How to manufacture a high pressure tank

Abstract

To provide a method for manufacturing a tank for storing or containing a fluid under pressure, such as for storing, containing or channeling hydrogen, natural gas or a hydraulic fluid, and a method for manufacturing a pipe for containing or channeling a fluid under pressure.SOLUTION: A method of the present invention is less complex than known procedures, can be employed in a continuous or semi-continuous manner, and allows for a lower thickness of a shell made from fibers. The method of the present invention includes the steps of: providing a liner having a cylindrical portion with two ends and two dome portions at the respective ends of the cylindrical portions, or a liner having a cylindrical portion and one or two open ends; fabricating a tube of fiber filaments by means of a pull-winding method; and wrapping the tube of fiber filaments onto the liner such that at least the cylindrical portion of the liner is enclosed by the tube of fiber filaments.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a high pressure tank for storing or containing a fluid (liquid or gas such as hydrogen or natural gas) under pressure. [Background technology]

[0002] High pressure tanks, especially for hydrogen or natural gas storage in vehicles or gas stations, are gaining interest. Simple type 1 metallic tanks, such as those made of steel and aluminium, can safely store gases up to maximum pressures of 17.5 MPa (aluminium) to 30 MPa (steel), while fibre filament reinforced (type 2) or filament composite (type 3 or type 4) tanks can safely store gases up to maximum pressures of 85 MPa.

[0003] Type 2 tanks are constructed by fiber filaments wound with carbon, aramid, or glass fibers around a metal core. Type 3 tanks are made from composite materials including carbon, aramid, or glass fibers around a metal liner. The metal component (in the case of type 3 tanks) is provided to avoid gas diffusion through the composite material. Type 4 tanks are composite tanks, for example carbon, aramid, or glass fibers with a polymer liner.

[0004] To create those type 2, type 3 and type 4 tanks, the fiber filaments are carefully placed one by one around a metal or polymer liner and held together using a matrix, usually made of epoxy resin (although other materials may be possible). Such a method is described, for example, in patent application WO 2013 / 023363, published on 14 November 2013. The shells made from the fibers usually have a thickness of 3 mm to 30 mm.

[0005] This method of weaving individual strands of fiber makes the construction complex, time consuming and therefore costly.

[0006] It is therefore an object of the present invention to provide a method for manufacturing high-pressure tanks or other pressure-resistant fluid storage vessels, such as hydrogen or natural gas storage tanks, which is less complicated than known procedures, can be used in a continuous or semi-continuous manner and allows for a reduced thickness of the shell made from the fibers, taking into account pressure safety. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] US Patent Application Publication No. 2013 / 299505 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In one embodiment, the present invention relates to a method of manufacturing a tank for storing or containing a fluid under pressure, comprising the steps of: (a) providing a liner having a cylindrical portion with two ends and two dome portions at each end of the cylindrical portion; (b) creating a tube of fiber filament using a pullwind method; (c) wrapping the tube of fiber filaments onto the liner such that at least a cylindrical portion of the liner is surrounded by the tube of fiber filaments.

[0009] In another embodiment, the present invention relates to a method of manufacturing a pipe for containing or conducting a fluid under pressure, comprising the steps of: (a) providing a liner having a cylindrical portion with one or two open ends; (b) creating a tube of fiber filament using a pullwind method; (c) wrapping the tube of fiber filaments onto the liner such that the cylindrical portion of the liner is surrounded by the tube of fiber filaments.

[0010] The pullwind process is a commonly applied method for making high performance composite tubes and combines traditional pulltrusion and continuous filament winding technologies. In the pullwind process, the longitudinal fibers are co-extruded by pultrusion of hoop-wound continuous fibers.

[0011] In one embodiment of step (b), the longitudinal fibers are arranged as an outer filament layer or as an inner filament layer of the tube of fiber filaments. The outer filament layer may be arranged on the outer and / or inner surface of the tube of fiber filaments, and the inner filament layer is defined as not touching the surface of the tube of fiber filaments. In addition to the longitudinal fibers, one or more hoop-wrapped layers of fibers are wound around or inside the longitudinal fibers. The hoop-wrapped layers of fibers may be wound at an oblique angle around the longitudinal fibers, typically at an angle of 20° to about 79°, preferably about 30° to about 60°, more preferably about 45°. Fibers wound at an oblique angle around the longitudinal fibers can function to counteract twisting and bending forces. Alternatively or in addition, the hoop-wrapped layers of fibers may be wound around or inside the longitudinal fibers at a transverse angle of about 80° to about 89.9° (or about 0.1° to about 10°) around the longitudinal fibers. Due to the slightly helical nature of the winding and the lateral movement of the wound roving, the angle is not truly 90°, but progresses by one band width per revolution. The fibers wrapped at a transverse angle around the longitudinal fibers can act to absorb radial forces resulting from the internal pressure of the metal liner. Any combination of longitudinal fiber layers and hoop-wrapped fiber layers is possible to maximize absorption of forces on the tube.

[0012] When more than one hoop wound layer is disposed within the tube wall or on the outer surface of the inner or outer tube wall of a tube of fiber filaments, the windings of the hoop wound layers are preferably staggered in a clockwise and counterclockwise direction, whether diagonal or transverse.

[0013] In another embodiment, a tube of fiber filaments may be wound around the inner and / or outer surface of a core of another material, such as a core of a foam material, a core of an elastomeric polymer, a core of a rubber, or a core of a composite material. In yet another embodiment, two tubes of fiber filaments are wound around a core of another material, such as a core of a foam material, a core of an elastomeric polymer, or a core of a rubber, with one tube of fiber filaments wound around the inner surface of the core and the other tube of fiber filaments wound around the outer surface of the core material.

[0014] In the method for manufacturing a tank for storing or containing a fluid under pressure and / or in the method for manufacturing a pipe for containing or conducting a fluid under pressure, the tube of fiber filaments may be secured to the liner by heat shrinking the fiber filaments onto the liner. Of course, this assumes that the fiber filaments are heat shrinkable. In another embodiment of the invention, the tube of fiber filaments may be secured to the liner by gluing the fiber filaments onto the liner.

[0015] Thus, in another embodiment, the present invention relates to a method of manufacturing a tank for storing or containing a fluid under pressure, comprising the steps of: (a) providing a liner having a cylindrical portion with two ends and two dome portions at each end of the cylindrical portion; (b) creating a tube of fiber filament using a pullwind method; (c) winding the tube of fiber filaments onto the liner such that at least a cylindrical portion of the liner is surrounded by the tube of fiber filaments; (d) applying heat to shrink the tube of fiber filaments onto the liner and / or adhere the tube of fiber filaments onto the liner.

[0016] In yet another embodiment, the present invention relates to a method of manufacturing a pipe for containing or conducting a fluid under pressure, comprising the steps of: (a) providing a liner having a cylindrical portion with one or two open ends; (b) creating a tube of fiber filament using a pullwind method; (c) wrapping the tube of fiber filaments onto the liner such that the cylindrical portion of the liner is surrounded by the tube of fiber filaments; (d) applying heat to shrink the tube of fiber filaments onto the liner and / or adhere the tube of fiber filaments onto the liner.

[0017] Care should be taken when placing the fiber filaments on the liner to ensure that the inner body can expand even if the temperature inside the tank increases.

[0018] In a preferred embodiment of any of the above-mentioned embodiments, the liner is made of metal, preferably aluminum or steel. For tanks that store or contain fluids under pressure, the metal liner may consist of a cylindrical section welded to a dome section on each side of the cylindrical section.

[0019] Alternatively, the liner may be made of a plastic material that provides a diffusion barrier for the fluid.For tanks that store or contain fluids under pressure, the plastic liner may consist of a cylindrical portion bonded to a dome portion on each side of the cylindrical portion.

[0020] In both of the above embodiments, whether the liner is metal or plastic material, the dome portion may be held by a central rod extending along the central axis of the cylindrical portion, in which case the central rod may be used as a fluid conduit if hollow. In yet another embodiment, the dome portion may be held by an array of rods disposed around the cylindrical portion, in which case the walls of the cylindrical portion may be double-walled or single-walled, with the array of rods disposed between the walls on the outside or inside of the fiber composite tube. In embodiments using an array of rods to hold the dome at the end of the cylindrical portion, the rods may be hollow and may serve to cool and / or heat the liner and its contents or serve as fluid conduits.

[0021] In another preferred embodiment of any of the above-mentioned embodiments, the surrounding textile filaments are made of carbon, aramid, fiberglass, or any combination thereof.

[0022] The method according to the invention has been found to be very well suited for the continuous or semi-continuous production of tanks for storing or containing fluids under pressure, in particular high pressure tanks of type 2, or pipes for containing or conducting fluids under pressure, since it is possible to achieve a high throughput at a relatively low cost. Furthermore, the thickness of the pressure-resistant polymer shell is reduced, in particular in the best case and depending on the desired pressure resistance, to 5 mm or even 3 mm. This is because it is possible to place the fibers at an angle of about 90° from the longitudinal axis of the core and thus completely absorb the radial stresses caused by the pressure of the fluid. At the same time, the amount of fibers in other directions can be reduced compared to other fiber placement techniques, resulting in the desired reduction in the overall wall thickness.

[0023] If made of metal, the inner liner can be made by providing a metal tube of the desired diameter and wall thickness and welding two end caps onto it. Metal liners can also be made by deep drawing a metal tube of the desired diameter and wall thickness with one deep drawn end cap, two deep drawn end caps, one on each end, or one deep drawn end cap welded to the end, by additive manufacturing, or by die casting the metal into the appropriate shape. If made of polymer, the liner may be manufactured by extrusion or adhesive bonding.

[0024] In yet another embodiment of the invention, an intermediate layer of an elastic material, such as a foam material, an elastomeric polymer, or rubber, is provided between the liner and the fiber filaments, for example to offset the differential expansion between the metal core (which expands when heated) and the composite shell (which typically does not expand appreciably when heated).

Claims

1. 1. A method of manufacturing a tank for storing or containing a fluid under pressure, comprising the steps of: (a) providing a liner having a cylindrical portion with two ends and two dome portions at each end of the cylindrical portion; (b) creating a tube of fiber filaments using a pullwind method; (c) wrapping the tube of fiber filaments onto the liner such that at least the cylindrical portion of the liner is surrounded by the tube of fiber filaments.

2. (a) providing a liner having a cylindrical portion with two ends and two dome portions at each end of the cylindrical portion; (b) creating said tube of fiber filaments using a pullwind process; (c) winding the tube of fiber filaments onto the liner such that at least the cylindrical portion of the liner is surrounded by the tube of fiber filaments; 2. The method of claim 1, further comprising: (d) applying heat to shrink the tube of fiber filaments onto the liner and / or adhere the tube of fiber filaments onto the liner.

3. 1. A method of manufacturing a pipe for containing or conducting a fluid under pressure, comprising the steps of: (a) providing a liner having a cylindrical portion with one or two open ends; (b) creating a tube of fiber filaments using a pullwind method; (c) wrapping the tube of fiber filaments onto the liner such that the cylindrical portion of the liner is surrounded by the tube of fiber filaments.

4. (a) providing a liner having a cylindrical portion with one or two open ends; (b) creating a tube of fiber filaments using a pullwind method; (c) wrapping the fiber filament tube onto the liner such that the cylindrical portion of the liner is surrounded by the fiber filament tube; 4. The method of claim 3, comprising: (d) applying heat to shrink the tube of fiber filaments onto the liner and / or adhere the tube of fiber filaments onto the liner.

5. 5. The method according to claim 1, wherein in step (b) the longitudinal fibers are arranged as an outer filament layer, or as an inner filament layer, or as an intermediate filament layer of the tube of fiber filaments.

6. The method of claim 5 , wherein one or more hoop-wrapped layers of fiber are wrapped around or within the warp fibers.

7. 7. The method of claim 6, wherein the hoop-wrapped layer of fibers is wrapped around the longitudinal fibers at an inclination angle of from 20° to about 79°, preferably from about 30° to about 60°, more preferably about 45°.

8. 8. The method of claim 6 or 7, wherein the hoop-wrapped layer of fibers is wrapped around the longitudinal fibers at a transverse angle of about 80° to about 89.9°, or about 0.1° to about 10°.

9. 9. The method of any one of claims 1 to 8, wherein the liner is made of aluminum or steel.

10. The method of claim 1, wherein the surrounding fiber filaments are made of carbon, aramid, glass fiber, or any combination thereof.

11. The method according to any one of claims 1 to 10, wherein an intermediate layer is provided between the liner and the fibre filaments.

12. The method of claim 11 , wherein the intermediate layer is made of a foam material, an elastomeric polymer, or a rubber.

13. 13. The method according to claim 3 or 4, or any one of claims 5 to 12 depending on claim 3 or 4, wherein in step (b) the fibre filaments are wound around the inner and / or outer surface of the core.

14. 14. The method of claim 13, wherein two tubes of fiber filaments are wound around a core, one tube of fiber filaments wrapped around an inner surface of the core and the other tube of fiber filaments wrapped around an outer surface of the core.

15. 15. The method of claim 13 or 14, wherein the core is made of a foam material, an elastic polymer, a rubber, or a composite material.

16. 13. A method according to claim 1 or 2, or any one of claims 5 to 12 depending therefrom, wherein the dome portion is held by a central rod extending along a central axis of the cylindrical portion.

17. 13. A method according to claim 1 or 2 or any one of claims 5 to 12 depending thereon, wherein the dome portion is retained by an array of rods arranged around the cylindrical portion.