Electrolytic cell cartridge and method of manufacturing same

Abstract

The present disclosure aims to suppress steam oxidation of power supply members in an electrolytic cell cartridge. [Solution] The electrolytic cell cartridge 203 of the present disclosure is an electrolytic cell cartridge comprising a plurality of electrolytic cell stacks 101 each having an electrolytic cell 105, and power supply plates 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 plate-shaped stainless steel substrate having a hole 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 having higher water vapor oxidation resistance than the substrate.

Description

[Technical field]

[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 water vapor, and a manufacturing method thereof. [Background technology]

[0002] In recent years, in order to achieve carbon neutrality, there has been a demand for the development of inexpensive, large-capacity hydrogen production systems that do not emit CO2.

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

[0004] Among these, solid oxide electrolysis cells (SOECs, hereafter referred to as "electrolysis cells") that electrolyze high-temperature steam use ceramics with oxygen ion conductivity, such as yttria-stabilized zirconia, as the 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. In addition, it is also possible to perform co-electrolysis, in which a mixture of high-temperature steam and carbon dioxide (CO2) is supplied, 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 electrochemical cells are being developed as reversible solid oxide electrochemical cells (RSOC) (hereinafter referred to as "reversible cells") that have the two-way function of producing hydrogen and oxygen through a reverse reaction by supplying electric power and high-temperature steam from the outside, and generating electricity as a fuel cell.

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

[0007] Since the electrolytic reaction of an SOEC is an endothermic reaction, it is possible to apply a higher current to the SOEC than to a solid oxide fuel cell (SOFC) for generating electricity as described in Patent Document 2. For cells with the same specifications, a current several times higher than that of the SOFC can be applied to the SOEC. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 7282968 [Patent Document 2] Patent No. 5106884 Summary of the Invention [Problem to be solved by the invention]

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

[0010] However, in SOECs, which carry higher currents than SOFCs, self-heating due to the resistance of the power supply components increases in proportion to the square of the current value when current flows horizontally through the power supply components, resulting in a larger temperature rise. This can cause problems with the current collecting materials used in SOFCs, as the temperature of the power supply components rises to an unacceptable level (over 650°C) from the standpoint of corrosion and thermal stress. This places a constraint on fully utilizing the performance of the cell stack, and so measures are required.

[0011] Furthermore, the power supply components of an SOEC are exposed to an atmosphere containing high concentrations of water vapor, which is the raw material for electrolysis. As a result, when temperatures reach a certain level (for example, above about 500°C for a SUS304 power supply plate), water vapor oxidation accelerates. As water vapor oxidation progresses, oxide scale forms on the power supply components and they become thinner. The formation of oxide scale causes an increase in resistance at the joints with the cell stack. Thinning reduces the cross-sectional area of ​​the power supply components (thin plates), which increases resistance and leads to a further rise in temperature.

[0012] The present disclosure has been made in consideration of the above circumstances, In order to solve the problem of thinning of power supply components due to steam oxidation, An object of the present invention is to provide an electrolytic cell cartridge capable of suppressing steam oxidation of a power supply member.

[0013] The present disclosure also provides In order to solve the problem of thinning of power supply components due to steam oxidation, An object of the present invention is to provide an electrolytic cell cartridge capable of suppressing a temperature rise caused by steam oxidation of a power supply member within an allowable level. [Means for solving the problem]

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

[0015] The invention according to the present disclosure is Electrolyze water vapor Provided is an electrolytic cell cartridge comprising a plurality of electrolytic cell stacks each having an electrolytic cell, 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 a hole for inserting the electrolytic cell stacks, and a water vapor oxidation resistant layer covering a surface of the substrate, and the water vapor oxidation resistant layer is made of a material having higher water vapor oxidation resistance than the substrate.

[0016] By providing a water vapor oxidation resistant layer on the surface of the substrate, the feeder plate can suppress water vapor oxidation corrosion caused by temperature rise due to self-heating of the feeder plate when a high current is passed through it. Since the water vapor oxidation resistant layer is used as part of the feeder plate, the increase in cost can be kept to a minimum even if an expensive material is used for the water vapor oxidation resistant layer. If a material with a higher conductivity than stainless steel is used for the water vapor oxidation resistant layer, it is possible to suppress temperature rise and reduce resistance loss by lowering the resistivity of the feeder plate.

[0017] The invention according to the present disclosure is Electrolyze water vapor An electrolytic cell cartridge is provided, 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 base material 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.

[0018] By providing a structure that improves emissivity, it is possible to increase the emissivity of the feed plate. This increases the amount of heat transferred (heat dissipation) by radiation from the feed plate surface, making it possible to suppress the temperature of the feed plate to an acceptable level even when a high current is passing through it.

[0019] In addition, the present disclosure relates to Electrolyze water vapor The present invention provides a method for manufacturing an electrolytic cell cartridge, comprising 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 plate-shaped substrate made of stainless steel having a hole for inserting the electrolytic cell stack, the method increasing the surface roughness of the power supply plate by shot blasting or sanding. Effect of the Invention

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

[0021] In addition, the present disclosure provides an electrolytic cell cartridge that can suppress the temperature rise of the power supply member to within an acceptable level by providing an emissivity improving structure on the surface of the power supply plate. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 illustrates an embodiment of a cylindrical electrolysis cell stack according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 illustrates an embodiment of a cylindrical electrolysis cell stack according to an embodiment of the present disclosure. [Diagram 3] FIG. 3 is a top view of the periphery of the cell stack in FIG. 2. [Figure 4] 4 is a schematic diagram illustrating the relationship between an upper power supply plate and a cell stack. FIG. [Diagram 5] FIG. 2 is a partial cross-sectional view of the feed plate according to the first embodiment. [Figure 6] FIG. 4 is a partial cross-sectional view of another feed plate according to the first embodiment. [Figure 7] FIG. 1 illustrates an embodiment of a cylindrical electrolytic cell cartridge according to an embodiment of the present disclosure. [Figure 8] FIG. 11 is a diagram showing a partial cross-sectional view of a feed plate according to a second embodiment. [Figure 9] 13 is a graph showing the relationship between the temperature of a power feed plate and the amount of heat transfer from the power feed plate. [Figure 10] FIG. 13 is a diagram showing an example of a trial calculation of the effect of reducing the temperature of a power supply plate due to an increase in emissivity. [Figure 11] 5 is a schematic diagram illustrating radiative heat transfer in the lower power supply plate. FIG. [Figure 12] FIG. 13 is a diagram showing the relationship between the surface roughness Rz and the emissivity increase rate of each test specimen. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of an electrolytic cell cartridge and a manufacturing method thereof 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 paper surface indicates the vertically upper side and vertically lower side, respectively. Also, in this embodiment, for components that can obtain the same effect in the vertical direction and the horizontal direction, the vertical direction on the paper surface is not necessarily limited to the vertical direction, but may correspond to, for example, a 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 according to the present embodiment. When a substrate tube is not used, for example, a fuel electrode may be formed thick to serve as the substrate tube, and the use of the substrate tube is not limited. In addition, the substrate tube in the present embodiment will be described as having a cylindrical shape, but the substrate tube may be cylindrical and the cross section 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 surface of a cylinder is crushed vertically may also be used. Here, FIG. 1 shows one mode of a cell stack according to the embodiment. The cell stack 101 includes, for example, a cylindrical substrate tube 103, a plurality of electrolysis cells 105 formed on the outer peripheral surface of the substrate tube 103, and an interconnector 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 also 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 base tube 103 among the multiple electrolytic cells 105 formed on the outer peripheral surface of the base 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 base tube 103 is made of a porous material, and is mainly composed of, for example, CaO-stabilized ZrO2 (CSZ), a mixture of CSZ and nickel oxide (NiO) (CSZ+NiO), Y2O3-stabilized ZrO2 (YSZ), MgAl2O4, etc. This base tube 103 supports the electrolytic cell 105, the interconnector 107, and the lead film 115, and diffuses the supply steam 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, for example, Ni / YSZ. 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 airtightness that makes it difficult for gas to pass through and high oxygen ion conductivity at high temperatures. The solid electrolyte membrane 111 is a membrane that 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, a LaSrMnO3-based oxide or a LaCoO3-based oxide, and the oxygen electrode 113 is formed by screen printing or applying a slurry 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 that exhibits high ionic conductivity, and the oxygen electrode layer (oxygen electrode conductive layer) on the oxygen electrode intermediate layer may be made of a perovskite oxide such as Sr- and Ca-doped LaMnO3.

[0030] The gas supplied to and discharged from the hydrogen electrode 109 often contains hydrogen in addition to the water vapor used in electrolysis; however, in the following explanation, to avoid confusion, the supply gas containing hydrogen will be called "supplied water vapor" and the hydrogen gas containing water vapor discharged from the hydrogen electrode 109 will be called "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 produce hydrogen molecules and oxygen ions (O 2- ) is produced (see reaction formula (1) below). The produced hydrogen is taken out 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. H2O+2e - →H2+O 2- (1) 2O 2- →O2+4e - (2)

[0033] The oxidizing gas is not directly involved in the electrolytic reaction, but supplies heat necessary for the electrolytic reaction (endothermic) and expels excess heat generated by the electrolytic reaction. It is usually a gas containing approximately 15% to 30% oxygen, and air is a typical example, but other than air, a mixed gas of combustion exhaust gas and air, a mixed gas of oxygen and air, an inert gas such as nitrogen, etc. can also be used.

[0034] 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) or lanthanum chromite (LaCrO3) and is screen-printed as a slurry. The interconnector 107 is a dense film so that the supplied water vapor and the oxidizing gas do not mix. The interconnector 107 also 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 in adjacent electrolytic cells 105, thereby connecting the adjacent electrolytic cells 105 in series.

[0035] 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. For this reason, a composite material of Ni and a zirconia-based electrolyte material, such as Ni / YSZ, or a M material such as SrTiO3 is used. 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 applies DC power required for the electrolytic reaction to the end of the cell stack 101, which is connected in series by the interconnector 107. In addition, the surface on the oxidizing gas side may be protected with an airtight oxidation-resistant material so that metal materials such as Ni are not oxidized.

[0036] (Electrolytic cell cartridge) 2, the electrolysis cell cartridge (hereinafter, cartridge) 203 includes a plurality of cell stacks 101, a water vapor electrolysis chamber 215, a water vapor 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 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 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 water vapor electrolysis chamber 215 is an area formed between the upper insulator 227a and the lower insulator 227b. This water vapor electrolysis chamber 215 is an area in which the electrolysis cells 105 of the cell stack 101 are arranged, and is an area in which water vapor is electrolyzed to produce hydrogen. The temperature near the center of the cell stack 101 in the longitudinal direction of the water vapor electrolysis chamber 215 may be monitored by a temperature measurement unit 620 (such as a temperature sensor or a thermocouple), and during steady operation of the module 201 described below, a high-temperature atmosphere of approximately 700°C to 1000°C is produced.

[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 on the upper part 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 base tubes 103 of the multiple cell stacks 101 at a substantially uniform flow rate, thereby making the hydrogen generation performance of the multiple cell stacks 101 substantially uniform.

[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] The oxidizing gas supply main pipe (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 multiple cartridges 203. The oxidizing gas supply header 221 is an area surrounded by the lower casing 229b, the lower tube plate 225b, and the 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 a predetermined flow rate of oxidizing gas supplied from the oxidizing gas supply branch pipe (not shown) through the oxidizing gas supply pipe 233a to the steam electrolysis chamber 215 through an oxidizing gas lower penetration part 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 through an oxidizing gas upper through-hole 235b (described later) to the oxidizing gas discharge branch pipe (not shown) via the oxidizing gas discharge pipe 233b.

[0042] The power supply plates are disposed on the upper and lower end sides of the cell stacks 101, respectively, and electrically connect the multiple cell stacks 101 in parallel.

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

[0044] Fig. 3 shows a top view of the cell stack and its periphery in Fig. 2. Fig. 4 shows a schematic diagram explaining the relationship between the upper power supply plate and the cell stack. Power is supplied by contacting the lead film 115 of the cell stack 101 with an elastic force (elastic force generating part 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 within 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 the holes corresponds to the number of the cell stacks 101.

[0047] Like the upper feeder plate 11a, the lower feeder plate 11b feeds power by contacting the lead film 115 of the cell stack 101 with an elastic force generated by bending a part of the feeder 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 cells 105 of each cell stack 101 via an upper power supply plate 11a and a lower power supply plate 11b.

[0050] A partial cross-sectional view of the power supply plate is shown in Fig. 5. 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 sides of the substrate 20. The water vapor oxidation resistant layer 21 is made of a material that is more resistant to water vapor corrosion 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 of the water vapor oxidation resistant layer 21 may be nickel, titanium or copper. Nickel has higher steam oxidation resistance than stainless steel and also has high electrical conductivity, which reduces the resistivity of the current feeder plate. However, nickel cannot be used alone as a current feeder plate because its strength decreases significantly at high temperatures. However, by providing nickel on the surface of the substrate 20 as the steam oxidation resistant layer 21, the strength of the current feeder plate at high temperatures can be ensured while increasing the steam oxidation resistance of the current feeder plate. Titanium can prevent steam oxidation if it has a thickness of several tens of μm. Titanium is a material with a high unit price, but in this embodiment, it is sufficient to apply titanium to the surface of the current feeder plate, so the cost can be reduced compared to producing the current feeder plate using titanium alone.

[0053] The power supply plate may be configured by bonding 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 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 11a and lower power feed plate 11b) 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 having a higher conductivity than stainless steel, which is the material of the substrate 20. The material of the conductive layer 22 may be copper. By providing the conductive layer 22, the electrical resistance of the power feed plate is reduced.

[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 heat insulator 227a so that the upper tube plate 225a, the top plate of the upper casing 229a, and the upper heat 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 the upper seal member 237a and the adhesive member, and isolates the water vapor 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 to each other, and is fixed to the side plate of the upper casing 229a. The upper heat insulator 227a is provided with a plurality of holes corresponding to the number of cell stacks 101 provided in the cartridge 203. The diameter of the holes is set to be larger than the outer diameter of the cell stacks 101. The upper heat insulator 227a is provided with an upper oxidizing gas penetration part 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.

[0057] The upper heat insulator 227a separates the steam electrolysis chamber 215 from the oxidizing gas discharge header 223, and prevents the atmosphere around the upper tube sheet 225a from becoming hot, resulting in a decrease in strength and an increase in corrosion caused by the oxidizing agent contained in the oxidizing gas. In addition, a metal material having high temperature resistance, such as a Ni-based alloy, may be used to prevent the upper tube sheet 225a and the like from being thermally deformed due to a temperature difference caused by exposure to the high temperature in the steam electrolysis chamber 215. The upper heat insulator 227a guides the exhaust oxidizing gas, which has passed through the steam electrolysis chamber 215 and been exposed to high temperatures, to the oxidizing gas discharge header 223 by passing it through the upper oxidizing gas penetration part 235b.

[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, the exhaust oxidizing gas exchanges heat with the steam supplied to the steam electrolysis chamber 215 through the inside of the base tube 103, and is cooled to a temperature at which the upper tube plate 225a and other components made of a metal material are prevented from being damaged by stress, 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, it is possible to supply the steam preheated to a temperature required for the electrolysis reaction to the steam electrolysis chamber 215 without using a heater or the like.

[0059] 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 the lower seal member 237b and the adhesive member, and separates 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 is provided with a plurality of holes corresponding to the number of cell stacks 101 provided in the SOEC cartridge 203. The diameter of the holes is set to be larger than the outer diameter of the cell stacks 101. The lower heat insulator 227b is provided with a lower oxidizing gas penetration portion 235a formed between the inner surface of the hole and the outer surface of the cell stack 101 inserted into the lower heat insulator 227b.

[0061] The lower insulator 227b separates the steam electrolysis chamber 215 from the oxidizing gas supply header 221, and prevents the atmosphere around the lower tube sheet 225b from becoming hot, resulting in a decrease in strength and an increase in corrosion caused by the oxidizing agent contained in the oxidizing gas. In addition, a metal material having high temperature resistance, such as a Ni-based alloy, may be used to prevent the lower tube sheet 225b and the like from being thermally deformed due to a temperature difference caused by exposure to the high temperature in the steam electrolysis chamber 215. The lower insulator 227b guides the oxidizing gas supplied to the oxidizing gas supply header 221 to the steam electrolysis chamber 215 by passing it through the oxidizing gas lower penetration 235a.

[0062] According to this embodiment, the structure of the cartridge 203 described above allows the produced hydrogen and the oxidizing gas to flow in opposite directions between the inside and outside of the cell stack 101. As a result, the produced hydrogen that has passed through the inside 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 at which the lower tube plate 225b made of a metal material and other components can be prevented from being damaged by stress, and is then supplied to the produced hydrogen discharge header 219. The oxidizing gas is heated by heat exchange with the produced hydrogen, and is then 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] (Electrolysis cell module) 7, the electrolysis cell module (hereinafter, abbreviated 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 main pipe 207, a plurality of water vapor supply branch pipes 207a, a produced hydrogen discharge main pipe 209, and a plurality of produced hydrogen discharge branch pipes 209a. The module 201 also includes an oxidizing gas supply main pipe (not shown) and a plurality of oxidizing gas supply branch pipes (not shown).

[0064] The water vapor supply mother pipe 207 is provided inside the module container 205, and is connected to a water vapor supply unit that supplies water vapor with 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 water vapor supply branch pipes 207a. This water vapor supply mother pipe 207 branches and guides water vapor at a predetermined flow rate supplied from the above-mentioned water vapor supply unit to multiple water vapor supply branch pipes 207a. In addition, the water vapor supply branch pipe 207a is connected to the water vapor supply mother pipe 207, and is also connected to water vapor supply pipes 231a of the multiple cartridges 203. This water vapor supply branch pipe 207a guides water vapor supplied from the water vapor supply mother pipe 207 to the multiple cartridges 203 at an approximately uniform flow rate, and approximately uniforms 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. In addition, the produced hydrogen discharge mother pipe 209 is connected to the multiple produced hydrogen discharge branch pipes 209a, and a portion of the produced hydrogen discharge mother pipe 209 is 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 of atmospheric pressure to several MPa and a surface temperature of atmospheric temperature to approximately 300° C., and is preferably made of, for example, carbon steel from the viewpoint of reducing costs.

[0067] Here, in this embodiment, a configuration in which multiple cartridges 203 are grouped together and stored in a module container 205 is described; however, this is not limited to this, and for example, the cartridges 203 may be stored in the module container 205 without being grouped together.

[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 supplied to the module 201. The power supplied to the module 201 is fed according to the number of cartridges in series and the number of cartridges in parallel. In each cartridge 203, power is fed via a power feed plate (upper power feed plate 11a and lower power feed plate 11b) and is passed 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 multiple electrolysis cells 105, and then supplied to the electrolysis cells 105.

[0069] Second Embodiment The cartridge according to this embodiment differs from 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 in the first embodiment.

[0070] FIG. 8 illustrates a partial cross-sectional view of the feed plate according to the present embodiment. The power supply plate 30 in this embodiment is a thin plate-like substrate 32 having an emissivity improving 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 feed 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 substrate surface. The emissivity improving structure 31 of the power supply plate 30 shown in FIG. 8 is an uneven structure formed on the substrate surface.

[0072] The emissivity improving structure 31 may be applied to the power feeder plate of the first embodiment. In that case, for example, after the surface of the base material is covered with the water vapor oxidation resistant layer 21, the surface of the water vapor oxidation resistant layer 21 that becomes the power feeder plate surface is formed with unevenness. This can result 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 feed plate is determined by heat transfer through convection with the surrounding gas and through radiation to the surrounding components.

[0074] The amount of radiative heat transfer Q from the current feed plate to the heat-receiving object can be calculated using the Stefan-Boltzmann equation (3). Q = ε E G σA(T1 4 -T2 4 ) · · · (3) Q: Radiation heat transfer rate (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 ) T1: Absolute temperature of the power supply plate (K) T2: Absolute temperature of the heat receiving object (K)

[0075] A comparison of convective heat transfer and radiative heat transfer was made using the following formula (3). The maximum temperature T1 of the current feed plate is 500°C or higher, the ambient temperature around the current collector plate and the temperature T2 of the heat receiving object are 500°C (constant), and the convective heat transfer coefficient is 5W / m 2 K, view factor E G is assumed to be 1, and the sample surface area A is assumed to be 1. The atmospheric temperature in 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 current feed plate temperature and the amount of heat transfer from the current feed plate. In Figure 9, the horizontal axis shows the current feed plate temperature (°C) and the vertical axis shows the amount of heat transfer from the current feed plate (kW / m 2 ), the solid line is convection heat transfer, the dashed line is radiation heat transfer (emissivity 0.1), and the dashed line is radiation heat transfer (emissivity 0.3).

[0077] The higher the feed plate temperature, the greater the amount of heat transfer from the feed plate. According to Figure 9, when comparing at the same temperature, the higher the temperature, the greater the difference between the amount of heat transfer by convection and that by radiation, and when the feed plate temperature reached 600°C, radiation heat transfer was about three times that of convection. This shows that by increasing the emissivity ε of the feed plate surface, the amount of heat transfer by radiation can be increased, effectively suppressing the temperature rise of the feed plate.

[0078] An example of a calculation of the effect of reducing the temperature of the feed plate due to an increase in emissivity is shown in Figure 10. In this figure, the horizontal axis is the emissivity of the feed plate and the heat-receiving object, and the vertical axis is the feed plate temperature (℃).

[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 moves to the lower tube sheet 225b and the produced hydrogen discharge header 219, and is further dissipated from the module to the outside by thermal 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 thermal 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 rise of 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) Elemental tests were carried out to evaluate the effect of surface treatment on emissivity. A surface treatment was performed on a substrate (Ni-SUS304-Ni, Ni layer thickness 50μm) with Ni layers on both sides, a test specimen with an uneven structure was produced, 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 is surface roughness Rz (μm) and the vertical axis is emissivity ratio. The emissivity ratio is a ratio assuming that the untreated material is 1.

[0085] According to FIG. 12, compared to the untreated test specimen, the test specimen with the uneven structure formed by surface treatment had a higher emissivity, and a tendency was shown in which the emissivity ratio also increased as the surface roughness increased.

[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) having electrolytic cells (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 water steam oxidation resistant layer (21) covering the surface of the substrate, and the water steam oxidation resistant layer is made of a material having higher water steam oxidation resistance than the substrate.

[0088] By providing a water vapor oxidation resistant layer on the surface of the substrate, the 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 feeder plate, the increase in cost 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, it is possible to suppress temperature rise and reduce resistance loss by lowering the resistivity of the feeder plate.

[0089] The electrolytic cell cartridge according to a second aspect of the present disclosure is the electrolytic cell cartridge according to 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 are all more resistant to steam oxidation than stainless steel. Nickel and copper are more conductive than stainless steel. However, 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 steam oxidation resistance of the power supply plate can be increased 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 according to the first or second aspect described above, wherein the power supply plate has a conductive layer (22) between the substrate and the water vapor oxidation resistant layer, the conductive layer being made of a material having a higher conductivity than the substrate.

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

[0093] The electrolytic cell cartridge according to a fourth aspect of the present disclosure comprises a plurality of electrolytic cell stacks having electrolytic cells, 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 having 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 a structure for improving emissivity, it is possible to increase the emissivity of the feed plate, which in turn increases the amount of heat transferred by radiation from the surface of the feed plate, making it possible to reduce the temperature of the feed 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 electrolytic cell cartridge of the fourth aspect, wherein the emissivity improving structure is an unevenness provided on the surface of the power supply plate.

[0096] By increasing the surface roughness of the feed plate by providing it with projections and recesses, the emissivity of the feed plate is increased.

[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 having electrolytic cells and a power supply plate electrically connecting the plurality of electrolytic cell stacks, the power supply plate having a plate-shaped substrate made of stainless steel having a hole for inserting the electrolytic cell stack, and increasing the surface roughness of the power supply plate by shot blasting or sanding. [Explanation of symbols]

[0098] 11a,11b,30 Power supply board 12a, 12b Conductive member 13 Elastic force generating section 20,32 Base material 21 Water vapor oxidation resistant layer 22 Conductive layer 31 Emissivity improvement 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 pole 115 Lead Film 201 Module (Electrolysis Cell Module) 203 Cartridge (Electrolytic Cell Cartridge) 205 Module Container 207 Steam supply header 207a Steam supply branch 209 Hydrogen production discharge header 209a Hydrogen production discharge branch 215 Steam electrolysis chamber 217 Steam Supply Header 219 Produced hydrogen discharge header 221 Oxidizing gas supply header 223 Oxidizing gas exhaust header 225a Upper tube plate 225b Lower tube sheet 227a Upper insulation 227b Lower insulation 229a Upper casing 229b Lower casing 231a Steam supply pipe 231b Hydrogen production discharge pipe 233a Oxidizing gas supply pipe 233b Oxidizing gas exhaust pipe 235a Oxidizing gas lower penetration 235b Oxidizing gas upper penetration 237a Upper seal member 237b Lower seal member 620 Temperature measurement section

Claims

1. A method for electrolyzing water vapor comprising: a power supply plate having a hole for inserting the electrolytic cell stack, the electrolytic cell stack being inserted into the hole to electrically connect a plurality of the electrolytic cell stacks, the current supply plate comprises a stainless steel plate-shaped substrate having a hole for inserting the electrolysis cell stack, and a water vapor oxidation resistant layer covering a surface of the substrate; The water vapor oxidation resistant layer is made of a material having higher water vapor oxidation resistance than the base material.

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

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

4. A power generating apparatus 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; An electrolytic cell cartridge in which 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. 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 supply plate.

6. A method for manufacturing a 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 plate-shaped substrate made of stainless steel having a hole for inserting the electrolytic cell stack, comprising: A method for manufacturing an electrolytic cell cartridge, comprising the steps of: increasing the surface roughness of the current feed plate by blasting or sanding;

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