oxidizing gas discharge header 223 guides the exhaust oxidizing gas supplied to the oxidizing gas discharge header 223 from the power generating chamber 215 through an oxidizing gas discharge gap 235b (described later) to the oxidizing gas discharge branch pipe (not shown) through the oxidizing gas discharge holes 233b.

[0092] The upper tube plate 225a is fixed to the side plate of the upper casing 229a between the top plate of the upper casing 229a and the upper insulator 227a so that the upper tube plate 225a, the top plate of the upper casing 229a, and the upper insulator 227a are approximately parallel to each other. The upper tube plate 225a has a number of holes corresponding to the number of cell stacks 101 provided in the cartridge 203, and the cell stacks 101 are inserted into the holes. The upper tube plate 225a airtightly supports one end of the multiple cell stacks 101 via either or both of an upper seal member 237a and an adhesive member, and also isolates the fuel gas supply header 217 from the oxidizing gas discharge header 223.

[0093] The upper heat insulator 227a is disposed at the lower end of the upper casing 229a so that the upper heat insulator 227a, the top plate of the upper casing 229a, and the upper tube plate 225a are substantially parallel to each other, and is fixed to the side plate of the upper casing 229a. The upper heat insulator 227a has a plurality of holes formed therein corresponding to the number of cell stacks 101 provided in the cartridge 203. The diameters of the holes are set larger than the outer diameters of the cell stacks 101. The upper heat insulator 227a has an oxidizing gas discharge gap 235b formed between the inner surface of the hole and the outer surface of the cell stack 101 inserted into the upper heat insulator 227a. The oxidizing gas discharge gap 235b is a region (heat transfer section L1) where heat exchange between the fuel gas and the oxidizing gas takes place.

[0094] The upper insulator 227a separates the power generating chamber 215 from the oxidizing gas discharge header 223, and prevents the atmosphere around the upper tube sheet 225a from becoming hot, thereby reducing its strength and increasing corrosion caused by the oxidizing agent contained in the oxidizing gas. Furthermore, a metal material with high temperature resistance, such as a nickel-based alloy, may be used to prevent thermal deformation of the upper tube sheet 225a and other components due to temperature differences when the upper tube sheet 225a and other components are exposed to high temperatures within the power generating chamber 215. The upper insulator 227a also guides the exhaust oxidizing gas, which has passed through the power generating chamber 215 and been exposed to high temperatures, through the oxidizing gas discharge gap 235b and into the oxidizing gas discharge header 223.

[0095] Heat exchange between the fuel gas and the oxidizing gas in the fuel gas inlet heat exchanger 13 occurs when the oxidizing gas passes through the oxidizing gas discharge gap 235b (heat transfer section L1 of the fuel gas inlet heat exchanger). Note that heat exchange in the fuel gas inlet heat exchanger 13 in areas other than the heat transfer section L1 (the area from the end (outer end) of the fuel cell unit cell 105 on the fuel gas supply port 11 side formed in the cell stack 101 to the oxidizing gas discharge gap 235b and the portion penetrating the oxidizing gas discharge header 223) is slight and can be ignored.

[0096] The thickness of the upper heat insulator 227a may be changed as appropriate, and the amount of heat exchanged can be increased by increasing the thickness of the upper heat insulator 227a. The length of the fuel gas inlet heat exchange section that penetrates the oxidizing gas discharge header 223 may be constant regardless of the heat transfer section area (length) of the fuel gas inlet heat exchange section 13.

[0097] According to this embodiment, the structure of the cartridge 203 described above allows the fuel gas and the exhaust oxidizing gas to flow in opposite directions inside and outside the cell stack 101. As a result, the exhaust oxidizing gas exchanges heat with the fuel gas that passes through the inside of the base tube 103 and is supplied to the power-generating chamber 215, and is cooled to a temperature at which the upper tube plate 225a, made of a metal material, and other components will not undergo deformation, such as buckling, before being supplied to the oxidizing gas discharge header 223. The fuel gas is also heated by heat exchange with the exhaust oxidizing gas discharged from the power-generating chamber 215 in the heat transfer section of the fuel gas inlet heat exchanger 13, and is then supplied to the power-generating chamber 215. As a result, fuel gas that has been preheated to a temperature suitable for power generation can be supplied to the power-generating chamber 215 without using a heater or the like.

[0098] The lower tube plate 225b is fixed to the side plate of the lower casing 229b between the bottom plate of the lower casing 229b and the lower insulator 227b so that the lower tube plate 225b, the bottom plate of the lower casing 229b, and the lower insulator 227b are approximately parallel to each other. The lower tube plate 225b has a number of holes corresponding to the number of cell stacks 101 provided in the cartridge 203, and the cell stacks 101 are inserted into the holes. The lower tube plate 225b airtightly supports the other ends of the multiple cell stacks 101 via either or both of a lower seal member 237b and an adhesive member, and also isolates the fuel gas discharge header 219 from the oxidizing gas supply header 221.

[0099] The lower heat insulator 227b is disposed at the upper end of the lower casing 229b so that the lower heat insulator 227b, the bottom plate of the lower casing 229b, and the lower tube plate 225b are substantially parallel to each other, and is fixed to the side plate of the lower casing 229b. The lower heat insulator 227b has a plurality of holes formed therein corresponding to the number of cell stacks 101 provided in the cartridge 203. The diameters of the holes are set larger than the outer diameters of the cell stacks 101. The lower heat insulator 227b has an oxidizing gas supply gap 235a (heat transfer section L3) formed between the inner surface of the hole and the outer surface of the cell stack 101 inserted through the lower heat insulator 227b. The oxidizing gas supply gap 235a is a region (heat transfer section L3) where heat exchange between the exhaust fuel gas and the oxidizing gas takes place.

[0100] The lower heat insulator 227b separates the power generating chamber 215 from the oxidizing gas supply header 221, and prevents the atmosphere surrounding the lower tube sheet 225b from becoming hot, thereby reducing its strength and increasing corrosion caused by the oxidizing agent contained in the oxidizing gas. Furthermore, a metal material with high temperature resistance, such as a Ni-based alloy, may be used to prevent thermal deformation of the upper tube sheet 225a and other components due to temperature differences when the upper tube sheet 225a and other components are exposed to high temperatures within the power generating chamber 215. The lower heat insulator 227b also guides the oxidizing gas supplied to the oxidizing gas supply header 221 to the power generating chamber 215 by passing it through the oxidizing gas supply gap 235a.

[0101] Heat exchange between the produced hydrogen and the oxidizing gas in the exhaust fuel gas outlet heat exchanger 14 occurs when the oxidizing gas passes through the oxidizing gas supply gap 235a (heat transfer section L3 of the exhaust fuel gas outlet heat exchanger). Note that heat exchange in areas of the exhaust fuel gas outlet heat exchanger 14 other than the heat transfer section L3 (the area from the end (outer end) of the fuel cell unit cell 105 on the exhaust fuel gas discharge port 12 side formed in the cell stack 101 to the oxidizing gas supply gap 235a and the portion penetrating the oxidizing gas supply header 221) is slight and can be ignored.

[0102] The thickness of the lower heat insulator 227b may be changed as appropriate, and the amount of heat exchanged can be increased by increasing the thickness of the lower heat insulator 227b. The length of the exhaust fuel gas outlet heat exchange section 14 that penetrates the oxidizing gas supply header 221 may be constant regardless of the heat transfer section area (length) of the exhaust fuel gas outlet heat exchange section 14.

[0103] According to this embodiment, the structure of the cartridge 203 described above allows the exhaust fuel gas and the oxidizing gas to flow in opposite directions inside and outside the cell stack 101. As a result, the exhaust fuel gas that passes through the inside of the base tube 103 and the power generating chamber 215 exchanges heat with the oxidizing gas supplied to the power generating chamber 215 in the exhaust fuel gas outlet heat exchanger 14, and is cooled to a temperature at which the lower tube plate 225b, made of a metal material, and the like will not undergo deformation such as buckling, and is supplied to the fuel gas discharge header 219. The oxidizing gas is also heated by heat exchange with the exhaust fuel gas and is supplied to the power generating chamber 215. As a result, the oxidizing gas heated to a temperature required for power generation can be supplied to the power generating chamber 215 without using a heater or the like.

[0104] The DC power generated in the power generation chamber 215 is conducted to the vicinity of the end of the cell stack 101 by lead films 115 made of Ni / YSZ or the like provided on the plurality of fuel cell unit cells 105, and then collected by a current collecting member (not shown) of the cartridge 203 via a current collecting plate (not shown) and taken out to the outside of each cartridge 203. The DC power conducted out to the outside of the cartridges 203 by the current collecting member is conducted out to the outside of the module 201 by interconnecting the generated power of each cartridge 203 in a predetermined number of series and parallel connections, and is converted into predetermined AC power by a power conversion device (inverter, etc.) such as a power conditioner (not shown) and supplied to the power supply destination (for example, load equipment or a power system).

[0105] 2, 3 and 4 have been described as embodiments of a fuel cell, but they are not limited to fuel cells and can also be used as an electrochemical cell stack, an electrochemical cell cartridge, or an electrochemical cell module.

[0106] Next, the basis for setting the heat transfer area (length) of the fuel gas inlet heat exchanger and the heat transfer area (length) of the exhaust fuel gas outlet heat exchanger will be described.

[0107] (Cell stack temperature distribution under SOFC operating conditions) Figure 5 shows a comparison between the predicted and measured temperature distributions of the cell stack under SOFC operating conditions. The solid line is the measured value (Example), and the dashed line is the predicted temperature distribution (Comparative Example). In the measured value, the heat transfer section length (L1) of the fuel gas inlet heat exchanger is longer than the heat transfer section length (L3) of the fuel gas outlet heat exchanger, while in the Comparative Example, the heat transfer section length (L1) of the fuel gas inlet heat exchanger is shorter than the heat transfer section length (L3) of the fuel gas outlet heat exchanger. In the figure, the horizontal axis is fuel gas temperature (°C), and the vertical axis is the height from the bottom end of the lower heat transfer section of the cell stack (base tube). In the Example, the length of the fuel gas inlet heat exchanger is L1, the length of the power generation section is L2, and the length of the fuel gas outlet heat exchanger is L3; in the Comparative Example, the length of the fuel gas inlet heat exchanger is L 1’ , the length of the power generating section is L 2’ , the length of the fuel gas outlet heat exchange section is L 3’ The fuel gas flows through the inside of the base tube at the top (L1, L 1’ ) to the bottom (L3,L 3’ The oxidizing gas flows along the outside of the substrate tube and reaches the bottom end (L3, L 3’ ) toward the upper end (L1). The reaction length L2 of the power generation section of the example and the comparative example is the same. The length (L1) of the heat transfer section of the fuel gas inlet heat exchange section in the cell stack of the example is twice the length (L3) of the heat transfer section of the exhaust fuel gas outlet heat exchange section. double The length of the heat transfer section of the fuel gas inlet heat exchanger in the cell stack of the comparative example (L 1’ ) is the length of the heat transfer section of the exhaust fuel gas outlet heat exchanger (L 3’ 1 / 2 of double is.

[0108] The fuel gas is transferred to the heat transfer section (L1, L2) of the fuel gas inlet heat exchanger by heat exchange with the oxidizing gas. 1’ The heat transfer section (L3, L 3’As can be seen from Figure 5, by increasing the length (L1) of the heat transfer section at the fuel gas inlet heat exchanger, the amount of heat exchanged with the oxidizing gas increases, raising the temperature of the fuel gas supplied to the power generation section after the endothermic reaction. The temperatures of the fuel gas and cell stack are highest near the center in the longitudinal direction. In SOFC operation, the current density is set lower than in SOEC operation, so the fuel gas flow rate and oxidizing gas flow rate are also lower. Therefore, as shown in Figure 5, even if the heat transfer section length (L3) at the exhaust fuel gas outlet heat exchanger is somewhat shorter than the heat transfer section length (L1) of the fuel gas inlet heat exchanger, the temperature of the exhaust fuel gas can be reduced to below the allowable temperature of the lower tube sheet.

[0109] (IV characteristics of cell stack) The relationship between the operating temperature and IV characteristics of an SOFC is shown in Figure 6. In this figure, the horizontal axis represents the cell current (A) and the vertical axis represents the cell voltage (V).

[0110] According to Figure 6, as the cell current increases, the cell voltage decreases. This is because the voltage drop due to the internal resistance of the cell increases as the cell current increases. As the cell voltage decreases, the redox potential also decreases, and the oxidation of nickel in the anode progresses, so in SOFCs there is a limit to the current density at which the cell can be operated.

[0111] For the same cell current, a cell stack with a higher temperature will have a higher average voltage than a cell stack with a lower temperature because the conductivity of the solid electrolyte membrane will be higher. Therefore, in order to extract more power from a single cell stack, it is better to have a higher average operating temperature, as long as it does not exceed the allowable temperature.

[0112] (Power generation performance) The power generation performance was predicted for the cell stacks (Examples 1 to 5, Comparative Examples 1 and 2) using the length of the heat transfer section of the fuel gas inlet heat exchanger (L1), the length of the power generation section (L2), and the length of the heat transfer section of the exhaust fuel gas outlet heat exchanger (L3) as parameters.

[0113] The calculation conditions are as follows: Fuel gas (simulated reformed gas): H239.5%+H2O28.4%+CO11.6%+CO220.5% Fuel utilization rate: 60% Air utilization rate: 30% Current density: 0.5A / cm 2 Upper tube sheet temperature: 600°C (the allowable temperature for metal materials) Lower tube sheet temperature: 600°C (the allowable temperature for metal materials) Maximum temperature of power generation section: 950°C (permissible temperature for cell operation) Cell stack effective length: L = sum of L1, L2 and L3 (constant in each case)

[0114] The power generation performance was calculated by subtracting the voltage drop due to ohmic resistance, concentration overvoltage, and reaction overvoltage, calculated from the physical properties such as conductivity at the operating temperature of each of the cell stack constituent materials at an arbitrary current value and their dimensions, from the electromotive force of the cell stack. The diameter of the substrate tube used in the cell stack was uniform in the longitudinal direction. The width of the fuel cell in Examples 1 to 5 and Comparative Examples 1 and 2 was all the same.

[0115] The results are shown in Figure 7. In this figure, the effective cell stack length L is the same for all cells, and L1, L2, and L3 are expressed as length ratios (%) relative to L.

[0116] In Comparative Examples 1 and 2, in which the heat transfer section length (L1) of the fuel gas inlet heat exchange section was shorter than the heat transfer section length (L3) of the fuel gas outlet heat exchange section, the average voltage was below 0.750 V. On the other hand, in Examples 1 to 4, in which L1 was longer than L3, and in Example 5, in which L1 was the same as L3, the average voltage was 0.750 V or higher. When the width of the fuel cell unit is the same, shortening the length of the power generation section reduces the number of fuel cell unit cells included in one cell stack. Reducing the number of fuel cell unit cells also reduces output. These results confirmed that cell stacks in which L1 is the same as L3 or longer than L3 provide higher output.

[0117] 7 is shown in graph form in Fig. 8. According to Fig. 8, the ratio of L1 to L3 (L1 / L3) may be between 1 and 4. It has also been confirmed that the results in Fig. 8 are consistent with the results of a temperature distribution simulation (not shown).

[0118] Third Embodiment In this embodiment, a case where an electrochemical cell stack is used for the co-electrolysis of water vapor and carbon dioxide will be described. The basic configuration is the same as in the first embodiment. The first electrode is replaced with a "hydrogen electrode," the second electrode is replaced with an "oxygen electrode," the electrochemical unit cell is replaced with a "co-electrolysis unit," the reaction unit is replaced with a "co-electrolysis unit," the electrochemical cell stack is replaced with a "co-electrolysis cell stack," the electrochemical cell cartridge is replaced with a "co-electrolysis cell cartridge," and the electrochemical cell module is replaced with a "co-electrolysis cell module."

[0119] The specific materials and manufacturing method of the co-electrolysis single cell are the same as those in the second embodiment. The fuel electrode in the second embodiment can be read as the "hydrogen electrode," the air electrode as the "oxygen electrode," and the fuel gas as the "feed gas."

[0120] The co-electrolysis cell stack, co-electrolysis cell module, and co-electrolysis cell cartridge have the same components as those of the fuel cell stack, fuel cell module, and fuel cell cartridge of the second embodiment, and are designated by the same reference numerals.

[0121] (co-electrolysis cell stack) The co-electrolysis cell stack (hereinafter simply referred to as the cell stack) 101 includes a co-electrolysis section 10 having a co-electrolysis unit cell 105 in the center in the longitudinal direction, the co-electrolysis unit cell 105 being formed by stacking a hydrogen electrode 109, a solid electrolyte membrane 111, and an oxygen electrode 113 in that order.

[0122] The cell stack 101 has a raw material gas supply port 11 and a produced gas discharge port 12. The cell stack 101 is provided with a raw material gas inlet heat exchanger 13 and a produced gas outlet heat exchanger 14, which sandwich the co-electrolysis section 10 from both longitudinal sides. The areas (or lengths) of the heat transfer sections of the raw material gas inlet heat exchanger 13 and the produced gas outlet heat exchanger 14 are the same as those in the first embodiment.

[0123] The raw material gas of the cell stack 101 includes water vapor electrolyzed in the co-electrolysis unit cell 105 and a second gas that undergoes a reduction reaction with hydrogen generated by the electrolysis reaction.

[0124] In this example, the second gas is carbon dioxide. If only water vapor and carbon dioxide are supplied as the feed gas, the supply side of the co-electrolytic single cell may become an oxidizing atmosphere, potentially causing oxidation corrosion of the metal material. Therefore, hydrogen gas is included as a reducing gas to maintain a reducing state in the feed gas. Here, the carbon dioxide and hydrogen gas contained in the feed gas may undergo an endothermic reaction according to the reverse water-gas shift reaction (RIW) formula (4) described in the first embodiment on the supply side of the co-electrolytic single cell due to the catalytic action of the metal components in the feed gas inlet heat exchanger 13 and the nickel contained in the substrate tube. CO2+H2=CO+H2O-41.2kJ / mol···(4)

[0125] The materials and manufacturing methods for each component of the cell stack 101 are the same as those in the second embodiment.

[0126] In the water vapor and carbon dioxide co-electrolysis unit cell, the mixed gas flowing through the product gas discharge pipe 209 in the raw gas electrolysis chamber 215 comes into contact with the hydrogen electrode 109 through the porous substrate tube 103. In the hydrogen electrode 109, the water vapor contained in the mixed gas is electrolyzed to produce hydrogen molecules and oxygen ions (O 2- ) is produced, and carbon dioxide is reduced to produce carbon monoxide (see equation (5) below). CO2+3H2O(+electricity)=CO+3H2(+2O2) (endothermic)...(5)

[0127] Furthermore, the produced carbon monoxide undergoes a methanation reaction (see reaction formula (6) below) to produce methane. CO + 3H2 = CH4 + H2O (exothermic) (6)

[0128] In the co-electrolysis reaction of water vapor and carbon dioxide, the heat generated by the above equation (6) can be used to absorb heat in equation (5). Therefore, the energy conversion efficiency of methane production by the co-electrolysis reaction of water vapor and carbon dioxide is approximately 1.5 times higher than that of methane production by the conventional Sabatier reaction (see reaction equation (7) below). CO2+4H2=CH4+2H2O+165kJ / mol...(7)

[0129] However, since the operating temperature of the co-electrolysis cell is as high as about 700 to 900°C, the proportion of methane at the outlet of the co-electrolysis cell is small in terms of chemical equilibrium.

[0130] The product gas discharged from the outlet of the co-electrolytic cell exchanges heat with the oxidizing gas in the product gas outlet heat exchanger, and as its temperature drops, the reactions of equations (6) and (7) proceed due to the catalytic action of the nickel contained in the metal components of the product gas outlet heat exchanger 14 and the substrate tube, increasing the methane composition and generating heat. For this reason, the heat transfer area of ​​the product gas outlet heat exchanger may be appropriately set according to the supply temperature and flow rate of the oxidizing gas so that the product gas temperature at the outlet of the product gas outlet heat exchanger is below the allowable temperature.

[0131] On the other hand, the oxygen ions pass through the solid electrolyte membrane 111 due to the potential difference, move to the oxygen electrode 113, release electrons, and become oxygen molecules (see reaction formula (8) below). The generated oxygen is discharged to the outside together with the oxidizing gas supplied to the oxygen electrode. 2O 2- =O2+4e - ···(8)

[0132] The oxidizing gas is not directly involved in the co-electrolysis reaction, but it supplies the heat necessary for the electrolysis reaction (endothermic) and discharges excess heat generated by the electrolysis reaction. It is usually a gas containing approximately 15% to 30% oxygen, and air is a typical example, but other gases that can be used include a mixture of combustion exhaust gas and air, a mixture of oxygen and air, and inert gases such as nitrogen.

[0133] The lead film 115 supplies DC power to the plurality of co-electrolysis single cells 105 connected in series by the interconnectors 107 .

[0134] When external power is supplied between the hydrogen electrode 109 and the oxygen electrode 113 via the lead film 115, part of the high-temperature raw material gas supplied to the hydrogen electrode 109 receives electrons and is electrolyzed. For example, part of the water vapor receives electrons and is separated into hydrogen and oxygen ions, generating hydrogen. The separated oxygen ions pass through the inside of the solid electrolyte membrane 111 and move to the oxygen electrode 113, where they release electrons and become oxygen.

[0135] (Co-electrolytic cell cartridge) The co-electrolysis cell cartridge (hereinafter, cartridge) 203 includes a plurality of cell stacks 101, a raw material gas electrolysis chamber 215, a raw material gas supply header 217, a product gas discharge header 219, an oxidizing gas (air) supply header 221, and an oxidizing gas discharge header 223. The cartridge 203 also includes an upper tube plate 225a, a lower tube plate 225b, an upper insulator 227a, and a lower insulator 227b. In this embodiment, the raw material gas supply header 217, the product gas discharge header 219, the oxidizing gas supply header 221, and the oxidizing gas discharge header 223 are arranged as shown in FIG. 2, thereby forming a structure in which the raw material gas and the oxidizing gas flow in opposing directions inside and outside the cell stack 101. However, this is not necessarily required. For example, the raw material gas and the oxidizing gas may flow in parallel inside and outside the cell stack 101, or the oxidizing gas may flow in a direction perpendicular to the longitudinal direction of the cell stack 101.

[0136] The raw material gas inlet heat exchanger 13 of the cell stack 101 extends from the lower surface of the upper tube plate 225a to the upper end of the uppermost co-electrolysis unit cell 105 among the multiple co-electrolysis unit cells 105. The product gas outlet heat exchanger 14 of the cell stack 101 extends from the lower end of the lowermost co-electrolysis unit cell 105 among the multiple co-electrolysis unit cells 105 to the upper surface of the lower tube plate 225b.

[0137] The raw material gas electrolysis chamber 215 is a region formed between the upper insulator 227a and the lower insulator 227b. This raw material gas common electrolysis chamber 215 is a region in which the common electrolysis unit cells 105 of the cell stack 101 are arranged, and is a region in which the raw material gas is electrolyzed to produce a product gas. The temperature near the center of the raw material gas common electrolysis chamber 215 in the longitudinal direction of the cell stack 101 may be monitored by a temperature measurement unit (such as a temperature sensor or a thermocouple), and during steady-state operation of the common electrolysis cell module 201, a high-temperature atmosphere of approximately 700°C to 1000°C is produced.

[0138] The raw material gas supply header 217 is an area surrounded by the upper casing 229a and upper tube plate 225a of the cartridge 203, and is connected to the raw material gas supply branch pipe 207a via raw material gas supply holes 231a provided in the upper part of the upper casing 229a. The multiple cell stacks 101 are joined to the upper tube plate 225a by upper seal members 237a, and the raw material gas supply header 217 guides the raw material gas, which is supplied from the raw material gas supply branch pipe 207a via the raw material gas supply holes 231a, into the interiors of the substrate tubes 103 of the multiple cell stacks 101 at a substantially uniform flow rate, thereby substantially uniforming the hydrogen generation performance of the multiple cell stacks 101.

[0139] The produced gas discharge header 219 is an area surrounded by the lower casing 229b and lower tube plate 225b of the cartridge 203, and is connected to the produced gas discharge branch pipe 209a by produced gas discharge holes 231b provided in the lower casing 229b. The multiple cell stacks 101 are joined to the lower tube plate 225b by a lower seal member 237b, and the produced gas discharge header 219 collects the exhaust raw material gas (produced gas containing unreacted raw material gas) that passes through the insides of the base tubes 103 of the multiple cell stacks 101 and is supplied to the produced gas discharge header 219, and leads it to the produced gas discharge branch pipe 209a via the produced gas discharge holes 231b.

[0140] The oxidizing gas supply pipe (not shown) branches into oxidizing gas supply branch pipes (not shown) that supply a predetermined flow rate of oxidizing gas corresponding to the operating temperature of the module 201 to the plurality of cartridges 203. The oxidizing gas supply header 221 is an area surrounded by the lower casing 229b, lower tube plate 225b, and lower insulator 227b of the cartridge 203, and is connected to an oxidizing gas supply branch pipe (not shown) through an oxidizing gas supply hole 233a provided on the side surface of the lower casing 229b. The oxidizing gas supply header 221 guides the predetermined flow rate of oxidizing gas supplied from the oxidizing gas supply branch pipe (not shown) through the oxidizing gas supply hole 233a to the raw material gas electrolysis chamber 215 via an oxidizing gas supply gap 235a (described later).

[0141] The oxidizing gas discharge header 223 is an area surrounded by the upper casing 229a, upper tube plate 225a, and upper heat insulator 227a of the cartridge 203, and is connected to an oxidizing gas discharge branch pipe (not shown) through oxidizing gas discharge holes 233b provided on the side surface of the upper casing 229a. The oxidizing gas discharge header 223 guides the exhaust oxidizing gas supplied to the oxidizing gas discharge header 223 from the raw material gas common electrolysis chamber 215 through an oxidizing gas discharge gap 235b (described later) to the oxidizing gas discharge branch pipe (not shown) through the oxidizing gas discharge holes 233b.

[0142] The upper tube plate 225a is fixed to the side plate of the upper casing 229a between the top plate of the upper casing 229a and the upper insulator 227a so that the upper tube plate 225a, the top plate of the upper casing 229a, and the upper insulator 227a are approximately parallel to each other. The upper tube plate 225a has a number of holes corresponding to the number of cell stacks 101 provided in the cartridge 203, and the cell stacks 101 are inserted into the holes. The upper tube plate 225a airtightly supports one end of the multiple cell stacks 101 via either or both of an upper seal member 237a and an adhesive member, and separates the raw material gas supply header 217 from the oxidizing gas discharge header 223. The oxidizing gas discharge gap 235b is a region (heat transfer section L1) where heat exchange between the supply steam (raw material gas) and the oxidizing gas takes place.

[0143] The upper heat insulator 227a is disposed at the lower end of the upper casing 229a so that the upper heat insulator 227a, the top plate of the upper casing 229a, and the upper tube plate 225a are substantially parallel to each other, and is fixed to the side plates of the upper casing 229a. The upper heat insulator 227a has a plurality of holes formed therein corresponding to the number of cell stacks 101 provided in the cartridge 203. The diameters of the holes are set larger than the outer diameters of the cell stacks 101. The upper heat insulator 227a has oxidizing gas discharge gaps 235b formed between the inner surfaces of the holes and the outer surfaces of the cell stacks 101 inserted through the upper heat insulator 227a.

[0144] The upper heat insulator 227a separates the raw material gas common electrolysis chamber 215 from the oxidizing gas discharge header 223, and prevents the atmosphere around the upper tube sheet 225a from becoming hot, thereby reducing its strength and increasing corrosion caused by the oxidizing agent contained in the oxidizing gas. Furthermore, a metal material with high temperature resistance, such as a Ni-based alloy, may be used to prevent thermal deformation of the upper tube sheet 225a and other components due to temperature differences when the upper tube sheet 225a and other components are exposed to high temperatures within the raw material gas common electrolysis chamber 215. The upper heat insulator 227a guides the exhaust oxidizing gas, which has been exposed to high temperatures after passing through the raw material gas common electrolysis chamber 215, through the oxidizing gas discharge gap 235b and into the oxidizing gas discharge header 223.

[0145] According to this embodiment, the structure of the cartridge 203 described above allows the raw material gas and the oxidizing gas to flow in opposite directions inside and outside the cell stack 101. As a result, heat is exchanged between the exhaust oxidizing gas and the raw material gas supplied to the raw material gas common electrolysis chamber 215 through the inside of the base tube 103, and the exhaust oxidizing gas is cooled to a temperature at which stress damage to the upper tube plate 225a and other components made of a metallic material can be prevented, and the raw material gas is supplied to the oxidizing gas discharge header 223. The raw material gas is also heated by heat exchange with the exhaust oxidizing gas discharged from the raw material gas common electrolysis chamber 215, and is supplied to the raw material gas common electrolysis chamber 215. As a result, raw material gas preheated to a temperature required for the electrolysis reaction can be supplied to the raw material gas common electrolysis chamber 215 without using a heater or the like.

[0146] The lower tube plate 225b is fixed to the side plate of the lower casing 229b between the bottom plate of the lower casing 229b and the lower insulator 227b so that the lower tube plate 225b, the bottom plate of the lower casing 229b, and the lower insulator 227b are approximately parallel to each other. The lower tube plate 225b has a number of holes corresponding to the number of cell stacks 101 provided in the cartridge 203, and the cell stacks 101 are inserted into the holes. The lower tube plate 225b airtightly supports the other ends of the multiple cell stacks 101 via either or both of a lower seal member 237b and an adhesive member, and also separates the produced gas discharge header 219 from the oxidizing gas supply header 221.

[0147] The lower heat insulator 227b is disposed at the upper end of the lower casing 229b so that the lower heat insulator 227b, the bottom plate of the lower casing 229b, and the lower tube plate 225b are substantially parallel to each other, and is fixed to the side plate of the lower casing 229b. The lower heat insulator 227b has a plurality of holes formed therein corresponding to the number of cell stacks 101 provided in the cartridge 203. The diameters of the holes are set larger than the outer diameters of the cell stacks 101. The lower heat insulator 227b has an oxidizing gas supply gap 235a formed between the inner surface of the hole and the outer surface of the cell stack 101 inserted through the lower heat insulator 227b. The oxidizing gas supply gap 235a is a region (heat transfer section L3) where heat exchange between hydrogen gas (produced hydrogen) and oxidizing gas takes place.

[0148] The lower heat insulator 227b separates the raw material gas common electrolysis chamber 215 from the oxidizing gas supply header 221, and prevents the atmosphere surrounding the lower tube sheet 225b from becoming hot, thereby reducing its strength and increasing corrosion caused by the oxidizing agent contained in the oxidizing gas. Furthermore, a metal material with high temperature resistance, such as a Ni-based alloy, may be used to prevent thermal deformation of the lower tube sheet 225b and other components due to temperature differences when the lower tube sheet 225b and other components are exposed to high temperatures within the raw material gas common electrolysis chamber 215. The lower heat insulator 227b guides the oxidizing gas supplied to the oxidizing gas supply header 221 to the raw material gas common electrolysis chamber 215 by passing it through the oxidizing gas supply gap 235a.

[0149] Heat exchange between the supply steam and the oxidizing gas in the upper heat exchange unit 13 occurs when the oxidizing gas passes through the oxidizing gas discharge gap 235b (heat transfer unit L1 of the upper heat exchange unit). Note that heat exchange in the region of the upper heat exchange unit 13 other than the heat transfer unit L1 (the region from the end (outer end) of the common electrolytic cell 105 on the source gas supply port (steam supply port) 11 side formed in the cell stack 101 to the oxidizing gas discharge gap 235b and the portion penetrating the oxidizing gas discharge header 223) is slight and can be ignored.

[0150] The thickness of the upper heat insulator 227a may be changed as appropriate, and increasing the thickness of the upper heat insulator 227a can improve heat exchange efficiency. The volume of the oxidizing gas discharge header 223 may be constant regardless of the heat transfer section area (length) of the upper heat exchange section 13.

[0151] Heat exchange between the produced hydrogen and the oxidizing gas in the lower heat exchange unit 14 occurs when the oxidizing gas passes through the oxidizing gas supply gap 235a (heat transfer unit L3 of the lower heat exchange unit). Note that heat exchange in areas of the lower heat exchange unit 14 other than the heat transfer unit L3 (the area from the end (outer end) of the common electrolytic cell 105 on the produced hydrogen outlet (hydrogen gas outlet) 12 side formed in the cell stack 101 to the oxidizing gas supply gap 235a and the portion penetrating the oxidizing gas supply header 221) is slight and can be ignored.

[0152] The thickness of the lower heat insulator 227b may be changed as appropriate, and increasing the thickness of the lower heat insulator 227b can improve the heat exchange efficiency. The volume of the oxidizing gas supply header 221 may be constant regardless of the heat transfer section area (length) of the lower heat exchange section 14.

[0153] According to this embodiment, the structure of the cartridge 203 described above allows the raw material gas and the oxidizing gas to flow in opposite directions inside and outside the cell stack 101. As a result, the produced gas that has passed through the inside of the base tube 103 and the raw material gas common electrolysis chamber 215 exchanges heat with the oxidizing gas supplied to the raw material gas common electrolysis chamber 215, and is cooled to a temperature that prevents damage due to stress to the lower tube plate 225b made of a metal material, and is supplied to the produced gas discharge header 219. The oxidizing gas is also heated by heat exchange with the produced gas, and is supplied to the raw material gas common electrolysis chamber 215. As a result, the oxidizing gas heated to a temperature required for the electrolysis reaction can be supplied to the raw material gas common electrolysis chamber 215 without using a heater or the like.

[0154] (Co-electrolysis cell module) Similar to the second embodiment, the co-electrolytic cell module (hereinafter referred to as the module) includes multiple cartridges (co-electrolytic cell cartridges) 203 and a module container 205 that houses the multiple cartridges 203. The module includes a raw material gas supply pipe 207, multiple raw material gas supply branch pipes 207a, a product gas discharge pipe 209, and multiple product gas discharge branch pipes 209a. The module 201 also includes an oxidizing gas supply pipe (not shown) and multiple oxidizing gas supply branch pipes (not shown).

[0155] The raw material gas supply pipe 207 is provided inside the module container 205, and is connected to a raw material gas supply unit that supplies raw material gas at a predetermined gas composition and flow rate corresponding to the amount of hydrogen generated by the module 201, and is also connected to multiple raw material gas supply branch pipes 207a. This raw material gas supply pipe 207 branches and guides water vapor at a predetermined flow rate, supplied from the raw material gas supply unit, to the multiple raw material gas supply branch pipes 207a. Furthermore, the raw material gas supply branch pipe 207a is connected to the raw material gas supply pipe 207, and is also connected to raw material gas supply holes 231a of the multiple cartridges 203. This raw material gas supply branch pipe 207a guides the raw material gas supplied from the raw material gas supply pipe 207 to the multiple cartridges 203 at a substantially uniform flow rate, thereby substantially uniforming the electrolysis voltage of the multiple cartridges 203.

[0156] The produced gas discharge branch pipe 209a is connected to the produced gas discharge holes 231b of the multiple cartridges 203 and is also connected to the produced gas discharge pipe 209. This produced gas discharge branch pipe 209a guides the waste raw material gas discharged from the cartridges 203 to the produced gas discharge pipe 209. The produced gas discharge pipe 209 is also connected to the multiple produced gas discharge branch pipes 209a, and a portion of the produced gas discharge pipe 209 is disposed outside the module container 205. This produced gas discharge pipe 209 guides the produced gas, which is discharged at a substantially uniform flow rate from the produced gas discharge branch pipe 209a, to the outside of the module container 205.

[0157] The module container 205 is operated with an internal pressure of atmospheric pressure to several MPa and a surface temperature of atmospheric temperature to approximately 300° C., and is preferably made of carbon steel, for example, from the viewpoint of cost reduction.

[0158] Here, in this embodiment, a configuration in which multiple cartridges 203 are grouped together and stored in a modular container 205 is described, but this is not limited to this, and for example, the cartridges 203 can also be stored in a modular container 205 without being grouped together.

[0159] The DC power required for the electrolysis reaction is converted to a predetermined voltage by a power converter such as a power conditioner and then supplied to the module. The power supplied to the module is distributed according to the number of cartridges connected in series and in parallel. In each cartridge 203, power is supplied to a power supply member (not shown) via a power supply plate (not shown), and is then passed to the vicinity of the end of the cell stack 101 via lead films 115 made of Ni / YSZ or the like provided on the multiple common electrolysis single cells 105, before being supplied to the electrolysis cells.

[0160] <Additional Notes> The electrochemical cell stack, the cartridge and module including the same, and the manufacturing method thereof, fuel cell stack, and electrolysis cell stack described in the above-described embodiments can be understood, for example, as follows.

[0161] The electrochemical cell stack (101) according to a first aspect of the present disclosure includes a reaction section (10) having an electrochemical unit cell (105) formed by stacking a first electrode (109), a solid electrolyte membrane (111), and a second electrode (113) in this order, a raw material gas supply port (11) for supplying a raw material gas to the first electrode of the reaction section, a product gas discharge port (12) for discharging a product gas generated in the reaction section, and a catalyst component that causes an endothermic reaction of the raw material gas, and the raw material gas is discharged from the reaction section. The reactor is provided with a raw material gas inlet heat exchanger (13) on the supply port side, where heat exchange occurs between the raw material gas and an oxidizing gas supplied to the second electrode side, and a product gas outlet heat exchanger (14) on the product gas outlet side of the reaction section, where heat exchange occurs between the product gas and an oxidizing gas supplied to the second electrode side, wherein the heat transfer area of ​​the raw material gas inlet heat exchanger is the same as or larger than the heat transfer area of ​​the product gas outlet heat exchanger.

[0162] In an electrochemical cell stack in which the heat transfer area of ​​the raw gas inlet heat exchanger is larger than that of the product gas outlet heat exchanger, even if there is a temperature drop due to an endothermic reaction that occurs before the gas reaches the reaction section (electrochemical single cell), the gas supplied to the electrochemical single cell can be raised to the desired temperature by preheating it in the raw gas inlet heat exchanger.

[0163] In the electrochemical cell stack according to a second aspect of the present disclosure, in the first aspect, the ratio of the heat transfer area of ​​the raw material gas inlet heat exchanger to the heat transfer area of ​​the product gas outlet heat exchanger is greater than or equal to 1 and is less than or equal to 4.

[0164] In an electrochemical cell stack with the above ratio, a sufficiently preheated raw material gas can be supplied to the reaction section, and the temperature of the produced gas (exhaust raw material gas) can be lowered to within the allowable temperature range of the lower tube plate.

[0165] An electrochemical cell stack according to a third aspect of the present disclosure is the electrochemical cell stack of the first or second aspect, wherein the raw material gas is any one of a hydrocarbon fuel, ammonia gas, and a mixed gas of carbon dioxide gas and water vapor.

[0166] The above-mentioned raw material gases are all gases that undergo endothermic reactions in the raw material gas inlet heat exchange section.

[0167] An electrochemical cell cartridge (203) according to a fourth aspect of the present disclosure comprises an electrolysis cell stack according to any one of the first to third aspects; a raw gas inlet side insulator having a hole through which the raw gas supply port side end of the electrochemical cell stack is inserted and which forms a gap between the raw gas inlet heat exchanger of the electrochemical cell stack and the raw gas inlet heat exchanger of the electrochemical cell stack, and a product gas outlet side insulator having a hole through which the product gas outlet side end of the electrochemical cell stack is inserted and which forms a gap between the raw gas inlet side insulator and the product gas outlet heat exchanger of the electrochemical cell stack, wherein the region forming the gap with the hole in the raw gas inlet side insulator is the heat transfer portion of the raw gas inlet heat exchanger, and the region forming the gap with the hole in the product gas outlet side insulator is the heat transfer portion of the product gas outlet heat exchanger.

[0168] An electrochemical cell module (201) according to a fifth aspect of the present disclosure includes the electrolytic cell cartridge according to the fourth aspect.

[0169] A sixth aspect of the present disclosure provides a method for manufacturing an electrochemical cell stack comprising: a reaction section having an electrochemical unit cell formed by stacking a first electrode, a solid electrolyte membrane, and a second electrode in that order; a raw material gas supply port for supplying a raw material gas to the first electrode of the reaction section; a product gas outlet port for discharging a product gas generated in the reaction section; a raw material gas inlet heat exchanger containing a catalytic component that causes an endothermic reaction with the raw material gas, the raw material gas inlet heat exchanger being located closer to the raw material gas supply port than the reaction section and exchanging heat between the raw material gas and an oxidizing gas supplied to the second electrode side; and a product gas outlet heat exchanger being located closer to the raw material gas outlet port than the reaction section and exchanging heat between the product gas and the oxidizing gas supplied to the second electrode side, wherein the heat transfer area of ​​the raw material gas inlet heat exchanger is formed to be the same as or larger than the heat transfer area of ​​the product gas outlet heat exchanger.

[0170] a fuel cell stack according to a seventh aspect of the present disclosure, comprising: a power generation unit having a single fuel cell cell formed by stacking an anode, a solid electrolyte membrane, and an air cathode in that order; a fuel gas supply port for supplying fuel gas to the anode of the power generation unit; a product gas outlet port for discharging product gas generated in the power generation unit; a fuel gas inlet heat exchanger containing a catalyst for endothermic reaction of the fuel gas, the fuel gas being exchanged between the fuel gas and an oxidizing gas supplied to the air electrode side, on the fuel gas supply port side of the power generation unit; and an exhaust fuel gas outlet heat exchanger for exchanging heat between the product gas and the oxidizing gas supplied to the air electrode side, on the product gas outlet side of the power generation unit, wherein the heat transfer area of ​​the fuel gas inlet heat exchanger is the same as or larger than the heat transfer area of ​​the exhaust fuel gas outlet heat exchanger.

[0171] The fuel cell stack described above can extract a large amount of power from a single cell stack.

[0172] a feed gas inlet heat exchanger that includes a catalyst for endothermic reaction of the feed gas, the feed gas inlet heat exchanger being located closer to the feed gas inlet than the co-electrolysis unit and performing heat exchange between the feed gas and an oxidizing gas supplied to the oxygen electrode side; and a product gas outlet heat exchanger that is located closer to the product gas outlet than the co-electrolysis unit and performing heat exchange between the product gas and the oxidizing gas supplied to the oxygen electrode side, the product gas inlet heat exchanger being located closer to the product gas outlet than the co-electrolysis unit and performing heat exchange between the product gas and the oxidizing gas supplied to the oxygen electrode side, wherein the heat transfer area of ​​the feed gas inlet heat exchanger is the same as or larger than the heat transfer area of ​​the product gas outlet heat exchanger.

[0173] When the above-mentioned co-electrolysis cell stack is used to produce methane through the co-electrolysis reaction of water vapor and carbon dioxide, the energy conversion efficiency is approximately 1.5 times higher than that of methane production through the conventional Sabatier reaction using hydrogen and carbon dioxide as raw materials. [Explanation of symbols]

[0174] 10 Reaction section (power generation section, co-electrolysis section) 11 Raw material gas supply port (fuel gas supply port) 12 Produced gas outlet (exhaust fuel gas outlet) 13 Raw material gas inlet heat exchange section (fuel gas inlet heat exchange section, upper heat exchange section) 14 Produced gas outlet heat exchange section (exhaust fuel gas outlet heat exchange section, lower heat exchange section) 101 Electrochemical cell stack (fuel cell stack, co-electrolysis cell stack) 103 Base tube 105 Electrochemical single cell (fuel cell, co-electrolysis single cell) 107 Interconnector 109 Fuel electrode (hydrogen electrode, first electrode) 111 Solid electrolyte membrane 113 Air electrode (oxygen electrode, second electrode) 115 Lead Film 201 Modules (electrochemical cell modules, fuel cell modules, co-electrolysis cell modules) 203 Cartridges (electrochemical cell cartridges, fuel cell cartridges, co-electrolysis cell modules) 205 Modular Container 207 Fuel gas supply pipe (raw gas supply pipe) 207a Fuel gas supply branch pipe (raw material gas supply branch pipe) 209 Fuel gas exhaust pipe (produced gas exhaust pipe) 209a Fuel gas discharge branch pipe (produced gas discharge branch pipe) 215 Power generation room (raw gas electrolysis room / raw gas common electrolysis room) 217 Fuel gas supply header (raw material gas supply header) 219 Fuel gas discharge header (produced gas discharge header) 221 Oxidizing gas supply header 223 Oxidizing gas discharge header 225a Upper tube plate 225b Lower tube sheet 227a Upper insulation 227b Lower insulation 229a Upper casing 229b Lower casing 231a Fuel gas supply hole (raw material gas supply hole) 231b Fuel gas exhaust hole (produced gas exhaust hole) 233a Oxidizing gas supply hole 233b Oxidizing gas exhaust hole 235a Oxidizing gas supply gap 235b Oxidizing gas exhaust gap 237a Upper seal member 237b Lower seal member

Claims

1. a reaction section having an electrochemical unit cell formed by stacking a first electrode, a solid electrolyte membrane, and a second electrode in this order; a raw material gas supply port for supplying a raw material gas to the first electrode of the reaction section; a product gas outlet for discharging a product gas generated in the reaction section; a raw material gas inlet heat exchange section that contains a catalyst component that causes an endothermic reaction with the raw material gas, and that exchanges heat between the raw material gas and an oxidizing gas supplied to the second electrode side, on the raw material gas supply port side of the reaction section; a product gas outlet heat exchanger located closer to the product gas outlet than the reaction section and performing heat exchange between the product gas and an oxidizing gas supplied to the second electrode side; Equipped with an electrochemical cell stack in which the heat transfer area of ​​the raw material gas inlet heat exchanger is the same as or larger than the heat transfer area of ​​the product gas outlet heat exchanger;

2. 2. The electrochemical cell stack according to claim 1, wherein a ratio of the heat transfer area of ​​the raw material gas inlet heat exchanger to the heat transfer area of ​​the product gas outlet heat exchanger is greater than or equal to 1 and less than or equal to 4.

3. 2. The electrochemical cell stack according to claim 1, wherein the raw material gas is any one of a hydrocarbon fuel, ammonia gas, and a mixed gas of carbon dioxide gas and water vapor.

4. The electrochemical cell stack according to any one of claims 1 to 3; a raw material gas inlet side insulator having a hole through which an end portion of the electrochemical cell stack on the raw material gas supply port side is inserted, the raw material gas inlet side insulator forming a gap through which the oxidizing gas passes between the raw material gas inlet heat exchange unit of the electrochemical cell stack and the raw material gas inlet side insulator; a product gas outlet side insulator having a hole through which an end of the electrochemical cell stack on the product gas outlet side is inserted, the product gas outlet side insulator forming a gap through which the oxidizing gas passes between the product gas outlet side insulator and the product gas outlet heat exchanger of the electrochemical cell stack; Equipped with a region where the gap is formed with the hole of the raw material gas inlet side heat insulator is a heat transfer portion of the raw material gas inlet heat exchange unit, An electrochemical cell cartridge in which the region forming the gap with the holes in the product gas outlet side heat insulator is the heat transfer portion of the product gas outlet heat exchanger.

5. An electrochemical cell module comprising the electrochemical cell cartridge according to claim 4.

6. a reaction section having an electrochemical unit cell formed by stacking a first electrode, a solid electrolyte membrane, and a second electrode in this order; a raw material gas supply port for supplying a raw material gas to the first electrode of the reaction section; a product gas outlet for discharging a product gas generated in the reaction section; a raw material gas inlet heat exchange section that contains a catalyst component that causes an endothermic reaction with the raw material gas, and that exchanges heat between the raw material gas and an oxidizing gas supplied to the second electrode side, on the raw material gas supply port side of the reaction section; a product gas outlet heat exchanger located closer to the product gas outlet than the reaction section and performing heat exchange between the product gas and an oxidizing gas supplied to the second electrode side; A method for manufacturing an electrochemical cell stack comprising: a heat transfer section area of ​​the raw material gas inlet heat exchanger section that is equal to or larger than the heat transfer section area of ​​the product gas outlet heat exchanger section;

7. a power generation section having a fuel cell unit cell formed by stacking a fuel electrode, a solid electrolyte membrane, and an air electrode in this order; a fuel gas supply port for supplying a fuel gas to the fuel electrode of the power generation unit; an exhaust fuel gas outlet for discharging the exhaust fuel gas generated in the power generation unit; a fuel gas inlet heat exchanger that includes a catalyst component that causes an endothermic reaction with the fuel gas, and that exchanges heat between the fuel gas and an oxidizing gas supplied to the air electrode side, on the fuel gas supply port side of the power generation unit; an exhaust fuel gas outlet heat exchanger located closer to the exhaust fuel gas outlet than the power generation unit and performing heat exchange between the exhaust fuel gas and an oxidizing gas supplied to the air electrode side; Equipped with A fuel cell stack in which the heat transfer area of ​​the fuel gas inlet heat exchanger is the same as or larger than the heat transfer area of ​​the exhaust fuel gas outlet heat exchanger.

8. a co-electrolysis unit having a co-electrolysis unit cell formed by stacking a hydrogen electrode, a solid electrolyte membrane, and an oxygen electrode in this order; a raw material gas supply port for supplying a raw material gas to the hydrogen electrode of the co-electrolysis section; a product gas outlet for discharging the product gas generated in the co-electrolysis section; a raw material gas inlet heat exchanger section that contains a catalytic component that causes an endothermic reaction with the raw material gas, and that exchanges heat between the raw material gas and an oxidizing gas supplied to the oxygen electrode side, on the raw material gas supply port side of the co-electrolysis section; a product gas outlet heat exchange section, which is located closer to the product gas outlet than the co-electrolysis section and which exchanges heat between the product gas and an oxidizing gas supplied to the oxygen electrode side; Equipped with a co-electrolysis cell stack in which the heat transfer area of ​​the raw material gas inlet heat exchanger is the same as or larger than the heat transfer area of ​​the product gas outlet heat exchanger.

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