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US-12623183-B2 - Coupling device and combination and assembly thereof with a tube

US12623183B2US 12623183 B2US12623183 B2US 12623183B2US-12623183-B2

Abstract

The invention relates to a coupling device for a tube having a Palladium-based membrane deposited thereon, for use in separation and purification of hydrogen in a hydrogen separator or reactor. The coupling device has an inlet for gas and configured to couple said tube to the inlet; a body part with a cylindrical opening for receiving the tube and for receiving gas flow to the inlet; a nut, the body part and the nut being configured such that the nut can be screwed onto the body part at the opening; a stack of at least two sealing rings. The body part, the nut and sealing rings are configured such that the tube extends through an axial end portion of the nut, the sealing rings into the opening such that, in use, the sealing rings are compressed axially as a result of screwing the nut onto the body part so that the sealing rings sealingly engage the tube.

Inventors

  • Fausto Gallucci
  • Madan BINDRABAN

Assignees

  • TECHNISCHE UNIVERSITEIT EINDHOVEN

Dates

Publication Date
20260512
Application Date
20210831
Priority Date
20200901

Claims (17)

  1. 1 . A coupling device ( 10 ) for a tube ( 12 ) having a Palladium-based membrane deposited thereon, the tube for use in separation and purification of hydrogen in a hydrogen separator or reactor, the coupling device having an inlet ( 14 ) for a gas and configured to couple said tube to the inlet so that the gas can be supplied via the inlet into the tube, the coupling device comprising: a body part ( 5 ) with a cylindrical opening ( 6 ) for receiving the tube, the opening being arranged to receive gas flow to the inlet; and a nut ( 1 ), wherein the body part and the nut being configured such that the nut can be screwed onto the body part at the opening; the coupling device further having a stack ( 16 ) of at least two sealing rings ( 3 , 4 ) provided between an end portion ( 20 ) of the body part surrounding the opening and an axial end portion ( 18 ) of the nut, wherein the body part, the nut and the stack of sealing rings are configured such that the tube extends through the axial end portion of the nut, through the stack of sealing rings and into the opening such that, in use, the stack of sealing rings is compressed in an axial direction ( 8 ) of the stack as a result of screwing the nut onto the body part so that the sealing rings sealingly engage a circumferential surface ( 11 ) of the tube; and wherein a sealing ring ( 4 ) of the stack ( 16 ) of sealing rings ( 3 , 4 ), which sealing ring ( 4 ) in use contacts the end portion ( 20 ) of the body part ( 5 ) surrounding the opening ( 6 ), is a square or rectangular shaped O-ring having an axially protruding tapered ridge ( 22 ) facing the end portion ( 20 ) of the body part, wherein the end portion of the body part has a correspondingly tapered or chamfered portion ( 24 ) for receiving therein the ridge ( 22 ).
  2. 2 . Coupling device according to claim 1 , wherein the stack ( 16 ) of sealing rings ( 3 , 4 ) is a stack of two to eight sealing rings.
  3. 3 . Coupling device according to claim 1 , wherein the sealing rings ( 3 , 4 ) are made of graphite, mica or copper.
  4. 4 . Coupling device according to claim 1 , wherein sealing rings ( 3 , 4 ) of the stack ( 16 ) are square or rectangular shaped O-rings.
  5. 5 . Coupling device according to claim 1 , further comprising a metal ring ( 2 ) on top of the stack of sealing rings ( 3 , 4 ), the metal ring ( 2 ) being arranged between the axial end portion ( 18 ) of the nut and the stack ( 16 ), so that a compressive force is exerted from the axial end portion of the nut to the stack of sealing rings via the metal ring.
  6. 6 . Coupling device according to claim 1 , wherein the body part ( 5 ) and/or the nut ( 1 ) are made of a stainless steel or a low carbon alloy.
  7. 7 . Coupling device according to claim 1 , wherein a plurality of threads ( 26 ) on the nut ( 1 ) and/or on the body part ( 5 ) have a coating made of silver or graphite, the plurality of threads arranged to screw the nut on the body part.
  8. 8 . Combination of the coupling device ( 10 ) according to claim 1 , and the tube ( 12 ) having the Palladium-based membrane deposited thereon, for use in separation and purification of hydrogen in the hydrogen separator or reactor.
  9. 9 . The combination of claim 8 , wherein the tube ( 12 ) is porous.
  10. 10 . An assembly ( 100 ) comprising the coupling device ( 10 ) according claim 1 , and the tube ( 12 ) having the Palladium-based membrane deposited thereon, for use in separation and purification of hydrogen in the hydrogen separator or reactor, wherein the tube extends through the axial end portion of the nut, through the stack of sealing rings and into the opening, wherein the stack of sealing rings is compressed in an axial direction of the stack as a result the nut being screwed onto the body part so that the sealing rings sealingly engage a circumferential surface of the tube.
  11. 11 . The assembly ( 100 ) of claim 10 , wherein the tube ( 12 ) is porous.
  12. 12 . The assembly ( 100 ) of claim 11 , wherein the tube ( 12 ) is made of a ceramic material.
  13. 13 . The combination of claim 9 , wherein the tube ( 12 ) is made of a ceramic material.
  14. 14 . Coupling device according to claim 2 , wherein the stack ( 16 ) of sealing rings ( 3 , 4 ) is a stack of three to five sealing rings.
  15. 15 . Coupling device according to claim 14 , wherein the stack ( 16 ) of sealing rings ( 3 , 4 ) is a stack of four sealing rings.
  16. 16 . Coupling device according to claim 1 , wherein the axially protruding tapered ridge ( 22 ) is a circumferential ridge.
  17. 17 . Coupling device according to claim 1 , wherein the ridge and the tapered portion are dimensioned such that the ridge exerts a force having a radial component on the tapered portion as a result of axial compression of the sealing ring ( 4 ).

Description

The present invention relates to a coupling device for a tube having a Palladium-based membrane deposited thereon, the tube for use in separation and purification of hydrogen in a hydrogen separator or reactor. The invention further relates to a combination and to an assembly of such a coupling device and such a tube. Sealing of Pd-based (Palladium-based) membrane layers deposited on ceramic tubular supports represents a challenging task: preliminary tests showed gas leak problems after some thermal cycles, due to the detachment of the Pd membrane layer that is deposited on the glass used to connect the ceramic dense and porous parts. This leakage would decrease the separation efficiency of the membranes and thus the quality of the hydrogen produced. Solving this problem will make the membranes closer to industrial applications. Chen et al. (Chen W, Hu X, Wang R, Huang Y. On the assembling of Pd/ceramic composite membranes for hydrogen separation. Sep Purif Technol Mar 2010; 72(1):92e7) described a method using graphite ferrules instead of using standard metal ferrules. The authors have shown that these graphite ferrules could successfully seal the membrane with Swagelok® connectors. Even at very high pressures up to 50 bar, the nitrogen leakage rate over the connectors was only about 0.35 ml/min. To seal the membranes with Swagelok® fittings of 10 mml·D. (code: SS-10M0-6), graphite ferrules of 10 mm I.D. (purchased from CHROMalytic TECH(nology) Pty Ltd) were used instead of the standard metal ones. Ferrules were opened from inside with a rotating cutter with sharp edges to in-crease the inner diameter of the ferrules in order to make them fit to the membranes (with an O.D. between 10 and 10.4 mm). Before sealing the membrane with the opened ferrules, the ferrules were first conditioned in the Swagelok® fitting with a dummy Stainless steel (316L) rod to form the ferrules to the right shape. The diameter of the dummy is equal to the diameter of the membrane to be sealed. The connectors were tightened with about 20-30 Nm (torque wrench) to form them with the right shape and to get a smooth inner surface. Reference is made in this regard to Fernandez et al. (Ekain Fernandez, Arash Helmi, Kai Coenen, Jon Melendez, Jose Luis Viviente, David Alfredo Pacheco Tanaka, Martin van Sint Annaland, Fausto Gallucci, Development of thin Pd—Ag supported membranes for fluidized bed membrane reactors including WGS related gases, International Journal of Hydrogen Energy, Volume 40, Issue 8, 2015, Pages 3506-3519). See FIGS. 5a and 5b, in which FIG. 5a shows a 316L dummy rod with graphite ferrule and FIG. 5b shows a connector with pre-treated ferrule (shiny inner surface), also with reference to Fernandez et al. FIG. 6a shows a Pd membrane (E80 e PdeAg membrane, thickness 4.5 micron) before connecting to the Swagelok® connectors, while FIG. 6b shows the same membrane after connecting to the Swagelok® connectors. Again reference is made to Fernandez et al. Although the sealing is effective in making the membrane more gas tight compared to previous cases, it is still a point of attention as most of the leakages are still coming from that zone. An extensive study on the stability of the membrane and sealing has been carried out showing that the membrane with 2 sealings has double the leakages than the one with 1 sealing. And the membrane where the sealing can be applied with higher torque, has less leakages that the one where the torque applied is less (see FIG. 7, showing relative nitrogen permeance of the membranes 1a to 3 in the long-term membrane test. Reference is made to De Nooijer et al. (de Nooijer, N., Plazaola, A. A., Rey, J. M., Fernandez, E., Tanaka, D. A. P., Annaland, M. S., Gallucci, F. Long-term stability of thin-film Pd-based supported membranes (2019) Processes, 7 (2), art. no. 106). It is an object to develop a sealing method that decreases the leakages and is more stable and possibly reusable. It is an object to provide an improved coupling device and an improved combination and assembly of such a coupling device and a tube having a Palladium-based membrane deposited thereon. It is an object to provide a coupling device, combination and assembly of such a coupling device and a tube having a Palladium-based membrane deposited thereon, having an improved sealing. According to the present invention, a coupling device is provided as defined in claim 1. Embodiments of the coupling device are defined in the dependent claims. The invention also relates to a combination as defined in claim 9 and an assembly as defined in claim 11. Embodiments of the coupling device as defined below are also applicable to the combination and the assembly. As defined in claim 1, the invention provides a coupling device for a tube having a Palladium-based membrane deposited thereon, the tube for use in separation and purification of hydrogen in a hydrogen separator or reactor. The coupling device has an inlet for a gas and configured to c