Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
  • H01M8/028—Sealing means characterised by their material
  • H01M8/0282—Inorganic material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0297—Arrangements for joining electrodes, reservoir layers, heat exchange units or bipolar separators to each other
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
  • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
  • H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
  • H01M8/2425—High-temperature cells with solid electrolytes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
  • H01M2008/1293—Fuel cells with solid oxide electrolytes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells

Definitions

• the invention relates to a gasket for a solid oxide cell (SOC) stack system, in particular a solid oxide fuel cell (SOFC) stack system or a solid oxide electrolysis cell (SOEC) stack system.
• SOC solid oxide cell
• SOFC solid oxide fuel cell
• SOEC solid oxide electrolysis cell
• a Solid Oxide Fuel Cell comprises a solid electro ⁇ lyte that enables the conduction of oxygen ions, a cathode where oxygen is reduced to oxygen ions and an anode where hydrogen is oxidised.
• the overall reaction in a SOFC is that hydrogen and oxygen electrochemically react to produce electricity, heat and water.
• the anode normally possesses catalytic ac ⁇ tivity for the steam reforming of hydrocarbons, particular- ly natural gas, whereby hydrogen, carbon dioxide and carbon monoxide are generated.
• Steam reforming of methane, the main component of natural gas can be described by the fol ⁇ lowing equations:
• an oxidant such as air is supplied to the solid oxide fuel cell in the cathode region.
• Fuel such as hydrogen is supplied in the anode region of the fuel cell.
• a hydrocarbon fuel such as methane is sup ⁇ plied in the anode region, where it is converted to hydro ⁇ gen and carbon oxides by the above reactions.
• Hydrogen passes through the porous anode and reacts at the anode/- electrolyte interface with oxygen ions generated on the cathode side that have diffused through the electrolyte.
• Oxygen ions are created in the cathode side with an input of electrons from the external electrical circuit of the cell .
• ⁇ terconnects serve as a gas barrier to separate the anode (fuel) and cathode (air/oxygen) sides of adjacent cell units, and at the same time they enable current conduction between the adjacent cells, i.e. between an anode of one cell with a surplus of electrons and a cathode of a neigh ⁇ bouring cell needing electrons for the reduction process.
• interconnects are normally provided with a plural ⁇ ity of flow paths for the passage of fuel gas on one side of the interconnect and oxidant gas on the opposite side.
• a range of positive values should be maximized without unacceptable consequence on another range of related negative values which should be minimized.
• the flow paths on the fuel side of the interconnect should be designed to seek an equal amount of fuel to each cell in a stack, i.e. there should be no flow- "short-cuts" through the fuel side of the stack.
• Design of the process gas flow paths in the SOFC stack and its fuel cell units should seek to achieve a low pressure loss per flow volume at least on the air side and poten ⁇ tially on the fuel side of the interconnect, which will re ⁇ cute the parasitic loss to blowers.
• the interconnect leads current between the anode and the cathode layer of neighbouring cells.
• the electrically conducting contact points hereafter merely called "contact points" of the interconnect should be designed to establish good electri ⁇ cally contact to the electrodes (anode and cathode) and the contact points should no where be far apart, which would force the current to run through a longer distance of the electrode with resulting higher internal resistance.
• the interconnects price contribution can be reduced by not using noble materials, by reducing the production time of the interconnect and minimizing the material loss.
• the temperature should be high enough to ensure catalytic reaction in the cell, yet low enough to avoid accelerated degradation of the cell components.
• the interconnect should therefore contribute to an even temperature distribution giving a high average temperature without exceeding the maximum temperature.
• Production time of the interconnect itself should be mini ⁇ mized and the interconnect design should also contribute to a fast assembling of the entire stack. In general, for eve ⁇ ry component the interconnect design renders unnecessary, there is a gain in production time.
• the interconnect production methods and materials should permit a low interconnect fail rate (such as unwanted holes in the interconnect gas barrier, uneven material thickness or characteristics) . Further the fail-rate of the assembled cell stack can be reduced when the interconnect design re ⁇ Jerusalem the total number of components to be assembled and reduces the length of seal surfaces. Number of components.
• the way the anode and cathode gas flows are distributed in an SOFC stack is by having a common manifold for each of the two process gasses.
• the manifolds can either be inter- nal or external.
• the manifolds supply process gasses to the individual layers in the SOFC stack by the means of chan ⁇ nels to each layer.
• the channels are normally situated in one layer of the repeating elements which are comprised in the SOFC stack, i.e. in the spacers or in the interconnect.
• connections to the stack are necessary. It is at least necessary to have process gas connections and electrical connections. Manifolds and pip ⁇ ing are used to connect a stack with process gas. In some embodiments, it is necessary to apply gaskets between the manifolds and piping, and the SOC stack.
• the gaskets need to be able to withstand multiple thermal cycles and still be leak proof. It is a requirement to the SOC stacks that they can be electrically connected in series and that they are electrically floating, i.e. none of the stacks are electrically grounded. Therefore the gaskets need also to be electrically insulating.
• US2005266288 discloses a solid oxide fuel cell generator that contains stacks of hollow axially elongated fuel cells having an open top end, an oxidant inlet plenum, a feed fuel plenum, a combustion chamber for combusting reacted oxidant/spent fuel; and, optionally, a fuel recirculation chamber below the combustion chamber, where the fuel recir- culation chamber is in part defined by semi-porous fuel cell positioning gasket, all within an outer generator enclosure, wherein the fuel cell gasket has a laminate struc ⁇ ture comprising at least a compliant fibrous mat support layer and a strong, yet flexible woven layer, which may contain catalytic particles facing the combustion chamber, where the catalyst, if used, is effective to further oxi ⁇ dize exhaust fuel and protect the open top end (37) of the fuel cells.
• US2006121327 describes a solid-oxide fuel cell assembly comprising a plurality of components having electrically- conductive mating surfaces there between, the surfaces are sealed by an electrically insulating gasket that include a mineral composition comprising about 66 mol percent MgO and about 33 mol percent Si02, the mineral composition being known mineralogically as forsterite.
• a brazing alloy may be applied to enhance bonding of the gasket into place.
• the gasket composition may include additions of AI 2 O 3 to enhance electrical resistivity while having little to no impact of matching expansion coefficients of the gasket and metal mating surfaces.
• a solution well known in the art is to increase the rough ⁇ ness of the flanges of the adjacent manifolds.
• the gasket has to be electrically insulating.
• the soft mica gasket is unreliable as an electrical insulator. Short circuits have been ob ⁇ served already at 100 V over a 1 mm gasket. As a conse- quence the soft mica gasket cannot do the job alone.
• the electrically insulating materials identified so far, are all too inflexible for establishing reliable gas sealing at the low compression forces that are preferred in SOC stack systems, where high forces are difficult to establish due to high temperatures and the onset of creep in all metals.
• the solution is to make a layered gasket, in which an elec ⁇ trically insulating layer is sandwiched between two soft gaskets (i.e. soft mica) .
• soft gaskets i.e. soft mica
• the sequence of materials is thereby: First a mounting in ⁇ terface (1) such as a metal manifold or flanged piping, then a soft, flexible gasket layer (2), then an electrical ⁇ ly insulating gasket layer (3) , then a soft, flexible gas ⁇ ket (4) and then the mounting interface of an SOC stack (5) .
• the combination of materials are well known, and the solution can be the same as recom- mended by the ASME standards and known in the art, such as roughness of the mounting interfaces 1 and 5 (manifolds, flanges and SOC stack mounting interface) .
• a new method of fixing in combination with the gasket sandwich layers is introduced according to the present invention. Any one or more of the gasket layers is manufactured with one or multiple holes, indents or bulges in the sealing area. This can be done when the gasket layer is cut to shape.
• a gasket layer adjacent to a gasket layer with the holes or indents will then bulge into the holes or indents, which establish the required fix of the gasket layers relative to each oth ⁇ er.
• a gasket layer adjacent to a gasket layer with a bulge will achieve an indent at the location oppo ⁇ site the bulge, when the gasket layers are sandwiched to- gether under compression, which also establish the required fix of the gasket layers relative to each other.
• This solu ⁇ tion can for instance be applied to the mid gasket layer, which is more rigid than the two surrounding gasket layers of the gasket sandwich.
• Fig. 1 shows a cross sectional view of a gasket according to an embodiment of the invention DETAILED DESCRIPTION
• a solid oxide cell stack system comprising a plurality of stacked cells has a cell stack with mounting interfaces for mounting applications to the stack, i.e. process gas piping or process gas mani ⁇ folds.
• the applications to be connected to the stack have mounting interfaces, such as flanges.
• the mounting interfaces further com ⁇ prise at least one gasket to be mounted in between the stack mounting interfaces and the adjacent mounting inter- faces of the applications.
• the gasket comprise two layers, a first and a third layer which have these properties and are flex ⁇ ible enough to compensate for them.
• Flexible enough means that it can compensate for the mentioned movements, vibra ⁇ tions and surface defects during normal operation and start-up / shut-down cycles of the SOC cell stack system without breaking or leaking.
• the gasket further comprise a second gasket layer which is sandwiched between the first and the third layer which has electrically insulating prop ⁇ erties which are sufficient to prevent short-circuiting of the cell stack and electrical connection of the stack to the mounted applications during normal operation and start ⁇ up / shut-down cycles of the SOC cell stack system.
• Fig. 1 a side cut view of the gasket according to this embodi ⁇ ment can be seen, position number 1 and 3 shows the flexi- ble layers and position number 2 shows the electrically in ⁇ sulating layer.
• all three gasket layers are made of mica
• the first and the third layer are made of a mica material with properties providing the mentioned necessary flexibility.
• the second layer less flexible than the first and the third layer has properties providing the necessary electrical insulation.
• the tensile strength of the second layer is between 60 and 180 N/mm2, preferably between 90 and 150 N/mm2.
• the compressive strength at 200°C of the second layer is between 180 and 300 N/mm2, prefera ⁇ bly between 220 and 260 N/mm2.
• the flexural strength of the second layer is between 150 and 250 N/mm2, preferably between 140 and 200 N/mm2.
• the thickness of each of the gasket layers is between 0.2 mm and 15 mm, preferably between 0.4 and 5 mm.
• the thickness of each of the layers can be varied to achieve the necessary flexibility, sealing and electrical insulation.
• the flexibility of at least the first and the third layer is utilized to provide a fix between each of the gasket layers and further between the gasket and the adjacent mounting interfaces. Indenta- tions, holes or bulges are made in at least one of the three gasket layers (i.e. in the second layer) to provide fixation of the layers relative to each other.
• the same princi ⁇ ple is utilized to provide fixation of the gasket relative to the adjacent mounting interfaces in contact with the gasket, to prevent movement in the plane of the mounting interfaces. Accordingly, holes, bulges or indents are made in the mounting interfaces in contact with the gasket. When under compression, this fixes the gasket relative to the mounting interfaces.
• an adhesive can be ap- plied to one or more of the gasket layers, to provide a simple fixation of the layers at least during assembly and mounting of the gasket in the SOC stack system.
• Adhesive may also be applied between the gasket and at least one of the adjacent mounting interfaces, likewise to provide a simple fixation of the elements during assembly of the gas ⁇ ket in the SOC system.
• the gasket is mounted between an SOC stack and a process gas manifold which is to be connected to the SOC stack (this is normally called "external manifolding" .
• a SOC stack system comprising a plurality of stacked cells and a plurality of mount ⁇ ing interfaces is assembled. At least one sandwich struc ⁇ tured gasket with at least three layers is located between two mounting interfaces.
• the mounting interface may comprise a SOC stack and process gas connec ⁇ tions such as manifolds and flanged pipes.
• the assembly comprises the steps of manufacturing two gasket layers, the first and the third in the sandwich of a flexible gasket material. As discussed earlier, the material has to be flexible enough to compensate for vibrations, surface de- fects of the mounting interfaces and thermally originated movements and any other movements occurring during normal operation and start-up / shut-down procedures of the SOC stack.
• the gasket layers are manufactured to physically match the two mounting interfaces which they are mounted in-between.
• a further second gasket layer which is electrically insulating is also manufactured to physically match the two mounting interfaces as well as the first and the third gasket layer.
• the three gasket layers are assem ⁇ bled in the layer order 1 - 2 - 3, so the electrically in- sulating layer is sandwiched between the two flexible lay ⁇ ers.
• the two mounting interfaces i.e. manifold and SOC stack
• one way is to position the gasket sandwich on one of the two mounting interfaces, for instance on the mount- ing interface of the SOC stack.
• the other mounting interface for instance the manifold is mounted on the gas ⁇ ket surface opposite the first mounting interface, so the gasket is positioned in-between the two mounting interfaces and compression is applied, whereby the gasket is com- pressed between the two mounting interfaces and a gas tight sealing is accomplished.
• an adhesive is applied to at least two surfaces of the gasket layers before the three-layer gasket sandwich is assembled, to fix the layers together at least until the SOC stack system has been assembled.
• indenta ⁇ tions or holes are made in at least one of the three gasket layers before they are assembled. When the gasket is com- pressed, this provides fixation of the gasket layers rela ⁇ tive to each other during operation and thermal cycles of the stack system.
• the holes or indentations may be provided in the second and least flexible layer of the gasket, which provides the simplest manufacturing.
• At least one of the mounting interfaces compressing the gasket are made with holes, indentations or bulges to provide fixation of the gasket relative to the contacting mounting interface.
• the gasket layers may be made of mica, the second layer of the gasket being less flexible than the first and the third layer, but electrically insulating.
• Solid oxide cell stack system comprising a plurality of stacked cell units and mounting interfaces, the mounting interfaces comprising at least one gasket, wherein said gasket comprises a sandwich structure of at least three layers, a first and a third flexible layer which is flexi ⁇ ble enough to compensate for vibrations, surface defects of the mounting interfaces and thermally originated movements and a second electrically insulating layer positioned in between the first and the third layer.
• the layers are made of mica, the first and the third layer is more flexible than the second layer.
• Solid oxide cell stack system according to any of the preceding features, wherein the tensile strength of the second layer is between 60 and 180 N/mm2, preferably be ⁇ tween 90 and 150 N/mm2. 4. Solid oxide cell stack system according to any of the preceding features, wherein the compressive strength at 200°C of the second layer is between 180 and 300 N/mm2, preferably between 220 and 260 N/mm2. 5. Solid oxide cell stack system according to any of the preceding features, wherein the flexural strength of the second layer is between 150 and 250 N/mm2, preferably be ⁇ tween 140 and 200 N/mm2. 6.
• Solid oxide cell stack system according to any of the preceding features, wherein the thickness of each of first, second and third layer is between 0,2 mm and 15 mm prefera ⁇ bly between 0,4 mm and 5 mm. 7. Solid oxide cell stack system according to any of the preceding features, wherein indentations, holes or bulges are made in at least one of the three layers, to provide fixation of the layers relative to each other. 8. Solid oxide cell stack system according to feature 7, wherein holes are made in the second layer, to provide fix ⁇ ation of the layers relative to each other. 9. Solid oxide cell stack system according to any of the preceding features, wherein indentations, holes or bulges are made on at least one of the mounting interfaces which are in contact with the gasket to provide fixation of the gasket relative to the contacting mounting interfaces.
• Solid oxide cell stack system according to any of the preceding features, wherein an adhesive is applied between the three layers.
• Solid oxide cell stack system according to any of the preceding features, wherein said gasket is mounted between the cell stack and a process gas manifold.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Fuel Cell (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

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• 2014
  • 2014-04-04 ES ES14163492.3T patent/ES2643601T3/es active Active
  • 2014-04-04 EP EP14163492.3A patent/EP2927999B1/en active Active
  • 2014-04-04 DK DK14163492.3T patent/DK2927999T3/en active
• 2015
  • 2015-03-30 AU AU2015239662A patent/AU2015239662B2/en active Active
  • 2015-03-30 JP JP2016560690A patent/JP6644004B2/ja active Active
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  • 2015-03-30 US US15/122,479 patent/US10205179B2/en active Active
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