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EP-4739453-A1 - WELDED JOINT BETWEEN A METALLIC HYDROGEN SEPARATION MEMBRANE AND A METALLIC CONNECTOR

EP4739453A1EP 4739453 A1EP4739453 A1EP 4739453A1EP-4739453-A1

Abstract

A welded joint between a metallic connector and at least a metallic core of a metallic hydrogen separation membrane comprising a fusion weld formed from and between the metallic connector and at least the metallic core of the metallic hydrogen separation membrane, wherein the connector may be formed of a different metal or metal alloy to the metallic core of the hydrogen separation membrane, and wherein the fusion weld includes a sealing portion that provides a continuous seal between the metallic connector and at least the metallic core of the metallic hydrogen separation membrane and the weld metal of the sealing portion comprises less than 40% by mass of metal from the metallic core of the metallic hydrogen separation membrane.

Inventors

  • EDWARDS, Sandy
  • Viano, David
  • Langley, Matthew
  • INGLE, Riley

Assignees

  • Commonwealth Scientific and Industrial Research Organisation

Dates

Publication Date
20260513
Application Date
20240704

Claims (20)

  1. 1 . A welded joint between a metallic connector and at least a metallic core of a metallic hydrogen separation membrane comprising a fusion weld formed from and between the metallic connector and at least the metallic core of the metallic hydrogen separation membrane, wherein the connector is formed of a different metal or metal alloy to the metallic core of the hydrogen separation membrane, and wherein the fusion weld includes a sealing portion that provides a continuous seal between the metallic connector and at least the metallic core of the metallic hydrogen separation membrane, the sealing portion having a weld metal composition that comprises less than 40% by mass of metal from the metallic core of the metallic hydrogen separation membrane.
  2. 2. The welded joint according to claim 1 , wherein the weld metal of the sealing portion has a substantially homogenous composition throughout the volume of weld metal.
  3. 3. The welded joint according to claim 1 or 2, wherein the sealing portion comprises at least 80% of the weld metal, preferably between 80 to 100% of the weld metal.
  4. 4. The welded joint according to claim 1 , 2 or 3, wherein the weld metal of the sealing portion comprises at least one of: less than 35% by mass of metal from the metallic core of the metallic hydrogen separation membrane; less than 30% by mass of metal from the metallic core of the metallic hydrogen separation membrane; less than 25% by mass of metal from the metallic core of the metallic hydrogen separation membrane.
  5. 5. The welded joint according to any preceding claim, wherein no portion of the volumetric composition of the weld metal of the sealing portion comprises no more than 40% by mass of metal from the metallic core of the metallic hydrogen separation membrane, preferably no more than 35% by mass of metal from the metallic core of the metallic hydrogen separation membrane.
  6. 6. The welded joint according to any preceding claim, wherein the connector may be comprised of at least one of: steel, stainless steel, nickel-chromium-iron alloy, brass, Inconel, Incoloy, or combinations thereof.
  7. 7. The welded joint according to any preceding claim, wherein at least the metallic core of the hydrogen separation membrane comprises a group 5 based metal or metal alloy, preferably a vanadium, tantalum or niobium metal or metal alloy, more preferably vanadium or a vanadium alloy.
  8. 8. The welded joint according to any preceding claim, wherein the metallic core comprises a non-porous body, preferably a non-porous tube.
  9. 9. The welded joint according to any preceding claim, wherein the metallic core and the hydrogen separation membrane is tubular, and the connector is tubular.
  10. 10. The welded joint according to any preceding claim, wherein the welded joint comprises a laser welded connection, an electron beam welded connection, or an arc welded connection.
  11. 1 1. The welded joint according to any preceding claim, wherein the welded joint comprises an autogenous weld.
  12. 12. The welded joint according to any preceding claim, wherein the metallic core of the metallic hydrogen separation membrane is mounted on or against a connector formation of the connector, the metallic core and the connector formation contacting at a connection interface in which an end face of the metallic core is proximate to, substantially abuts or overlaps an adjoining face of the connector formation; and the welded joint connects at least the metallic core of the hydrogen separation membrane and the connector about the connection interface.
  13. 13. The welded joint according to claim 12, comprising a continuous weld which extends circumferentially around and over the connection interface.
  14. 14. The welded joint according to claim 12 or 13, wherein the end face of at least the metallic core of the hydrogen separation membrane at the connection interface comprises a substantially square edge.
  15. 15. The welded joint according to claim 12, 13 or 14, wherein the connector formation comprises a tapered, sloped or bevelled section configured to receive the end section of the metallic core of the hydrogen separation membrane thereon.
  16. 16. The welded joint according to claim 15, wherein the connector formation comprises a tapered surface, having a taper angle of 15° to 60°, preferably 15° to 45°, more preferably 15° to 30°, and yet more preferably around 30°.
  17. 17. A method of joining and sealing at least a metallic core of a hydrogen separation membrane to a metallic connector comprising: mounting an end section of at least the metallic core of the metallic hydrogen separation membrane on or against a connector formation of a metallic connector, the connector being formed of a different metal or metal alloy to the metallic core of the hydrogen separation membrane, the metallic core and the connector formation contacting at a connection interface in which an end face of at least the metallic core of the hydrogen separation membrane is proximate to, substantially abuts or overlaps an adjoining face of the connector formation; welding at least the metallic core of the hydrogen separation membrane to the connector to form a welded joint at and over the connection interface comprising a fusion weld, said fusion weld including a sealing portion that provides a continuous seal between the metallic connector and at least the metallic core of the metallic hydrogen separation membrane, the sealing portion having a weld metal composition that comprises less than 40% by mass of metal from the metallic core of metallic hydrogen separation membrane, thereby forming a continuous fusion welded seal between the metallic connector and at least the metallic core of the metallic hydrogen separation membrane.
  18. 18. The method according to claim 17, using a welded joint according to any one of claims 1 to 16.
  19. 19. The method according to claim 17, or 18, wherein the weld metal of the sealing portion has a substantially homogenous composition throughout the volume of weld metal.
  20. 20. The method according to claim 17, 18 or 19, wherein the sealing portion comprises at least 80% of the weld metal, preferably between 80 to 100% of the weld metal.

Description

WELDED JOINT BETWEEN A METALLIC HYDROGEN SEPARATION MEMBRANE AND A METALLIC CONNECTOR TECHNICAL FIELD [001 ] A welded joint between a metallic hydrogen separation membrane to a metallic connector and the composition thereof is disclosed, as well as a method of joining a metallic hydrogen separation membrane to a metallic connector, e.g., sealably joining. The joint may be particularly applicable for joining and sealing a tubular membrane, such as a vanadium-based tubular membrane, to a stainless steel gas fitting. However, it should be appreciated that the joint could be used to join and seal any metallic type of hydrogen separation membrane to any type of metallic fitting or body. BACKGROUND [002] The following discussion is intended to facilitate a background understanding. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of the application. [003] Hydrogen (H2) does not occur naturally in great abundance, and in industrial practice it may be produced by the conversion of a hydrocarbon fuel such as coal, petroleum or natural gas, through the decomposition of ammonia (NH3), or from the electrochemical decomposition of water. Each of these production routes produces an impure gas stream containing H2 plus unreacted feed gases (e.g., CH4, H2O, NH3) and by-products such as CO2, CO and N2. For many applications, the H2 must be separated from this mixed gas stream. [004] Membrane-based separation technology can be used for the separation of H2 from mixed gas streams. Broadly speaking, a membrane is a near two- dimensional structure which is selectively permeable to one species. In the context of gas separation, a membrane allows one species to selectively permeate (H2), while blocking other species (e.g. CO, CO2, H2O, N2 etc.). Hydrogen-selective membranes can be created from inorganic, metallic or ceramic materials, each of which has characteristic hydrogen throughputs, operating temperatures and selectivity. [005] Palladium is the best known alloy membrane material, having an ability to permeate hydrogen between 300 to 600 °C whilst being tolerant to syngas species such as CO and H2O. However, the high cost of palladium (AUD 80 to 160/g Pd (June 2023)), has driven research towards minimising its consumption, most notably through alloying with less-expensive metals, and minimising thickness by depositing very thin (< 5 pm) layers on support structures with very fine pores. [006] A number of other metals exhibit very high hydrogen permeability, most notably vanadium, titanium, tantalum, niobium and zirconium. At 400 °C, the hydrogen permeability of these metals is around two orders of magnitude greater than palladium, and the raw materials prices are significantly lower. Of these metals, vanadium has the widest alloying range, which means it has the widest scope for modifying the alloy properties to meet the demands of a vanadium- based membrane. One example of vanadium-based membranes is taught in the Applicant's United States patent publication No. US20150368762A1 . [007] Vanadium-based membranes are typically connected and sealed with another tube or pipe to provide a flow path for the extracted H2 and to prevent passage of non-H2 gas species through the membrane. The sealing/joining of membranes to connections is crucial for the successful application of the V-based membrane technology in the separation of high purity hydrogen from a mixed gas feed containing hydrogen. In this regard, high purity hydrogen suitable for use in fuel-cell electric vehicles, FCEVs, require >99.97% purity as set out in ISO 14687 standard as well as maximum limits on individual gas species such as NH3 and N2. Failure of seals results in contamination of the hydrogen product, which means the membranes are no longer ‘fit for purpose’ for producing high purity hydrogen. [008] One connection and sealing technique for tubular vanadium-based membranes utilises brazing between a V-based membrane to a metallic fitting, for example an end cap or connection fitting. One example of an arrangement that joins a vanadium-based membrane to a metallic fitting is taught in international patent publication No. W02019000026A1 which teaches a brazing technique for joining and sealing a vanadium-based membrane to a metallic connector in which a filler or brazing metal is used to form a bridging section of filler metal between the vanadium-based membrane and connector over the connection interface. [009] WO2019000026A1 also teaches (at paragraphs 99 to 102) that the subject brazing process was developed in preference to laser welding. It should be appreciated that a brazing process comprises melting a braze (filler) material into a joint without melting the adjoining metal pieces being joined, to connect those metals using the braze metal. Brazing does not melt the base materials to be