System for transporting liquid hydrogen, use thereof and manufacturing method thereof

Abstract

The present invention relates to a system for transporting liquid hydrogen, its use, and a method for manufacturing the same. The system comprises: a liquid hydrogen transport device; a liquid hydrogen receiving device; and a conduit in fluid communication with the liquid hydrogen transport device and the liquid hydrogen receiving device for conducting liquid hydrogen between the liquid hydrogen transport device and the liquid hydrogen receiving device. The conduit is characterized in that at least a section of the conduit is provided by a seamless tube made of austenitic stainless steel. The system is used to conduct pressurized liquid hydrogen at a pressure exceeding 100 bar in the conduit. For applications where space is limited, compressed liquid hydrogen can result in significantly higher storage density. An advantage of the present invention is its increased pressure resistance.

Description

[0001] This invention patent application is a divisional application based on the Chinese patent application with application date of September 12, 2018, application number 201880052523.7, and invention name “Liquid Hydrogen Transmission System”. Technical Field

[0002] The present invention relates to a system for transporting liquid hydrogen using liquid hydrogen transport equipment, a liquid hydrogen receiving device, and a conduit in fluid communication with the liquid hydrogen transport equipment and the liquid hydrogen receiving device, wherein the conduit is used to guide liquid hydrogen between the liquid hydrogen transport equipment and the liquid hydrogen receiving device.

[0003] Furthermore, the invention relates to a method for producing a system for transporting liquid hydrogen. Background Art

[0004] Applications using liquid hydrogen require cryogenic storage, as liquid hydrogen boils at approximately -253°C. Therefore, a material that can withstand these extreme conditions is required. Another issue is that hydrogen is highly flammable and explosive in its gaseous state. Yet another problem with hydrogen is hydrogen embrittlement. This effect is significant whenever hydrogen comes into contact with a metal surface, as individual hydrogen atoms will diffuse through the metal.

[0005] Welded pipes carry the risk of cracking within the weld zone. Furthermore, if cracks develop in pipes carrying liquid hydrogen, the hydrogen will immediately become gaseous due to its low boiling point. This gaseous hydrogen can accumulate in specific locations, creating a risk of explosion. Because cracks represent a larger surface area, hydrogen embrittlement can also lead to cracks in the material, potentially introducing hydrogen to the metal surface.

[0006] One aspect of the present invention provides a system for transporting liquid hydrogen that overcomes at least one of the above-mentioned disadvantages. Another aspect of the present invention provides a system for transporting liquid hydrogen that provides lower risk and higher standards for the transport of liquid hydrogen. Another aspect of the present invention provides a system for transporting liquid hydrogen that has pipes with the same or less fatigue than welded pipes while providing reduced weight. Summary of the Invention

[0007] At least one of the above aspects is addressed by a system for transporting liquid hydrogen, wherein at least a section of a conduit is provided by a seamless tube made of austenitic stainless steel comprising, in weight %, the following: C ≤ 0.080, 8.00 ≤ Mn ≤ 10.00, Si ≤ 1.00, P ≤ 0.030, S ≤ 0.030, 19.00 ≤ Cr ≤ 21.50, 5.50 ≤ Ni ≤ 7.50, 0.15 ≤ N ≤ 0.40, Mo ≤ 0.75, Cu ≤ 0.75, with the remainder being Fe and commonly present impurities.

[0008] In the present invention, the term "transfer of liquid hydrogen" is used synonymously with the term "transferring liquid hydrogen" to describe the process of transferring liquid hydrogen from point A to point B via a conduit.

[0009] In an embodiment according to the invention, the seamless pipe is made of austenitic stainless steel consisting of or containing the same above-mentioned elements but with a maximum content of C ≤ 0.040 in wt. %.

[0010] It should be noted that for those elements mentioned above that are contained in or composed of austenitic stainless steel and for which no lower limit of content is given, the minimum value in terms of weight % may be "0." Those elements are C, P, S, Mo and Cu.

[0011] Austenitic stainless steel alloys as defined above or below may optionally include one or more elements selected from the group consisting of Al, V, Nb, Ti, O, Zr, Hf, Ta, Mg, Pb, Co, Bi, Ca, La, Ce, Y, and B. These elements may be added during the manufacturing process to enhance, for example, deoxidation, corrosion resistance, hot ductility, and / or machinability. However, as is known in the art, the addition of these elements must be limited depending on the elements present. Thus, if these elements are added, the total content of these elements is less than or equal to 1.0% by weight.

[0012] The term "impurity" as used herein is intended to mean a substance that may contaminate an austenitic stainless steel alloy during industrial production due to raw materials (such as ores and waste) and due to various other factors in the production process, and is permitted to contaminate an austenitic stainless steel alloy within a range that does not adversely affect the austenitic stainless steel alloy as defined above or below.

[0013] In one embodiment, at least a portion of the conduit is provided by a seamless tube made of austenitic stainless steel comprising, in weight %, C ≤ 0.080, 8.00 ≤ Mn ≤ 10.00, Si ≤ 1.00, P ≤ 0.030, S ≤ 0.030, 19.00 ≤ Cr ≤ 21.50, 5.50 ≤ Ni ≤ 7.50, 0.15 ≤ N ≤ 0.40, Mo ≤ 0.75, Cu ≤ 0.75, the remainder being Fe and typically present impurities.

[0014] In another embodiment of the present invention, the seamless pipe is made of austenitic stainless steel consisting of or containing the same above-mentioned elements but with a maximum content in wt. % of C ≤ 0.040.

[0015] The above-mentioned austenitic stainless steel is called 21-6-9 stainless steel (also expressed as UNS S21900).

[0016] The 21-6-9 stainless steel has a high Mn content, a low Ni content, and additional N. It is characterized by high mechanical strength under harsh conditions, very good impact toughness even at very low temperatures, and very good high-temperature oxidation resistance.

[0017] Until now, pipes made from austenitic 21-6-9 stainless steel have only been available as welded pipes. For example, welded pipes are manufactured by bending flat steel sheets into pipes and welding the joints together to form a seam. Several other manufacturing steps may be described below.

[0018] A potential disadvantage of such welded pipes is the risk of rupture, with the weld zone being a preferred location for rupture. This was demonstrated in fatigue testing of 21-6-9 steel welded pipe. This is particularly problematic where the pipe is subjected to extreme conditions, such as high mechanical stresses, high or low temperatures, high temperature gradients, and high pressures or pressure gradients.

[0019] According to the present invention, the tube providing the conduit is a seamless tube.

[0020] The advantages of seamless pipes when compared to welded pipes are extended component life, increased design possibilities for reduced weight at equal strength, and better quality of the seamless pipe's internal shape.

[0021] Another advantage of seamless pipes over welded pipes is their ability to withstand higher hoop stresses. Thus, in impulse pressure tests, stress cycle (SN) curves are obtained, which are also known as Wheeler curve. The results show that for welded and seamless pipes with the same outer diameter and wall thickness, the seamless pipe will always experience higher hoop stress, regardless of the applied pressure. Therefore, it is possible to manufacture seamless pipes that have a smaller wall thickness than welded pipes but can withstand the same hoop stress. This results in material savings and weight reductions.

[0022] In one embodiment, the system for transporting liquid hydrogen is a filling station, wherein the liquid hydrogen transport device is a reservoir for liquid hydrogen, and wherein the liquid hydrogen receiving device is a pump nozzle.

[0023] In one embodiment, the liquid hydrogen delivery system is a vehicle, air vehicle, or watercraft, wherein the liquid hydrogen delivery device is a storage for liquid hydrogen, and wherein the liquid hydrogen receiving device is a hydrogen engine or a fuel cell.

[0024] It should be noted that, within the meaning of the present invention, the term "watercraft" should be understood in a broad sense, so that it covers all types of water vehicles, such as ships, boats, hovercraft and submarines. In addition, it should be mentioned that, within the meaning of the present invention, the term "aircraft" should be understood in a broad sense, so that it covers all types of airborne equipment, such as airplanes, helicopters, rockets, satellites and other space equipment.

[0025] In the foregoing and in the following detailed description of embodiments and claims, reference is made to an austenitic stainless steel tube or a method of making an austenitic stainless steel tube, and the features described apply to the tube and the method of making the tube.

[0026] In another embodiment of the present invention, the tube is obtained by a process comprising the steps of providing a melt of austenitic stainless steel comprising, in wt. %, C≤0.080, 8.00≤Mn≤10.00, Si≤1.00, P≤0.030, S≤0.030, 19.00≤Cr≤21.50, 5.50≤Ni≤7.50, 0.15≤N≤0.40, Mo≤0.75, Cu≤0.75, with the balance being Fe and typically present impurities; extruding a billet from the melt; hot forming the billet into a tubular hollow body; cooling the hollow body; and cold forming the hollow body into a tube.

[0027] In one embodiment, hot forming is achieved by hot rolling.

[0028] In one embodiment, a melt of austenitic stainless steel is provided, wherein the austenitic stainless steel comprises, in weight %, C ≤ 0.080, 8.00 ≤ Mn ≤ 10.00, Si ≤ 1.00, P ≤ 0.030, S ≤ 0.030, 19.00 ≤ Cr ≤ 21.50, 5.50 ≤ Ni ≤ 7.50, 0.15 ≤ N ≤ 0.40, Mo ≤ 0.75, Cu ≤ 0.75, with the remainder being Fe and commonly present impurities.

[0029] In another embodiment of the present invention, a melt of austenitic stainless steel is provided, wherein the austenitic stainless steel consists of or comprises the same above-mentioned elements but has a maximum content of C ≤ 0.040 in weight %.

[0030] In an embodiment according to the invention, the cold forming is achieved according to the invention by cold pilger milling or cold drawing.

[0031] Cold forming is a process used to form hollow metal bodies into tubes. Cold forming the resulting seamless tube not only changes its properties due to strain hardening during the cold forming process, but also reduces the tube's wall thickness, as well as its inner and outer diameters. Cold forming the hollow body into a tube, for example by pilger milling or cold drawing, allows for the production of tubes with precise dimensions.

[0032] Pilgrimage milling is a widely used method for reducing the size of tubes. The pilgrimage milling considered here is performed at room temperature and is therefore referred to as cold pilgrimage milling. During pilgrimage milling (in this method), a hollow body is pushed over a calibrated mandrel, which defines the inner diameter of the finished tube. The hollow body is engaged by two calibrated rollers, which define the outer diameter of the tube. These rollers roll the hollow body in the longitudinal direction on the mandrel.

[0033] At the beginning of the pilger milling process, a drive moves the hollow body into the chuck of the feeder. At the front point of the mill stand's return in the direction of feed of the hollow body, the rollers assume an angular position that allows the hollow body to be inserted into the rollers' infeed pockets and positioned between them. Two rollers, mounted perpendicular to each other at the mill stand, roll the hollow body by rolling back and forth parallel to the direction of feed. During the mill stand's movement between the front and rear points of return, the rollers stretch the hollow body onto a mandrel mounted inside the hollow body.

[0034] The rollers and mandrels are calibrated so that the gap formed between the rollers and the mandrel in the roller section, designated as the working diameter, decreases continuously from the wall thickness of the hollow body before forming to the wall thickness of the fully rolled tube. Furthermore, the outer diameter defined by the rollers decreases from the outer diameter of the hollow body to the outer diameter of the finished tube. Furthermore, the inner diameter defined by the mandrel decreases from the inner diameter of the hollow body to the inner diameter of the finished tube. In addition to the working diameter, the rollers also have a planing diameter. This planing diameter does not reduce the tube wall thickness or the inner or outer diameter, but rather serves to plane the surface of the tube being produced. When the rollers have reached the rear point of the roll stand's return, they assume an angular position in which they form an escapement pocket, allowing them to disengage from the tube.

[0035] The hollow body is fed in the feed direction at the front point of the roll stand's return, or at both the front point of the roll stand's return and the rear point of the roll stand's return. In one embodiment, each section of the hollow body can be rolled multiple times. In this embodiment, the number of steps required to feed the hollow body in the feed direction is significantly shorter than the distance traveled by the roll stand from the front point of the return to the rear point of the return. Multiple rolling of each tube section achieves uniform wall thickness and roundness, high surface quality, and uniform inner and outer diameters.

[0036] In order to achieve a uniform shape for the finished tube, in addition to the step-by-step feeding, the hollow body is also subjected to intermittent rotation about its axis of symmetry. In one embodiment, the rotation of the hollow body is provided at at least one return point of the rolling stand, i.e., as soon as the hollow body is disengaged from the rollers at the feed pocket and the release pocket, respectively.

[0037] In an embodiment of the present invention, the cold forming is achieved by pilger milling, and after the pilger milling, the tube is cold drawn through a drawing die.

[0038] In an embodiment of the present invention, the tube is cold drawn instead of, or after, pilger milling.

[0039] As considered here, the drawing is carried out at room temperature and is therefore called cold drawing.

[0040] Different methods of cold drawing can be used as embodiments of the present invention, namely tube drawing, core drawing and rod drawing. During the tube drawing process, the tube is drawn through a drawing die to reduce only the outer diameter of the tube without further defining the inner diameter of the tube. During core drawing and rod drawing, the inner diameter and wall thickness of the drawn tube are defined simultaneously by a mandrel. The mandrel is not fixed but is held by the tube itself or, in rod drawing, by a rod extending through the inner diameter of the tube. In one embodiment, in which a mandrel is applied during the drawing process, the drawing die and mandrel define an annular gap through which the tube is drawn. When a mandrel is used, the outer diameter, inner diameter and wall thickness can be reduced during the drawing process, and the diameter of the finished tube is within strict tolerances. The drawing equipment can be operated continuously or discontinuously. During the drawing process, the workpiece is clamped to the side of the drawing die by a drive, wherein the finished tube can be clamped. In order to continuously draw the tube, in one embodiment, the drawing apparatus requires at least two drawing drives to alternately clamp the tube so as to continuously draw the tube through the drawing die.

[0041] In an embodiment of the invention, after cold forming, the tube is processed by ring tightening or ball tightening.

[0042] After cold forming (eg pilger milling or cold drawing) of the hollow body into a tube, treatment by ring or ball tightening leads to increased yield strength and reduced crack propagation.

[0043] In an embodiment of the invention, after cold forming, in particular after pilger milling or after pilger milling and cold drawing, the tube is annealed in a temperature range of 400° C. to 460° C., wherein during annealing the tube is kept in a controlled atmosphere.

[0044] Tubes manufactured by this method will achieve both high tensile strength and high elongation for high pressure applications.

[0045] In another embodiment of the present invention, the outer diameter of the tube is 40 mm or less and the wall thickness is 1.32 mm or less.

[0046] In yet another embodiment of the present invention, the tube has an outer diameter of 38.1 mm and a wall thickness of 0.8 mm.

[0047] In an embodiment of the present invention, the tube has an outer diameter of 38.1 mm and a wall thickness of 0.6 mm.

[0048] In yet another embodiment of the present invention, the wall thickness of the tube is 0.8 mm or 0.6 mm.

[0049] In aerospace applications and many watercraft, the space available for tubes is small and it is crucial to reduce weight. Therefore, for aerospace applications and watercraft, tubes must be manufactured with thin walls.

[0050] In an embodiment of the invention, the system is used to conduct pressurized liquid hydrogen at a pressure above 100 bar in a conduit.

[0051] In another embodiment of the invention, the system is used to conduct pressurized liquid hydrogen at a pressure above 1000 bar in a conduit.

[0052] Especially for applications where space is limited, compressed liquid hydrogen would result in a significantly higher storage density. An advantage of the invention mentioned is therefore its increased pressure resistance.

[0053] Additionally, at least one of the above aspects is addressed by a method of manufacturing a system for transporting liquid hydrogen, wherein manufacturing a tube forming a conduit of the system comprises the steps of providing a melt of austenitic stainless steel comprising, in weight %, C≤0.040, 8.00≤Mn≤10.00, Si≤1.00, P≤0.030, S≤0.030, 19.00≤Cr≤21.50, 5.50≤Ni≤7.50, 0.15≤N≤0.40, Mo≤0.75, Cu≤0.75, with the remainder being Fe and typically present impurities; extruding a billet from the melt; hot forming the billet into a tubular hollow body; cooling the hollow body; and cold forming the hollow body into a tube.

[0054] By means of the steps of the method according to the invention, a seamless pipe is provided.

[0055] In another embodiment of the present invention, a melt of austenitic stainless steel is provided, wherein the austenitic stainless steel consists of or comprises the same above-mentioned elements but has a maximum content of C ≤ 0.040 in weight %. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Other advantages, features, and applications of the present invention will become apparent from the following description of the embodiments and the corresponding drawings. The foregoing and the following detailed description of the embodiments will be better understood when read in conjunction with the accompanying drawings. It should be understood that the depicted embodiments are not limited to the precise arrangements and instrumentalities shown.

[0057] Figure 1 is a schematic front view of a filling station according to an embodiment of the present invention.

[0058] Figure 2 is a schematic side view of a watercraft according to an embodiment of the present invention.

[0059] Figure 3 is a flow chart of a method according to an embodiment of the present invention.

[0060] Reference numerals

[0061] 1 Filling station

[0062] 2 tubes

[0063] 3 Storage for liquid hydrogen

[0064] 4 pump nozzles

[0065] 5 Water transport

[0066] 6 Fuel Cells

[0067] 100 Provides a molten austenitic stainless steel

[0068] 101 Extrusion of billets from the melt

[0069] 102 Hot rolling the billet into a tubular hollow body

[0070] 103 Cooling Steps

[0071] 104 Pilgrimage Cold Milling Steps

[0072] 105 Cold Drawing Steps DETAILED DESCRIPTION

[0073] Figure 11 is a schematic front view of a filling station 1 according to an embodiment of the present invention, wherein a section of the conduit is provided by a seamless pipe 2 made of 21-6-9 stainless steel. A reservoir 3 for liquid hydrogen is used to extract liquid hydrogen using a pump nozzle 4, which is in fluid communication with the reservoir 3 for liquid hydrogen via the pipe 2.

[0074] Figure 2 2 is a schematic side view of a watercraft 5, more precisely a submarine, according to an embodiment of the present invention, wherein the conduit is provided by a seamless pipe 2 according to an embodiment of the present invention. A reservoir 3 for liquid hydrogen is arranged in the body of the submarine 5, which is in fluid communication with a fuel cell 6 via the pipe 2. The fuel cell 6 is then used to provide fuel for a propulsion system (not shown).

[0075] Figure 3 is used to describe the process of forming a hollow body into Figure 1 and Figure 2 Flowchart of a method for producing a tube 2 used in an application as shown in FIG. In a first step 100, a melt of austenitic stainless steel is provided, wherein the austenitic stainless steel comprises, by weight: C≤0.080, 8.00≤Mn≤10.00, Si≤1.00, P≤0.030, S≤0.030, 19.00≤Cr≤21.50, 5.50≤Ni≤7.50, 0.15≤N≤0.40, Mo≤0.75, Cu≤0.75, the remainder being Fe and typically present impurities.

[0076] After the billet is extruded from the melt in the second step 101, it is hot rolled into a tubular hollow body in step 102. The hollow body is then cooled to room temperature in step 103. In the penultimate step 104, the hollow body is cold-milled by pilgering into a tube as described in the specification. Finally, in step 105, the tube is cold-drawn.

[0077] For the purpose of original disclosure, it should be noted that even if all features are described only with reference to certain other features, all features will become obvious to a person skilled in the art from the present description, drawings and claims, and all features can be combined with themselves or with other features or groups of features disclosed herein in any combination, as long as such combinations are not explicitly excluded or technical facts do not exclude such combinations or render them useless. In order to provide a brief and readable description, a comprehensive and clear description of every possible combination of features has simply been omitted.

[0078] Although the invention has been shown in detail in the drawings and the foregoing description, this description is by way of example only and should not be considered limiting of the scope of protection, as defined by the claims.The invention is not limited to the disclosed embodiments.

[0079] Variations of the disclosed embodiments will be apparent to those skilled in the art from the drawings, the description, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain features are claimed in different claims does not exclude a combination of these features. Reference signs in the claims should not be construed as limiting the scope of protection.

Claims

1. A system for transporting liquid hydrogen, the system comprising: Liquid hydrogen transmission equipment; Liquid hydrogen receiving equipment; and a conduit in fluid communication with the liquid hydrogen transmission device and the liquid hydrogen receiving device, for guiding liquid hydrogen between the liquid hydrogen transmission device and the liquid hydrogen receiving device, It is characterized by: At least one section of the conduit is provided by a seamless tube (2) made of austenitic stainless steel comprising, in wt. %: C≤0.080， 8.00≤Mn≤10.00, Si≤1.00, P≤0.030， S≤0.030， 19.00≤Cr≤21.50， 5.50≤Ni≤7.50, 0.15≤N≤0.40， Mo≤0.75, Cu≤0.75, The rest is Fe and commonly present impurities, The system is for guiding liquid hydrogen pressurized at a pressure above 100 bar in the conduit, wherein the outer diameter of the seamless pipe (2) is less than 40 mm and the wall thickness is less than 1.32 mm, The seamless pipe (2) is obtained by a method comprising the following steps: providing a melt (100) of the austenitic stainless steel, extruding a billet (101) from the melt; hot forming the blank into a tubular hollow body (102); Cooling the hollow body (103); and The hollow body is cold formed (104, 105) into the seamless tube (2).

2. The system according to claim 1, wherein the system is a filling station (1), wherein the liquid hydrogen transmission device is a storage container (3) for liquid hydrogen, and wherein the liquid hydrogen receiving device is a pump nozzle (4).

3. The system according to claim 1, wherein the system is a vehicle, an air vehicle or a water vehicle (5), wherein the liquid hydrogen transmission device is a storage (3) for liquid hydrogen, and wherein the liquid hydrogen receiving device is a hydrogen engine or a fuel cell (6).

4. The system according to claim 1, wherein the cold forming is pilger cold milling (104) or cold drawing (105).

5. The system according to claim 4, wherein the seamless tube (2) is cold formed by pilger milling (104), and after the pilger milling (104), the seamless tube (2) is cold drawn (105) by a drawing die.

6. System according to claim 4, wherein after cold forming (104, 105), the seamless tube (2) is processed by ring tightening or ball tightening.

7. The system according to claim 4, wherein after cold forming (104, 105), the seamless tube (2) is annealed in a temperature range of 400°C to 460°C, wherein during annealing, the seamless tube (2) is kept in a controlled atmosphere.

8. Use of the system according to any one of claims 1 to 7 for guiding pressurized liquid hydrogen at a pressure above 100 bar in the conduit.

9. A method for manufacturing a system for transporting liquid hydrogen according to claim 1, wherein manufacturing a seamless pipe (2) forming a conduit of the system comprises the following steps: A melt (100) of austenitic stainless steel is provided, the austenitic stainless steel comprising, in wt. %: C≤0.080， 8.00≤Mn≤10.00, Si≤1.00, P≤0.030， S≤0.030， 19.00≤Cr≤21.50， 5.50≤Ni≤7.50, 0.15≤N≤0.40， Mo≤0.75, Cu≤0.75, The rest is Fe and commonly present impurities; extruding a billet (101) from the melt; hot forming the blank into a tubular hollow body (102); Cooling the hollow body (103); and The hollow body is cold formed (104, 105) into the seamless tube (2).

10. The method according to claim 9, wherein the cold forming is pilger cold milling (104) or cold drawing (105).

11. The method according to claim 9, wherein the hollow body is cold formed by pilger milling (104), and after the pilger milling (104), the seamless tube (2) is cold drawn (105) by means of a drawing die.

12. The method according to claim 10, wherein after cold forming, the seamless tube (2) is processed by ring tightening or ball tightening.

13. The method of claim 10, wherein after pilger milling (104), the seamless tube (2) is annealed in a temperature range of 400°C to 460°C, wherein during annealing, the seamless tube (2) is kept in a controlled atmosphere.

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