Electrolytic cell cartridge and method for manufacturing same

Abstract

The purpose of the present disclosure is to suppress steam oxidation of a power feeding member in an electrolytic cell cartridge. An electrolytic cell cartridge (203) according to the present disclosure is provided with: a plurality of electrolytic cell stacks (101) having electrolytic cells (105) for electrolyzing steam; and power feeding plates (11a, 11b) which have holes for inserting the electrolytic cell stacks and which electrically connect the plurality of electrolytic cell stacks when the electrolytic cell stacks are inserted in the holes. The power feeding plates are each provided with a plate-like stainless-steel base material having holes for inserting the electrolytic cell stacks, and a steam oxidation resistant layer that covers the surface of the base material. The steam oxidation resistant layer is made of a material having steam oxidation resistance greater than that of the base material.

Description

Electrolytic cell cartridge and method of manufacturing same

[0001] The present disclosure relates to an electrolysis cell cartridge and a manufacturing method thereof, and in particular to an electrolysis cell cartridge applied to a solid oxide electrolysis cell (SOEC) that electrolyzes high-temperature steam, and a manufacturing method thereof.

[0002] In recent years, in order to achieve carbon neutrality, ２ There is a need to develop an inexpensive, large-capacity hydrogen production system that does not emit CO2.

[0003] Water electrolysis, which electrochemically decomposes water to produce hydrogen and oxygen, is a hydrogen production method that does not involve carbon dioxide emissions and has excellent environmental properties. There are various methods, such as alkaline electrolysis, which electrolyzes liquid water, solid polymer electrolysis, and steam electrolysis, which electrolyzes water vapor.

[0004] Among these, a solid oxide electrolysis cell (SOEC; hereinafter referred to as "electrolysis cell") that electrolyzes high-temperature steam uses ceramics with oxygen ion conductivity, such as yttria-stabilized zirconia, as an electrolyte, and can utilize the thermal energy of high-temperature steam as part of the energy required for the electrolysis reaction, making it possible to produce hydrogen more efficiently than other electrolysis methods. ２ Co-electrolysis is also possible, in which a mixed gas of hydrogen and carbon dioxide is supplied to the electrolysis cell, and the hydrogen and carbon dioxide produced by electrolysis are reacted in the electrolysis cell to directly produce carbon monoxide (CO) and hydrocarbon compounds.

[0005] Furthermore, some solid oxide electrolysis cells are being developed as reversible solid oxide electrochemical cells (RSOCs; hereinafter referred to as "reversible cells") that have the two-way function of producing hydrogen and oxygen through a reverse reaction when supplied with external electric power and high-temperature steam, and also generating electricity as a fuel cell.

[0006] Patent Document 1 discloses a hydrogen generation system equipped with a cylindrical cell stack in which a plurality of electrolytic cells, each having a hydrogen electrode, a solid electrolyte membrane, and an oxygen electrode, are arranged on a substrate tube. In this hydrogen generation system, a plurality of cell stacks are assembled (formed into a cartridge) and used.

[0007] The electrolytic reaction in an SOEC is an endothermic reaction. Therefore, compared to a solid oxide fuel cell (SOFC) for generating electricity as described in Patent Document 2, an SOEC can apply a higher current than an SOFC. For cells with the same specifications, an SOEC can apply a current several times higher than an SOFC.

[0008] Patent No. 7282968 Patent No. 5106884

[0009] In the SOFC of Patent Document 2, a plurality of cell stacks are electrically connected by thin plate current collecting members. The use of such thin plates as power supply members for the cell stacks of the SOFC is being considered.

[0010] However, in SOECs, which carry a higher current than SOFCs, self-heating due to the resistance of the power supply members increases in proportion to the square of the current value when current flows horizontally through the power supply members, resulting in a larger temperature rise. Therefore, if the current collecting members used in SOFCs are used in SOECs as they are, the temperature of the power supply members may rise to an unacceptable level (over 650°C) from the standpoint of corrosion and thermal stress. This limits the full performance of the cell stack, so measures are required.

[0011] Furthermore, the power supply members of an SOEC are exposed to an atmosphere containing a high concentration of water vapor, which is the raw material for electrolysis. Therefore, when temperatures exceed a certain level (for example, 500°C or higher for a SUS304 power supply plate), water vapor oxidation accelerates. As water vapor oxidation progresses, oxide scale formation and thinning of the power supply members occur. The formation of oxide scale increases the resistance of the joint with the cell stack. When thinning occurs, the cross-sectional area of ​​the power supply members (thin plates) decreases, increasing resistance and leading to further temperature increases.

[0012] The present disclosure has been made in consideration of the above circumstances, and aims to provide an electrolytic cell cartridge that can suppress steam oxidation of the power supply member in order to solve the problem of thinning of the power supply member due to steam oxidation.

[0013] The present disclosure aims to provide an electrolytic cell cartridge that can suppress the temperature rise of the power supply member due to steam oxidation within an acceptable level in order to solve the problem of thinning of the power supply member due to steam oxidation.

[0014] In order to solve the above problems, the electrolytic cell cartridge and the method for manufacturing the same of the present disclosure employ the following measures.

[0015] One aspect of the present disclosure provides an electrolytic cell cartridge comprising a plurality of electrolytic cell stacks each having an electrolytic cell that electrolyzes water vapor, and a power supply plate having holes for inserting the electrolytic cell stacks, the electrolytic cell stacks being inserted into the holes to electrically connect the plurality of electrolytic cell stacks, wherein the power supply plate comprises a stainless steel plate-shaped substrate having holes for inserting the electrolytic cell stacks, and a water vapor oxidation-resistant layer covering the surface of the substrate, and the water vapor oxidation-resistant layer is made of a material that has higher water vapor oxidation resistance than the substrate.

[0016] By providing a water vapor oxidation-resistant layer on the surface of the substrate, the power feeder plate can suppress water vapor oxidation corrosion due to temperature rise caused by self-heating of the power feeder plate when a high current is applied. Because the water vapor oxidation-resistant layer is used as part of the power feeder plate, cost increases can be minimized even if an expensive material is used for the water vapor oxidation-resistant layer. If a material with higher conductivity than stainless steel is used for the water vapor oxidation-resistant layer, the resistivity of the power feeder plate can be reduced, thereby suppressing temperature rise and reducing resistance loss.

[0017] One aspect of the present disclosure provides an electrolytic cell cartridge comprising a plurality of electrolytic cell stacks each having an electrolytic cell for electrolyzing water vapor, and a power supply plate that electrically connects the plurality of electrolytic cell stacks, wherein the power supply plate has a stainless steel plate-shaped substrate having a hole for inserting the electrolytic cell stack, and an emissivity enhancing structure on the surface of the power supply plate for improving the emissivity of the power supply plate.

[0018] By providing an emissivity-enhancing structure, the emissivity of the feeder plate can be increased, which increases the amount of heat transferred (heat dissipation) by radiation from the surface of the feeder plate, making it possible to keep the temperature of the feeder plate at an acceptable level even when a high current is passing through it.

[0019] One aspect of the present disclosure provides a method for manufacturing an electrolytic cell cartridge, comprising: a plurality of electrolytic cell stacks each having an electrolytic cell for electrolyzing water vapor; and a power supply plate that electrically connects the plurality of electrolytic cell stacks in parallel, the power supply plate having a stainless steel plate-shaped substrate with a hole for inserting the electrolytic cell stack; and the method for manufacturing an electrolytic cell cartridge, wherein the surface roughness of the power supply plate is increased by shot blasting or sanding.

[0020] The present disclosure provides an electrolytic cell cartridge that can suppress steam oxidation of a power supply member by providing a steam oxidation-resistant layer on the surface of a substrate.

[0021] The present disclosure provides an electrolytic cell cartridge that can suppress the temperature rise of the power supply member to an acceptable level by providing an emissivity-enhancing structure on the surface of the power supply plate.

[0022] FIG. 1 is a diagram showing an embodiment of a cylindrical electrolysis cell stack according to an embodiment of the present disclosure; FIG. 2 is a diagram showing an embodiment of a cylindrical electrolysis cell cartridge according to an embodiment of the present disclosure; FIG. 3 is a top view of the periphery of the cell stack in FIG. 2; FIG. 4 is a schematic diagram illustrating the relationship between an upper power feed plate and a cell stack; FIG. 5 is a diagram showing a partial cross-sectional view of a power feed plate according to the first embodiment; FIG. 6 is a diagram showing a partial cross-sectional view of another power feed plate according to the first embodiment; FIG. 7 is a diagram showing an embodiment of a cylindrical electrolysis cell module according to an embodiment of the present disclosure; FIG. 8 is a diagram showing a partial cross-sectional view of a power feed plate according to a second embodiment; FIG. 9 is a graph showing the relationship between the power feed plate temperature and the amount of heat transfer from the power feed plate; FIG. 10 is a diagram showing an example of a trial calculation of the effect of increasing the emissivity on reducing the power feed plate temperature; FIG. 11 is a schematic diagram illustrating radiation heat transfer in a lower power feed plate; and FIG. 12 is a diagram showing the relationship between the surface roughness Rz of each test specimen and the emissivity increase rate.

[0023] Hereinafter, an embodiment of an electrolytic cell cartridge and a method for manufacturing the same according to the present disclosure will be described with reference to the drawings.

[0024] The electrolytic cell cartridge according to the present disclosure includes a plurality of electrolytic cell stacks and a power supply plate that electrically connects the plurality of electrolytic cell stacks in parallel.

[0025] 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. 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, the horizontal direction perpendicular to the vertical direction.

[0026] First Embodiment (Electrolysis Cell Stack) First, referring to FIG. 1 , a cylindrical electrolysis cell stack (hereinafter abbreviated as cell stack) using a substrate tube will be described as an example of this embodiment. When a substrate tube is not used, for example, a thick anode electrode may be formed to double as the substrate tube, and the use of a substrate tube is not limited. In this embodiment, the substrate tube is described as being cylindrical, but the cross section of the substrate tube is not necessarily limited to a circular shape and may be, for example, an elliptical shape. A cell stack such as a flat tubular cylinder, in which the peripheral side of a cylinder is vertically crushed, may also be used. Here, FIG. 1 shows one aspect of a cell stack according to this embodiment. The cell stack 101 includes, for example, a cylindrical substrate tube 103, multiple electrolysis cells 105 formed on the outer circumferential surface of the substrate tube 103, and interconnectors 107 formed between adjacent electrolysis cells 105. The electrolysis cell 105 is formed by stacking a hydrogen electrode 109, a solid electrolyte membrane 111, and an oxygen electrode 113. The cell stack 101 includes a lead film 115 electrically connected via an interconnector 107 to the oxygen electrode 113 of the electrolytic cell 105 formed at one end of the electrolytic cell 105 at the extreme end in the axial direction of the substrate tube 103 among a plurality of electrolytic cells 105 formed on the outer peripheral surface of the substrate tube 103, and also includes a lead film 115 electrically connected to the hydrogen electrode 109 of the electrolytic cell 105 formed at the other extreme end.

[0027] The substrate tube 103 is made of a porous material, for example, CaO stabilized ZrO ２(CSZ), a mixture of CSZ and nickel oxide (NiO) (CSZ+NiO), or Y ２ O ３ Stabilized ZrO ２ (YSZ), or MgAl ２ O ４ The base tube 103 supports the electrolytic cell 105, the interconnector 107, and the lead film 115, and also diffuses the water vapor supplied to the inner peripheral surface of the base tube 103 through the pores of the base tube 103 to the hydrogen electrode 109 formed on the outer peripheral surface of the base tube 103.

[0028] The hydrogen electrode 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 hydrogen electrode 109 is 50 μm to 250 μm, and the hydrogen electrode 109 may be formed by screen printing a slurry. 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. This solid electrolyte membrane 111 absorbs oxygen ions (O ２－ ) to the oxygen electrode 113. The thickness of the solid electrolyte membrane 111 located on the surface of the hydrogen electrode 109 is 5 μm to 100 μm, and the solid electrolyte membrane 111 may be formed by screen printing a slurry.

[0029] The oxygen electrode 113 is made of, for example, LaSrMnO ３ based oxides, or LaCoO ３ The oxygen electrode 113 is made of a slurried oxide, and the slurried oxide is applied to the oxygen electrode 113 by screen printing or by using a dispenser. The oxygen electrode 113 may have a two-layer structure. In this case, the oxygen electrode layer (oxygen electrode intermediate layer) on the solid electrolyte membrane 111 side is made of a material that exhibits high ionic conductivity and has excellent catalytic activity. The oxygen electrode intermediate layer may be made of Sm-doped ceria, which exhibits high ionic conductivity, and the oxygen electrode layer (oxygen electrode conductive layer) on the oxygen electrode intermediate layer may be made of Sr- and Ca-doped LaMnO ３ It may be composed of a perovskite oxide such as

[0030] The gas supplied to and discharged from the hydrogen electrode 109 often contains hydrogen in addition to the water vapor used in electrolysis, but in the following explanation, to avoid confusion, the supply gas containing hydrogen will be referred to as "supplied water vapor" and the hydrogen gas containing water vapor discharged from the hydrogen electrode 109 will be referred to as "produced hydrogen."

[0031] By applying a negative voltage to the hydrogen electrode 109 and a positive voltage to the oxygen electrode 113, the water vapor contained in the supplied water vapor receives electrons at the hydrogen electrode 109 and is electrolyzed to form hydrogen molecules and oxygen ions (O ２－ (See reaction formula (1) below.) The hydrogen produced is extracted together with the supplied steam.

[0032] 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 (2) below). The generated oxygen is discharged to the outside together with the oxidizing gas supplied to the oxygen electrode 113. ２ O + 2e － →H ２ +O ２－ ... (1) 20 ２－ →O ２ +4e － ... (2)

[0033] The oxidizing gas is not directly involved in the electrolysis reaction, but 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.

[0034] The interconnector 107 is made of SrTiO ３ M such as １－ｘ L ｘ TiO ３ (M is an alkaline earth metal element, L is a lanthanide element) and lanthanum chromite (LaCrO ３The interconnector 107 is made of a conductive perovskite oxide represented by the formula (I) and is formed into a slurry, which is screen-printed. The interconnector 107 is a dense film that prevents mixing of the supplied water vapor and the oxidizing gas. The interconnector 107 has stable durability and electronic conductivity in both oxidizing and reducing atmospheres. The interconnector 107 electrically connects the oxygen electrode 113 of one electrolytic cell 105 to the hydrogen electrode 109 of the other electrolytic cell 105, thereby connecting the adjacent electrolytic cells 105 in series.

[0035] The lead film 115 must have electronic conductivity and a thermal expansion coefficient close to that of the other materials constituting the cell stack 101. For this reason, a composite material of Ni and a zirconia-based electrolyte material, such as Ni / YSZ, or SrTiO ３ M such as １－ｘ L ｘ TiO ３ (M is an alkaline earth metal element, and L is a lanthanoid element). This lead film 115 applies DC power required for the electrolytic reaction to the ends of the cell stack 101 to the multiple electrolytic cells 105 connected in series by the interconnectors 107. The surface on the oxidizing gas side may be protected with an airtight oxidation-resistant material to prevent oxidation of metal materials such as Ni.

[0036] 2, the electrolysis cell cartridge (hereinafter referred to as cartridge) 203 includes a plurality of cell stacks 101, a steam electrolysis chamber 215, a steam supply header 217, a produced hydrogen discharge header 219, an oxidizing gas (air) supply header 221, an oxidizing gas discharge header 223, and a power supply unit. The cartridge 203 includes an upper tube plate 225a, a lower tube plate 225b, an upper heat insulator 227a, and a lower heat insulator 227b. In this embodiment, the cartridge 203 has a structure in which the water vapor supply header 217, the produced hydrogen discharge header 219, the oxidizing gas supply header 221, and the oxidizing gas discharge header 223 are arranged as shown in Figure 2, so that the supply water vapor and the oxidizing gas flow in opposite directions inside and outside the cell stack 101. However, this is not necessarily required, and for example, the flow may be 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.

[0037] The steam electrolysis chamber 215 is a region formed between the upper insulator 227a and the lower insulator 227b. This steam electrolysis chamber 215 is a region in which the electrolysis cells 105 of the cell stack 101 are arranged, and is a region in which hydrogen is produced by electrolyzing steam. The temperature near the center of the steam electrolysis chamber 215 in the longitudinal direction of the cell stack 101 may be monitored by a temperature measurement unit 620 (such as a temperature sensor or a thermocouple). During steady-state operation of the module 201 (described later), a high-temperature atmosphere of approximately 700°C to 1000°C is created.

[0038] The water vapor 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 a water vapor supply branch pipe 207a (described later) by a water vapor supply pipe 231a provided at the top of the upper casing 229a. The multiple cell stacks 101 are joined to the upper tube plate 225a by an upper seal member 237a, and the water vapor supply header 217 guides water vapor supplied from the water vapor supply branch pipe 207a via the water vapor supply pipe 231a into the interiors of the base 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.

[0039] The produced hydrogen 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 produced hydrogen discharge branch pipe 209a (described later) by a produced hydrogen discharge pipe 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 hydrogen discharge header 219 collects the produced hydrogen that passes through the insides of the base tubes 103 of the multiple cell stacks 101 and is supplied to the produced hydrogen discharge header 219, and guides it to the produced hydrogen discharge branch pipe 209a via the produced hydrogen discharge pipe 231b.

[0040] An oxidizing gas supply header (not shown) branches into oxidizing gas supply branch pipes (not shown) at a predetermined flow rate corresponding to the operating temperature of the module 201, and supplies the oxidizing gas 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 heat insulator 227b of the cartridge 203, and is connected to an oxidizing gas supply branch pipe (not shown) by an oxidizing gas supply pipe 233a provided on the side surface of the lower casing 229b. The oxidizing gas supply header 221 guides the oxidizing gas at a predetermined flow rate, supplied from the oxidizing gas supply branch pipe (not shown) via the oxidizing gas supply pipe 233a, to the steam electrolysis chamber 215 via a lower oxidizing gas penetration 235a (described later).

[0041] 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) by an oxidizing gas discharge pipe 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 steam electrolysis chamber 215 via an oxidizing gas upper penetration 235b (described later) to the oxidizing gas discharge branch pipe (not shown) via the oxidizing gas discharge pipe 233b.

[0042] The power supply plates (power supply sections) are arranged on the upper and lower end sides of the cell stacks 101, respectively, and electrically connect the plurality of cell stacks 101 in parallel.

[0043] The upper power supply plate (upper power supply plate) 11a is disposed inside the steam supply header 217. The upper power supply plate 11a has a plurality of holes for inserting the cell stacks 101. The number of holes provided corresponds to the number of cell stacks 101.

[0044] Figure 3 shows a top view of the cell stack and its surroundings in Figure 2. Figure 4 shows a schematic diagram explaining the relationship between the upper power supply plate and the cell stack. The upper power supply plate supplies power by contacting the lead film 115 of the cell stack 101 with an elastic force (elastic force generating portion 13) generated by bending a part of the power supply plate.

[0045] One end of a conductive member 12a is joined to the upper power supply plate 11a. The other end of the conductive member 12a passes through the upper casing 229a and is connected to an electrode terminal (not shown) provided outside the cartridge 203.

[0046] The lower power supply plate (lower power supply plate) 11b is disposed inside the produced hydrogen discharge header 219. The lower power supply plate 11b has a plurality of holes for inserting the cell stacks 101. The number of holes provided corresponds to the number of cell stacks 101.

[0047] Like the upper power supply plate 11a, the lower power supply plate 11b supplies power by contacting the lead film 115 of the cell stack 101 with an elastic force generated by bending a part of the power supply plate.

[0048] One end of a conductive member 12b is joined to the lower power supply plate 11b. The other end of the conductive member 12b passes through the lower casing 229b and is connected to an electrode terminal (not shown) provided outside the cartridge 203.

[0049] In each cartridge 203, power is supplied to the electrolytic cell 105 of each cell stack 101 via an upper power supply plate 11a and a lower power supply plate 11b.

[0050] Fig. 5 shows a partial cross-sectional view of the power supply plate. The power supply plates (upper power supply plate 11a and lower power supply plate 11b) have a substrate 20 and a water vapor oxidation-resistant layer 21. The substrate 20 is a thin plate of stainless steel. Although not shown in Fig. 5, the substrate 20 has a plurality of holes formed therein into which the ends of the cell stack 101 corresponding to the holes in Fig. 3 are inserted.

[0051] The water vapor oxidation resistant layer 21 is provided so as to cover the surface of the substrate 20. The water vapor oxidation resistant layer 21 may cover both surfaces of the substrate 20. The water vapor oxidation resistant layer 21 is made of a material that has higher water vapor corrosion resistance than stainless steel, which is the material of the substrate 20. By covering the surface of the substrate 20 with the water vapor oxidation resistant layer 21, the water vapor oxidation resistance of the power supply plate at high temperatures can be ensured.

[0052] The material for the water vapor oxidation-resistant layer 21 may be nickel, titanium, or copper. Nickel has higher water vapor oxidation resistance and higher conductivity than stainless steel, thereby reducing the resistivity of the power feeder plate. However, nickel significantly reduces its strength at high temperatures and cannot be used alone for power feeder plates. However, by providing nickel as the water vapor oxidation-resistant layer 21 on the surface of the substrate 20, the power feeder plate's strength at high temperatures can be maintained while improving the power feeder plate's water vapor oxidation resistance. Titanium can prevent water vapor oxidation if it is several tens of micrometers thick. Although titanium is an expensive material, in this embodiment, simply applying titanium to the surface of the power feeder plate reduces costs compared to producing a power feeder plate using titanium alone.

[0053] The power supply plate may be configured by joining the base material 20 and the water vapor oxidation resistant layer 21 by cold welding or the like (clad steel).The power supply plate may also be configured by plating the water vapor oxidation resistant layer 21 on the surface of the base material 20.

[0054] As shown in FIG. 6 , the power feed plates (upper power feed plate 11 a and lower power feed plate 11 b) may have a conductive layer 22 between the substrate 20 and the water vapor oxidation-resistant layer 21. The conductive layer 22 is made of a material with higher conductivity than stainless steel, which is the material of the substrate 20. The material of the conductive layer 22 may be copper. Providing the conductive layer 22 reduces the electrical resistance of the power feed plate.

[0055] 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 plurality 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 plurality of cell stacks 101 via either or both of an upper seal member 237a and an adhesive member, and also isolates the steam supply header 217 from the oxidizing gas discharge header 223.

[0056] 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, 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 upper oxidizing gas penetrations 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.

[0057] The upper heat insulator 227a separates the steam electrolysis chamber 215 from the oxidizing gas discharge header 223, and prevents the atmosphere surrounding 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. 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 steam electrolysis chamber 215, a metal material with high temperature resistance, such as a Ni-based alloy, may be used. The upper heat insulator 227a guides the exhaust oxidizing gas, which has been exposed to high temperatures after passing through the steam electrolysis chamber 215, through the upper oxidizing gas penetration 235b and into the oxidizing gas discharge header 223.

[0058] According to this embodiment, the structure of the cartridge 203 described above allows the supply steam and the oxidizing gas to flow in opposite directions between the inside and outside of the cell stack 101. As a result, heat exchange occurs between the exhaust oxidizing gas and the steam supplied to the steam electrolysis chamber 215 through the interior of the base tube 103, and the exhaust oxidizing gas is cooled to a temperature that prevents damage due to stress to the upper tube plate 225a, etc., made of a metallic material, and is then supplied to the oxidizing gas discharge header 223. The supply steam is heated by heat exchange with the exhaust oxidizing gas discharged from the steam electrolysis chamber 215 and is then supplied to the steam electrolysis chamber 215. As a result, steam preheated to a temperature required for the electrolysis reaction can be supplied to the steam electrolysis chamber 215 without using a heater or the like.

[0059] The lower tube sheet 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 sheet 225b, the bottom plate of the lower casing 229b, and the lower insulator 227b are approximately parallel to each other. The lower tube sheet 225b has a plurality 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 sheet 225b airtightly supports the other ends of the plurality of cell stacks 101 via either or both of a lower seal member 237b and an adhesive member, and also isolates the produced hydrogen discharge header 219 from the oxidizing gas supply header 221.

[0060] 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 SOEC 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 lower oxidizing gas penetrations 235a formed between the inner surfaces of the holes and the outer surfaces of the cell stacks 101 inserted through the lower heat insulator 227b.

[0061] The lower heat insulator 227b separates the steam electrolysis chamber 215 from the oxidizing gas supply header 221, and prevents the atmosphere surrounding the lower tube sheet 225b from becoming too hot, thereby reducing its strength and increasing corrosion caused by the oxidizing agent contained in the oxidizing gas. 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 the high temperatures within the steam electrolysis chamber 215, a metal material with high temperature resistance, such as a Ni-based alloy, may be used. The lower heat insulator 227b guides the oxidizing gas supplied to the oxidizing gas supply header 221 through the lower oxidizing gas penetration 235a to the steam electrolysis chamber 215.

[0062] According to this embodiment, the structure of the cartridge 203 described above allows the product hydrogen and the oxidizing gas to flow in opposite directions between the inside and outside of the cell stack 101. As a result, the product hydrogen that passes through the interior of the base tube 103 and the steam electrolysis chamber 215 exchanges heat with the oxidizing gas supplied to the steam electrolysis chamber 215, and is cooled to a temperature that prevents damage due to stress to the lower tube plate 225b, which is made of a metal material, and is supplied to the product hydrogen discharge header 219. The oxidizing gas is heated by heat exchange with the product hydrogen and is supplied to the steam electrolysis chamber 215. As a result, the oxidizing gas heated to a temperature required for the electrolysis reaction can be supplied to the steam electrolysis chamber 215 without using a heater or the like.

[0063] 7 , the electrolysis cell module (hereinafter referred to as module) 201 includes, for example, a plurality of cartridges 203 and a module container 205 that houses the plurality of cartridges 203. The module 201 includes a water vapor supply header 207, a plurality of water vapor supply branch pipes 207a, a produced hydrogen discharge header 209, and a plurality of produced hydrogen discharge branch pipes 209a. The module 201 also includes an oxidizing gas supply header (not shown) and a plurality of oxidizing gas supply branch pipes (not shown).

[0064] The steam supply header 207 is provided inside the module container 205 and is connected to a steam supply unit that supplies steam at a predetermined gas composition and a predetermined flow rate corresponding to the amount of hydrogen generated by the module 201, and is also connected to multiple steam supply branch pipes 207a. This steam supply header 207 branches and guides the steam at a predetermined flow rate supplied from the steam supply unit to multiple steam supply branch pipes 207a. The steam supply branch pipes 207a are connected to the steam supply header 207 and are also connected to steam supply pipes 231a of the multiple cartridges 203. This steam supply branch pipe 207a guides the steam supplied from the steam supply header 207 to the multiple cartridges 203 at a substantially uniform flow rate, thereby substantially uniforming the electrolysis voltage of the multiple cartridges 203.

[0065] The produced hydrogen discharge branch pipe 209a is connected to the produced hydrogen discharge pipes 231b of the multiple cartridges 203 and is also connected to the produced hydrogen discharge mother pipe 209. This produced hydrogen discharge branch pipe 209a guides the produced hydrogen discharged from the cartridges 203 to the produced hydrogen discharge mother pipe 209. The produced hydrogen discharge mother pipe 209 is connected to the multiple produced hydrogen discharge branch pipes 209a and is partially disposed outside the module container 205. This produced hydrogen discharge mother pipe 209 guides the produced hydrogen discharged at a substantially uniform flow rate from the produced hydrogen discharge branch pipe 209a to the outside of the module container 205.

[0066] The module container 205 is operated with an internal pressure ranging from atmospheric pressure to several MPa and a surface temperature ranging from atmospheric temperature to approximately 300° C., and is preferably made of carbon steel, for example, from the viewpoint of cost reduction.

[0067] Here, in this embodiment, a configuration in which multiple cartridges 203 are grouped together and stored in a module container 205 is described, but this is not limited to this, and for example, a configuration in which the cartridges 203 are not grouped together but are stored in a module container 205 is also possible.

[0068] The DC power required for the electrolysis reaction is converted to a predetermined voltage by a power conversion device such as a power conditioner and then supplied to the module 201. The power supplied to the module 201 is distributed according to the number of cartridges connected in series and in parallel. In each cartridge 203, power is supplied via a power supply plate (upper power supply plate 11a and lower power supply plate 11b), and is 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 electrolysis cells 105, before being supplied to the electrolysis cells 105.

[0069] Second Embodiment A cartridge according to this embodiment differs from that of the first embodiment in the structure of the power feed plates (upper power feed plate and lower power feed plate), but the arrangement of the power feed plates is the same as that of the first embodiment.

[0070] 8 illustrates a partial cross-sectional view of a power feed plate according to this embodiment. The power feed plate 30 in this embodiment is a thin, plate-like substrate 32 having an emissivity-enhancing structure 31 on its surface. Similar to the substrate 20 in the first embodiment, the substrate 32 has a number of holes corresponding to the number of cell stacks 101. The substrate 32 is made of stainless steel.

[0071] The emissivity improving structure 31 is a structure that can improve the emissivity of the surface of the feeder plate. For example, the emissivity improving structure 31 may be an uneven structure formed on the surface of the substrate. The emissivity can be increased by increasing the surface roughness of the substrate 32. The uneven structure can be formed by shot blasting or sanding. For example, the emissivity improving structure 31 may be a heat dissipation paint applied to the surface of the substrate. The emissivity improving structure 31 of the feeder plate 30 shown in FIG. 8 is an uneven structure formed on the surface of the substrate.

[0072] The emissivity improving structure 31 may be applied to the power feeder plate of the first embodiment. In this case, for example, after the surface of the base material is covered with the water vapor oxidation resistant layer 21, irregularities are formed on the surface of the water vapor oxidation resistant layer 21, which will become the power feeder plate surface. This results in a power feeder plate equipped with an emissivity improving structure.

[0073] The effects of the feeder plate according to this embodiment will be described below. (Radiation Heat Transfer) The temperature of the feeder plate is determined by convection heat transfer with the surrounding gas and heat transfer to surrounding components by radiation heat transfer.

[0074] The amount of radiant heat Q transferred from the power supply plate to the heat-receiving object can be calculated using the Stefan-Boltzmann equation (3): Q = ε E Ｇ σA(T １ ４ -T ２ ４ ) (3) Q: Radiation heat transfer amount (W / m ２ ) ε: Emissivity E Ｇ : View factor σ: Stefan-Boltzmann coefficient (= 5.67032 × 10 －８ W / m ２ ・K ４ ) A: Sample surface area (m ２ ) T １ : Absolute temperature of the power supply plate (K) T ２ : Absolute temperature of the heat-receiving object (K)

[0075] Below, we compare convective heat transfer and radiative heat transfer using equation (3). １ is 500°C or higher, the ambient temperature around the power supply plate and the temperature of the heat-receiving object T ２ is 500℃ (constant), and the convection heat transfer coefficient is 5W / m ２ K, view factor E Ｇ It was assumed that the surface area A of the sample was 1. The atmospheric temperature inside the module container that houses the cartridge is about 400°C.

[0076] The results are shown in Figure 9. Figure 9 is a graph showing the relationship between the feeder plate temperature and the amount of heat transferred from the feeder plate. In Figure 9, the horizontal axis represents the feeder plate temperature (°C) and the vertical axis represents the amount of heat transferred from the feeder plate (kW / m ２ ), where the solid line represents convection heat transfer, the dashed line represents radiation heat transfer (emissivity 0.1), and the dashed line represents radiation heat transfer (emissivity 0.3).

[0077] The higher the feed plate temperature, the greater the amount of heat transferred from the feed plate. Figure 9 shows that, when compared at the same temperature, the higher the temperature, the greater the difference between the amount of heat transferred by convection and the amount of heat transferred by radiation. At a feed plate temperature of 600°C, radiation heat transfer was about three times that of convection. This shows that increasing the emissivity ε of the feed plate surface increases the amount of heat transferred by radiation, effectively suppressing the temperature rise of the feed plate.

[0078] Figure 10 shows an example of a trial calculation of the effect of increasing emissivity on reducing the temperature of the power feed plate. In this figure, the horizontal axis represents the emissivity of the power feed plate and the heat-receiving object, and the vertical axis represents the power feed plate temperature (°C).

[0079] According to FIG. 10, when the emissivity is increased from 0.1 to 0.3, a temperature reduction effect of about 100° C. can be expected.

[0080] 11 is a schematic diagram illustrating radiation heat transfer in the lower power feed plate 11b. The heat (RH) radiated from the lower power feed plate 11b is transferred to the lower tube sheet 225b and the produced hydrogen discharge header 219, and is then dissipated from the module to the outside by heat conduction and heat transfer.

[0081] However, the amount of heat from the power feed plate is originally small compared to the amount of heat dissipated to the outside of the module by heat transfer and heat conduction from the lower tube sheet 225b and the produced hydrogen discharge header 219. Therefore, by improving the emissivity of the power feed plate, the effects of temperature rises in the lower tube sheet 225b and the produced hydrogen discharge header 219 can be ignored.

[0082] The emissivity can be increased by performing a surface treatment on the feed plate and increasing the surface roughness.

[0083] (Surface Treatment and Emissivity) An element test was conducted to evaluate the effect of surface treatment on emissivity. A substrate (Ni-SUS304-Ni, Ni layer thickness 50 μm) with a Ni layer on both sides was surface treated to prepare a test specimen with an uneven structure, and the emissivity was measured with a radiometer. The surface treatment was performed by sanding or shot blasting. For comparison, the emissivity of a test specimen that had not been surface treated was also measured.

[0084] The results are shown in Figure 12. In this figure, the horizontal axis represents surface roughness Rz (μm) and the vertical axis represents emissivity ratio. The emissivity ratio is a ratio with the untreated material being 1.

[0085] According to FIG. 12, the test specimen having the uneven structure formed by the surface treatment has a higher emissivity than the untreated test specimen, and the emissivity ratio tends to increase as the surface roughness increases.

[0086] <Additional Notes> The electrolytic cell cartridge and the manufacturing method thereof described in the above-described embodiment can be understood, for example, as follows.

[0087] The electrolytic cell cartridge according to a first aspect of the present disclosure is an electrolytic cell cartridge comprising a plurality of electrolytic cell stacks (101) each having an electrolytic cell (105) and a power supply plate (11a, 11b) having holes for inserting the electrolytic cell stacks, into which the electrolytic cell stacks are inserted to electrically connect the plurality of electrolytic cell stacks, wherein the power supply plate comprises a stainless steel plate-shaped substrate (20) having holes for inserting the electrolytic cell stacks and a steam oxidation-resistant layer (21) covering the surface of the substrate, and the steam oxidation-resistant layer is made of a material having higher steam oxidation resistance than the substrate.

[0088] By providing a water vapor oxidation-resistant layer on the surface of the substrate, the power feeder plate can suppress water vapor oxidation corrosion caused by temperature rise when a high current is passed through it. Because the water vapor oxidation-resistant layer is used as part of the power feeder plate, cost increases can be kept to a minimum even if an expensive material is used for the water vapor oxidation-resistant layer. If a material with higher conductivity than stainless steel is used for the water vapor oxidation-resistant layer, the resistivity of the power feeder plate can be reduced, which is expected to suppress temperature rise and reduce resistance loss.

[0089] The electrolytic cell cartridge according to a second aspect of the present disclosure is the electrolytic cell cartridge of the first aspect, wherein the material of the water vapor oxidation resistant layer is selected from nickel, titanium, and copper.

[0090] Nickel, titanium, and copper all have higher steam oxidation resistance than stainless steel. Nickel and copper have higher electrical conductivity than stainless steel. Nickel cannot be used alone as a power supply plate because its strength decreases significantly at high temperatures. However, by providing nickel as a steam oxidation-resistant layer on the surface of the substrate, the power supply plate's steam oxidation resistance can be improved while maintaining its strength at high temperatures.

[0091] The electrolytic cell cartridge according to a third aspect of the present disclosure is the electrolytic cell cartridge of the first or second aspect described above, wherein the current supply plate has a conductive layer (22) made of a material having a higher conductivity than the substrate between the substrate and the steam oxidation-resistant layer.

[0092] By providing the conductive layer, the conductivity of the feed plate can be reliably reduced.

[0093] An electrolytic cell cartridge according to a fourth aspect of the present disclosure comprises a plurality of electrolytic cell stacks each having an electrolytic cell, and a power supply plate that electrically connects the plurality of electrolytic cell stacks in parallel, the power supply plate having a stainless steel plate-shaped substrate with a hole for inserting the electrolytic cell stack, and an emissivity enhancing structure (31) on the surface for improving the emissivity of the power supply plate.

[0094] By providing an emissivity-enhancing structure, the emissivity of the feeder plate can be increased, which increases the amount of heat transferred by radiation from the surface of the feeder plate, making it possible to reduce the temperature of the feeder plate to an acceptable level even when a high current is passing through it.

[0095] The electrolytic cell cartridge according to a fifth aspect of the present disclosure is the fourth aspect, wherein the emissivity improving structure is an irregularity provided on the surface of the power supply plate.

[0096] By providing irregularities to increase the surface roughness of the feeder plate, the emissivity of the feeder plate increases.

[0097] A method for manufacturing an electrolytic cell cartridge according to a sixth aspect of the present disclosure is a method for manufacturing a cartridge comprising a plurality of electrolytic cell stacks each having an electrolytic cell and a power supply plate electrically connecting the plurality of electrolytic cell stacks, the power supply plate having a stainless steel plate-shaped substrate having a hole for inserting the electrolytic cell stack, and the surface roughness of the power supply plate is increased by shot blasting or sanding.

[0098] DESCRIPTION OF SYMBOLS 11a, 11b, 30 Power supply plate 12a, 12b Conductive member 13 Elastic force generating portion 20, 32 Substrate 21 Steam oxidation resistant layer 22 Conductive layer 31 Emissivity improving structure 101 Cell stack (electrolysis cell stack) 103 Base tube 105 Electrolysis cell 107 Interconnector 109 Hydrogen electrode (fuel electrode) 111 Solid electrolyte membrane 113 Oxygen electrode 115 Lead film 201 Module (electrolysis cell module) 203 Cartridge (electrolysis cell cartridge) 205 Module container 207 Steam supply header 207a Steam supply branch pipe 209 Produced hydrogen discharge header 209a Produced hydrogen discharge branch pipe 215 Steam electrolysis chamber 217 Steam supply header 219 Produced hydrogen discharge header 221 Oxidizing gas supply header 223 Oxidizing gas discharge header 225a Upper tube plate 225b Lower tube plate 227a Upper heat insulator 227b Lower heat insulator 229a Upper casing 229b Lower casing 231a Steam supply pipe 231b Produced hydrogen discharge pipe 233a Oxidizing gas supply pipe 233b Oxidizing gas discharge pipe 235a Oxidizing gas lower penetration part 235b Oxidizing gas upper penetration part 237a Upper seal member 237b Lower seal member 620 Temperature measurement part

Claims

1. An electrolytic cell cartridge comprising: a plurality of electrolytic cell stacks each having an electrolytic cell for electrolyzing water vapor; and a power supply plate having holes for inserting the electrolytic cell stacks into which the electrolytic cell stacks are inserted to electrically connect the plurality of electrolytic cell stacks, wherein the power supply plate comprises a stainless steel plate-shaped substrate having holes for inserting the electrolytic cell stacks, and a water vapor oxidation resistant layer covering the surface of the substrate, and the water vapor oxidation resistant layer is made of a material that has higher water vapor oxidation resistance than the substrate.

2. The electrolytic cell cartridge of claim 1, wherein the material of said water vapor oxidation resistant layer is selected from nickel, titanium and copper.

3. The electrolytic cell cartridge according to claim 1, wherein the current supply plate has a conductive layer between the substrate and the steam oxidation resistant layer, the conductive layer being made of a material having a higher conductivity than the substrate.

4. An electrolytic cell cartridge comprising a plurality of electrolytic cell stacks each having an electrolytic cell for electrolyzing water vapor, and a power supply plate electrically connecting the plurality of electrolytic cell stacks, wherein the power supply plate has a stainless steel plate-shaped substrate having a hole for inserting the electrolytic cell stack, and an emissivity enhancing structure on the surface for improving the emissivity of the power supply plate.

5. The electrolytic cell cartridge according to claim 4, wherein the emissivity improving structure is an uneven surface provided on the surface of the current feeder plate.

6. A method for manufacturing an electrolytic cell cartridge comprising a plurality of electrolytic cell stacks each having an electrolytic cell for electrolyzing water vapor, and a power supply plate for electrically connecting the plurality of electrolytic cell stacks in parallel, the power supply plate having a stainless steel plate-shaped substrate with holes for inserting the electrolytic cell stacks, the method comprising increasing the surface roughness of the power supply plate by blasting or sanding.

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