A double-walled cryogenic tank for storing a cryogenic fluid

Abstract

The invention relates to a double-walled cryogenic tank (1) for storing a cryogenic fluid (2). The double-walled cryogenic tank comprises an inner tank (3) containing the cryogenic fluid, an outer tank (4) enclosing the inner tank, and a suspension shell element (6) connecting an outer surface (7) of the inner tank (3) and an inner surface (8) of the outer tank (4). The inner tank (3) is suspended inside the outer tank (4) by the suspension shell element (6). The double-walled cryogenic tank (1) has a cooling system (9) arranged to conduct heat away from the suspension shell element (6) by heat exchange with a cooling medium (10).

Description

[0001] A double-walled cryogenic tank for storing a cryogenic fluid

[0002] TECHNICAL FIELD

[0003] The invention relates to a double-walled cryogenic tank for storing a cryogenic fluid, and a method for cooling a suspension shell element of a double-walled cryogenic tank.

[0004] BACKGROUND

[0005] Cryogenic systems for handling cryogenic fluids, such as cryogenic liquids and gases, usually comprises double-walled vacuum insulated cryogenic tanks for storing cryogenic fluids. Such a cryogenic tank with an inner tank containing the cryogenic fluid and an outer tank enclosing the inner tank, usually has some kind of suspension device which positions the inner tank and the outer tank relative to each other and provides the desired distance between the inner tank and the outer tank, i.e. between the walls of the cryogenic tank.

[0006] A drawback associated with a double-walled cryogenic tank is that heat will be transferred from outside the cryogenic tank into the inner tank and to the cryogenic fluid via the suspension device which mechanically connects the inner tank and the outer tank to each other.

[0007] SUMMARY

[0008] An objective of the invention is to provide a double-walled cryogenic tank for storing a cryogenic fluid, by which double-walled cryogenic tank the heat transferred to the inner tank can be reduced in a non-complicated way, at the same time as a suspension device can be designed for carrying loads in a robust way.

[0009] The objective is achieved by a double-walled cryogenic tank for storing a cryogenic fluid, wherein the double-walled cryogenic tank comprises an inner tank containing the cryogenic fluid, an outer tank enclosing the inner tank, and a suspension shell element connecting an outer surface of the inner tank and an inner surface of the outer tank, and wherein the inner tank is suspended inside the outer tank by the suspension shell element, and the double-walled cryogenic tank has a cooling system arranged to conduct heat away from the suspension shell element by heat exchange with a cooling medium. The invention is based on the insight that by such a double-walled cryogenic tank, heat can be counteracted from being transported to the inner tank via the suspension shell element. This means that the rate of heating the cryogenic fluid in the cryogenic tank is reduced, which in turn means a colder cryogenic fluid in the cryogenic tank and lower pressure increase in the cryogenic tank over time.

[0010] By the term “shell element or shell plate” is meant a three-dimensional element having a relatively large extension in two main dimensions with a significant smaller thickness in a third dimension compared to the two main dimensions.

[0011] According to one embodiment, the double-walled cryogenic tank comprises a pipe loop for transporting cryogenic fluid from the inner tank to a consumer of cryogenic fluid, wherein the cooling system comprises the pipe loop having a first pipe portion extending from the inner tank to the suspension shell element, and a second pipe portion extending from the suspension shell element to the consumer, and the cooling medium of the cooling system is cryogenic fluid transported in the pipe loop from the inner tank to the suspension shell element and further to the consumer. Hereby, cooling of the suspension shell element can be performed in an effective and rational way with use of a minimum of additional equipment. When the cryogenic fluid has been used for cooling the suspension shell element, it will be brought to outside the cryogenic tank for consumption, preferably to a low pressure source for consumption in a boiler, heater, combustion engine, fuel cells or similar. Additionally, a further advantage of using cryogenic fluid from the inner tank is that a depressurization effect in the inner tank is achieved which reduces the rate of pressure increase in the inner tank.

[0012] According to a further embodiment of the double-walled cryogenic tank, the pipe loop has an intermediate pipe portion connecting the first pipe portion and the second pipe portion, which intermediate pipe portion extends along a surface of the suspension shell element, and is arranged in contact with the surface of the suspension shell element. Hereby, the heat can be effectively transferred from the suspension shell element to the cooling medium flowing in the intermediate pipe portion.

[0013] According to a further embodiment of the double-walled cryogenic tank, the intermediate pipe portion extends along a circumference of the suspension shell element, preferably at least one turn around the circumference of the suspension shell element, and more preferably the intermediate pipe portion extends a plurality of turns around the circumference of the suspension shell element. Hereby, a rotationally symmetric temperature profile can be achieved in the suspension shell element. In other words; in the circumferential direction, the temperature in the suspension shell element can be held substantially constant, whereas the temperature in the radial direction from the outer tank to the inner tank will vary.

[0014] According to a further embodiment of the double-walled cryogenic tank, the first pipe portion extends from the inner tank to a position outside the outer tank and further from the position outside the outer tank to the suspension shell element inside the outer tank. Hereby, safe control of fluid transport to the suspension shell element in the annular space between the inner tank and the outer tank can be performed.

[0015] According to a further embodiment of the double-walled cryogenic tank, a section of the first pipe portion extending between the inner tank and the outer tank is double-walled, wherein the section of the first pipe portion comprises an inner pipe part for transporting the cryogenic fluid and an outer pipe part enclosing the inner pipe part. Hereby, cryogenic fluid can be collected safely in the outer pipe part in the event of a leakage from the inner pipe part, preventing cryogenic liquid from reaching the annular space between the inner tank and the outer tank.

[0016] According to a further embodiment, the double-walled cryogenic tank has a longitudinal axis and the suspension shell element is axisymmetric with respect to the longitudinal axis. Hereby, the cryogenic tank will have uniform mechanical strength for absorbing loads in all radial directions.

[0017] According to a further embodiment, the double-walled cryogenic tank has an elongated shape extending in the direction of the longitudinal axis, preferably the longitudinal axis is arranged vertically when the double-walled cryogenic tank is installed.

[0018] According to a further embodiment of the double-walled cryogenic tank, the suspension shell element is a truncated hollow cone connecting the inner tank and the outer tank, wherein a first end of the truncated hollow cone is welded to the inner surface of the outer tank and a second end of the truncated hollow cone is welded to the outer surface of the inner tank. Hereby, both vertical and horizontal loads can be carried or absorbed. Further, the truncated hollow cone is rotationally symmetric carrying loads equal in all radial directions.

[0019] According to a further embodiment of the double-walled cryogenic tank, the first end of the truncated hollow cone is arranged above the second end of the truncated hollow cone when the double-walled cryogenic tank is installed.

[0020] According to a further embodiment, the double-walled cryogenic tank has a further suspension shell element which is a disc connecting the outer surface of the inner tank and the inner surface of the outer tank.

[0021] According to a further embodiment of the double-walled cryogenic tank, the disc is arranged in an upper part of the double-walled cryogenic tank and the truncated hollow cone is arranged in a lower part of the double-walled cryogenic tank.

[0022] According to a further embodiment, the double-walled cryogenic tank is a vacuum insulated tank having an annular space between the inner tank and the outer tank which annular space is vacuum pumped. Hereby, the heat conduction from outside the cryogenic tank to the cryogenic fluid inside the inner tank can be significantly reduced.

[0023] The invention also relates to a method for cooling a suspension shell element of a doublewalled cryogenic tank according to claim 1 , comprising conducting heat away from the suspension shell element by heat exchange with a cooling medium, and preferably transporting cryogenic fluid from the inner tank to a consumer of cryogenic fluid, wherein the cooling medium is cryogenic fluid transported from the inner tank to the suspension shell element and further to the consumer.

[0024] The advantages of the method are similar to the advantages already discussed hereinabove with reference to the different embodiments of the double-walled cryogenic tank.

[0025] Further advantages and advantageous features of the invention are disclosed in the following description and in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

[0027] In the drawings:

[0028] Fig. 1A shows a cryogenic tank,

[0029] Fig. 1B is a cut view of the cryogenic tank illustrated in Fig. 1A,

[0030] Fig. 2 is a variant of the cryogenic tank, and

[0031] Fig. 3 shows in a perspective view one embodiment of a suspension shell element of the cryogenic tank.

[0032] DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0033] Figs. 1A and 1B show a double-walled cryogenic tank 1 for storing a cryogenic fluid 2. The double-walled cryogenic tank 1 comprises an inner tank 3 containing the cryogenic fluid 2 and an outer tank 4 enclosing the inner tank 3. The double-walled cryogenic tank 1 is preferably a vacuum insulated tank having an annular space 5 between the inner tank 3 and the outer tank 4 which annular space 5 is vacuum pumped. The inner tank 3 is suitably a pressure vessel such as an independent Type C tank, and the outer tank 4 forms a vacuum jacket or second barrier. The annular space 5 can be filled by any suitable bulk material, such as traditional multilayer insulation or fine distributed granules.

[0034] The double-walled cryogenic tank 1 further comprises a suspension shell element 6 connecting an outer surface 7 of the inner tank 3 and an inner surface 8 of the outer tank 4 to each other, whereby the inner tank 3 is suspended from the outer tank 4 inside the outer tank 4 by the suspension shell element 6. The double-walled cryogenic tank 1 has a cooling system 9 arranged to conduct heat away from the suspension shell element 6 by heat exchange with a cooling medium 10. The double-walled cryogenic tank 1 can have an elongated shape extending in the direction of a longitudinal axis 22, preferably a center axis of the double-walled cryogenic tank 1, and the suspension shell element 6 is suitably axisymmetric with respect to the longitudinal axis 22. The double-walled cryogenic tank 1 is suitably a vertical tank, i.e. the longitudinal axis 22 is arranged vertically when the double-walled cryogenic tank 1 is installed properly for operation.

[0035] In the example embodiment illustrated in Figs. 1A and 1 B, the double-walled cryogenic tank 1 comprises a pipe loop 11 for transporting cryogenic fluid 2 from the inner tank 3 to a consumer (not illustrated) of cryogenic fluid. Further, the cooling system 9 comprises the pipe loop 11 having a first pipe portion 12 extending from the inner tank 3 to the suspension shell element 6, and a second pipe portion 13 extending from the suspension shell element 6 to the consumer. The cooling medium 10 of the cooling system 9 is cryogenic fluid 2 transported in the pipe loop 11 from the inner tank 3 to the suspension shell element 6 and further to the consumer. An arrow 14 to the left in Figs. 1A and 1 B, indicates the flow direction of the cryogenic fluid 2 to the consumer. The flow direction in the first pipe portion 12 is indicated by an arrow 31, and the flow direction in the second pipe portion 13 is indicated by an arrow 32.

[0036] The pipe loop 11 has suitably an intermediate pipe portion 15 connecting the first pipe portion 12 and the second pipe portion 13 to each other, which intermediate pipe portion 15 extends along a surface 16 of the suspension shell element 6, and is arranged in contact with the surface 16 of the suspension shell element 6. Se also Fig. 3.

[0037] As also appears from Fig. 3, the intermediate pipe portion 15 suitably extends along a circumference of the suspension shell element 6, preferably at least one turn around the circumference of the suspension shell element 6. More preferably, the intermediate pipe portion 15 extends a plurality of turns around the circumference of the suspension shell element 6, as illustrated in Fig. 3. The intermediate pipe portion 15 is suitably attached to the suspension shell element 6 by welding. Such a weld 17 can be designed in many ways known by the skilled person. Further, the number of turns and the pipe dimension of the intermediate pipe portion 15, can be varied depending on various parameters such as a size of a surface 16 or volume of the suspension shell element 6 to be cooled, a flow rate of the cooling medium 10 inside the intermediate pipe portion 15, etc. In the example embodiment illustrated in Fig. 3, the suspension shell element 6 is a truncated hollow cone, preferably a right circular cone, connecting the inner tank 3 and the outer tank 4. A first end 25 of the truncated hollow cone 6 is welded to the inner surface 8 of the outer tank 4 and a second end 26 of the truncated hollow cone 6 is welded to the outer surface 7 of the inner tank 3. Although it could be the other way around, in Fig. 1 B, the first end 25 of the truncated hollow cone 6 is arranged above the second end 26 of the truncated hollow cone 6 when the double-walled cryogenic tank 1 is installed properly. The truncated hollow cone 6 is suitably arranged in a lower part of the of the double-walled cryogenic tank 1.

[0038] In Fig. 3, an enlarged cut view is also showing a cross section of the intermediate pipe portion 15 in which the cooling medium 10 is to flow, and the weld 17 by which the intermediate pipe portion 15 is attached to the surface 16 of the suspension shell element 6. Heat exchange between the cooling medium 10 and the suspension shell element 6 will take place when the cooling medium 10 flows in the intermediate pipe portion 15, i.e. heat will be conducted away from the suspension shell element 6 to the cooling medium 10.

[0039] As further illustrated in Fig. 1 B, the first pipe portion 12 suitably extends from the inner tank 3 to a position 18 outside the outer tank 4 and further from the position 18 outside the outer tank 4 to the suspension shell element 6 inside the outer tank 4. A section 19 of the first pipe portion 12 extending between the inner tank 3 and the outer tank 4 is preferably double-walled, wherein the section 19 of the first pipe portion 12 comprises an inner pipe part 20 for transporting the cryogenic fluid 2 and an outer pipe part 21 enclosing the inner pipe part 20. For the other part of the first pipe portion 12 extending from the outside of the outer tank 4 into the annular space 5 and to the suspension shell element 6, which other pipe part does not need to be double-walled, any leak can be stopped by closing a valve at the top of the double-walled cryogenic tank 1.

[0040] The pipe loop 11 can comprise an outlet 23 from the inner tank 3 arranged relatively low, close to the bottom of the double-walled cryogenic tank 1 , for transportation of cryogenic fluid in the form of liquid, and / or an outlet 24 from the inner tank 3 arranged relatively high, close to the top of the double-walled cryogenic tank 1, for transportation of cryogenic fluid in the form of gas. In the example embodiment illustrated in Figs. 1A and 1 B, the double-walled cryogenic tank 1 has one Emergency Shut Down (ESD) valve 27, 28 arranged outside the outer tank 4 for each outlet 23, 24. Such an EDS valve is designed to stop the flow of cryogenic fluid upon detection of a potentially dangerous event. Further, a block valve or shutoff valve 29 is arranged in the first pipe portion 12 of the pipe loop 11. When the block valve 29 is open cryogenic fluid can flow from the double-walled cryogenic tank 1 to the consumer, and when the block valve 29 is closed, the flow of cryogenic fluid from the double-walled cryogenic tank 1 to the consumer is stopped. A control valve 30 is arranged in the second pipe portion 13 of the pipe loop 11 for controlling the flow of cryogenic fluid from the double-walled cryogenic tank 1 to the consumer when the block valve 29 is open.

[0041] In addition, the double-walled cryogenic tank 1 can comprise a further suspension shell element 6b which can be a disc or membrane connecting the outer surface 7 of the inner tank 3 and the inner surface 8 of the outer tank 4 to each other. The disc 6b can be arranged in an upper part of the double-walled cryogenic tank 1 and the truncated hollow cone 6 can be arranged in a lower part of the double-walled cryogenic tank 1, as illustrated in Fig. 1B. In the same way as previously described for the truncated hollow cone 6, the disc 6b can be arranged such that the inner tank 3 is suspended from the outer tank 4 inside the outer tank 4 by the disc 6b.

[0042] Further, the disc 6b can also be cooled by the cooling system 9. In the example embodiment illustrated in Fig. 1 B, the pipe loop 11 also has a further first pipe portion 12b extending from the inner tank 3 to the disc 6b, and a further second pipe portion 13b extending from the disc 6b to the consumer. The pipe loop 11 has suitably a further intermediate pipe portion 15b connecting the further first pipe portion 12b and the further second pipe portion 13b to each other, which further intermediate pipe portion 15b extends along a surface 16b of the disc 6b, and is arranged in contact with the surface 16b of the disc 6b for heat exchange between the disc 6b and the cooling medium 10 flowing in the further intermediate pipe portion 15b. In addition, a further block valve 29b and a further control valve 30b, can be correspondingly arranged in the further first pipe portion 12b and the further second pipe portion 13b, respectively. The further block valve 29b and the further control valve 30b are of the same type and have the same function as previously described with respect to the block valve 29 and the control valve 30. Fig. 2 shows in a cut view a variant of the double-walled cryogenic tank T for storing a cryogenic fluid 2. For features not discussed hereinbelow, reference is made to the example embodiment illustrated in Figs. 1A and 1B. In the example embodiment illustrated in Fig. 2, the cooling medium 10’ of the cooling system 9’ is different from the cryogenic fluid 2 of the double-walled cryogenic tank T. The cooling medium 10’ used for heat exchange with the suspension shell element 6’ is brought from another source (not shown), such as for example another cryogenic tank. The cooling medium enters a pipe portion 15’ of the suspension shell element 6’, see arrow 3T, circulates through the pipe portion 15’, and leaves the pipe portion 15’, see arrow 32’. As it regards the details of the suspension shell element 6’ and the pipe portion 15’, see suspension shell element 6 and intermediate pipe portion 15 in Fig. 3. The cryogenic fluid 2 of the inner tank 3 can be transported via the liquid outlet 23 or the gas outlet 24 from the inner tank 3 to a consumer of the cryogenic fluid as indicated by the arrow 14. It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Claims

AMENDED CLAIMS received by the International Bureau on 18 February 2025 (18.02.2025)1. A double-walled cryogenic tank (1) for storing a cryogenic fluid (2), the double-walled cryogenic tank comprising an inner tank (3) containing the cryogenic fluid, an outer tank (4) enclosing the inner tank, and a suspension shell element (6) connecting an outer surface (7) of the inner tank (3) and an inner surface (8) of the outer tank (4), the inner tank (3) being suspended inside the outer tank (4) by the suspension shell element (6), wherein the double-walled cryogenic tank (1) has a cooling system (9) arranged to conduct heat away from the suspension shell element (6) by heat exchange with a cooling medium (10), and the double-walled cryogenic tank (1) comprises a pipe loop (11) for transporting cryogenic fluid (2) from the inner tank (3) to a consumer of cryogenic fluid, the cooling system (9) comprising the pipe loop (11) having a first pipe portion (12) extending from the inner tank to the suspension shell element, and a second pipe portion (13) extending from the suspension shell element to the consumer, the cooling medium (10) of the cooling system (9) being cryogenic fluid (2) transported in the pipe loop (11) from the inner tank (3) to the suspension shell element (6) and further to the consumer, and wherein the first pipe portion (12) extends from the inner tank (3) to a position (18) outside the outer tank (4) and further from the position outside the outer tank to the suspension shell element (6) inside the outer tank (4).

2. A double-walled cryogenic tank according to claim 1 , characterized in that the pipe loop (11) has an intermediate pipe portion (15) connecting the first pipe portion (12) and the second pipe portion (13), which intermediate pipe portion (15) extends along a surface (16) of the suspension shell element (6), and is arranged in contact with the surface (16) of the suspension shell element (6).

3. A double-walled cryogenic tank according to claim 2, characterized in that the intermediate pipe portion (15) extends along a circumference of the suspension shell element (6), preferably at least one turn around the circumference of the suspension shell element (6).

4. A double-walled cryogenic tank according to claim 3, characterized in that the intermediate pipe portion (15) extends a plurality of turns around the circumference of the suspension shell element (6).

5. A double-walled cryogenic tank according to any of claims claim 1-4, characterized in that a section (19) of the first pipe portion (12) extending between the inner tank (3) and the outer tank (4) is double-walled, wherein the section (1) of the first pipe portion (12) comprises an inner pipe part (20) for transporting the cryogenic fluid and an outer pipe part (21) enclosing the inner pipe part (20).

6. A double-walled cryogenic tank according to any preceding claim, characterized in that the double-walled cryogenic tank (1) has a longitudinal axis (22) and the suspension shell element (6) is axisymmetric with respect to the longitudinal axis (22).

7. A double-walled cryogenic tank according to claim 6, characterized in that the double-walled cryogenic tank (1) has an elongated shape extending in the direction of the longitudinal axis (22).

8. A double-walled cryogenic tank according to claim 6 or 7, characterized in that the longitudinal axis (22) is arranged vertically when the double-walled cryogenic tank (1) is installed.

9. A double-walled cryogenic tank according to any preceding claim, characterized in that the suspension shell element (6) is a truncated hollow cone connecting the inner tank (3) and the outer tank (4), wherein a first end (25) of the truncated hollow cone (6) is welded to the inner surface (8) of the outer tank (4) and a second end (26) of the truncated hollow cone (6) is welded to the outer surface (7) of the inner tank (3).

10. A double-walled cryogenic tank according to claim 9, characterized in that the first end (25) of the truncated hollow cone (6) is arranged above thesecond end (26) of the truncated hollow cone (6) when the double-walled cryogenic tank (1) is installed.

11. A double-walled cryogenic tank according to any preceding claim, characterized in that the double-walled cryogenic tank (1) has a further suspension shell element (6) which is a disc (6b) connecting the outer surface (7) of the inner tank (3) and the inner surface (8) of the outer tank (4).

12. A double-walled cryogenic tank according to any of claims 9-10 and claim 11 , characterized in that the disc (6b) is arranged in an upper part of the double-walled cryogenic tank (1) and the truncated hollow cone (6) is arranged in a lower part of the double-walled cryogenic tank (1).

13. A double-walled cryogenic tank according to any preceding claim, characterized in that the double-walled cryogenic tank (1) is a vacuum insulated tank having an annular space (5) between the inner tank (3) and the outer tank (4) which annular space is vacuum pumped.

14. A method for cooling a shell element of a double-walled cryogenic tank (1) according to claim 1 , comprising conducting heat away from the suspension shell element (6) by heat exchange with a cooling medium (10), and transporting cryogenic fluid (2) from the inner tank (3) to a consumer of cryogenic fluid, the cooling medium (10) being cryogenic fluid (2) transported from the inner tank (3) to the suspension shell element (6) in the first pipe portion (12) and further to the consumer.

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