APPARATUS FOR TRANSMITTING ELECTRICAL ENERGY WITH A SUPERCONDUCTING CURRENT CARRIER

Abstract

Apparatus for transmitting electrical energy with a superconducting current carrier, in which the superconducting current carrier to be cooled is accommodated in a first cooling channel, which first cooling channel is connected by way of a coolant feed line to a supply device for a first cooling medium and is surrounded by at least one second cooling channel, for conducting through a second cooling medium, which is flow-connected to a coolant-discharge line for heated second cooling medium, wherein a supercooled, liquefied gas is used as the first cooling medium, is characterized according to the invention in that a liquefied gas is used as the second cooling medium and the second cooling channel is equipped with means for removing a gas phase occurring due to evaporation of the second cooling medium.

Claims

1. An apparatus for transmitting electrical energy with a superconducting current carrier, in which the current carrier to be cooled is accommodated in a first cooling channel, which first cooling channel is connected by way of a coolant feed line to a supply device for a first cooling medium and is equipped with a heat shield, which surrounds the first cooling channel and is thermally connected to at least one second cooling channel, through which a second cooling medium flows, wherein a supercooled, liquefied gas is used as the first cooling medium, wherein a liquefied gas is used as the second cooling medium and the at least one second cooling channel is equipped with at least one gas phase separator.

2. The apparatus according to claim 1, wherein the gas phase separator comprises a container which is flow-connected to the second cooling channel and the geodetically upper portion of which is flow-connected to an exhaust-gas line for removing the gas phase.

3. The apparatus according to claim 1, wherein the gas phase is discharged in the gas phase separator by way of a float valve, a fitting or a liquid-tight, but gas-permeable membrane.

4. The apparatus according to claim 1, wherein supercooled second cooling medium is used as the first cooling medium.

5. The apparatus according to claim 1, wherein between the first cooling channel and at least one second cooling channel, at least one flow connection is provided for introducing cooling medium from the first cooling channel into at least one second cooling channel.

6. The apparatus according to claim 5, wherein at least one flow connection between the first cooling channel and at least one second cooling channel is arranged in the region of a head portion of the apparatus that is at a distance from the coolant feed line of the first cooling channel.

7. The apparatus according to claim 5, wherein between the first cooling channel and at least one second cooling channel, a plurality of flow connections are provided, arranged at a distance from one another in the longitudinal direction of the cooling channels.

8. The apparatus according to claim 5, wherein the flow connection between the first cooling channel and at least one second cooling channel is equipped with fittings for controlling the through-flow of cooling medium.

9. An arrangement for transmitting electrical energy with a superconducting current carrier in which a plurality of apparatuses according to claim 1 are connected to one another.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Exemplary embodiments of the invention are to be explained more specifically on the basis of the drawing, in which schematically:

[0031] FIG. 1 shows the detail of an apparatus according to the invention in a first embodiment in longitudinal section,

[0032] FIG. 2 shows the detail of an apparatus according to the invention in another embodiment in longitudinal section,

[0033] FIG. 3 shows the apparatus from FIG. 2 in cross section along the sectional line III-III in FIG. 1, and

[0034] FIG. 4 shows an apparatus according to the invention in a further embodiment in cross section.

DETAILED DESCRIPTION

[0035] The apparatus 1 shown in FIG. 1 comprises a superconducting current carrier, which in the exemplary embodiments shown here is a superconducting cable 2 or at least a section of a superconducting current carrier 2, which is accommodated in a cooling arrangement 3 for cooling the superconductor 2. The cooling arrangement 3 has a tubular or box-shaped housing 4, which has for example a length of several hundred metres to several kilometres and ends at head portions 5, 6 at both ends.

[0036] The superconducting cable 2 is arranged substantially along the axis of the housing 3. Surrounding it, for example coaxially in relation to the superconducting cable 2, runs a first tubular or box-shaped cooling channel 7 and surrounding it, for example coaxially in relation to it, is a second tubular or box-shaped cooling channel 8, which cooling channels are separated from one another by a casing 9 of a material with good thermal insulation. In the region of the head portions 5, 6, the cooling channels 7, 8 are connected to one another in terms of flow at lead-throughs 11a, 11b; 12a, 12b; otherwise, in the exemplary embodiment shown in FIG. 1, there is no flow connection between the cooling channels 7, 8.

[0037] Arranged radially outside on the second cooling channel 8 is a gas discharge channel 13, which in turn is enclosed by a thermal insulation, for example a vacuum insulation 14. There is no flow connection between the second cooling channel 8 and the gas discharge channel 13, with the exception of a flow connection in the region of a gas phase separator 15 described more specifically below. The gas discharge channel 13 is flow-connected to an exhaust-gas line 16, which in the exemplary embodiment is provided in the region of a head portion, here the head portion 5.

[0038] The apparatus 1 also has a coolant feed line 17, which establishes a flow connection between a cooling device 18 and the first cooling channel 7. The cooling device 18 is for example a supercooler for supercooling a liquefied cryogenic medium, for example liquid nitrogen. The cooling device 18 is also flow-connected by way of a return line 19 to the second cooling channel 8. Furthermore, the cooling device 18 is connected to a storage container 20, from which fresh cooling medium can be supplied if and when required during the operation of the apparatus 1.

[0039] The gas phase separator 15 is arranged at an upper part—seen geodetically—of the housing 3 and comprises a container 21, which is flow-connected by way of a feed line 22 and a return line 23 to the second cooling channel 8. Furthermore, a gas line 23, which opens into the gas discharge channel 13, opens out from an upper portion of the container 21.

[0040] The apparatus 1 is part of an overall arrangement for transmitting electrical energy. In the exemplary embodiment shown here, the head portion 6 is adjoined by an identical apparatus 25, which is only indicated here, the superconducting cable 2 being led through terminating walls 26, 27 at the ends of both apparatuses 1, 25. Instead of an apparatus 25, other electrical elements may however also adjoin the head portions 5, 6, as shown here by way of example in the region of the head portion 5. There, the superconducting cable 2 is led through a terminating end wall 28 and is connected to an electrical element 29, which may be for example an electrical load or a power lead or likewise an apparatus according to the invention.

[0041] During the operation of the apparatus 1, the superconducting cable 2 is cooled with a supercooled liquefied gas, for example supercooled nitrogen, supercooled LNG, supercooled liquefied oxygen or a supercooled liquefied noble gas. For this purpose, the cooling medium is taken from the storage container 20, in the cooling device 18 is brought to a temperature below its boiling point, that is to say supercooled, and is fed into the first cooling channel 7 by way of the coolant feed line 17 by means of a feeding device not shown here, for instance a pump. The cooling medium passes through the cooling channel 7 in both directions up to the head portions 5, 6 at a temperature at which the superconducting conductor elements of the superconducting cable 2 are in the superconducting state. In the region of the head portions 5, 6, the cooling medium flows into the second cooling channel 8, passes through it from both head portions 5, 6 and flows into the return line 19, through which in the exemplary embodiment shown here it is fed to the cooling device 18, cooled there and fed once again into the first cooling channel 7. If the coolant feed line 17 is in the region of a head portion 5, 6, the cooling medium only flows through the first cooling channel 7 in the direction of the other head portion 6, 5.

[0042] The cooling medium in the second cooling channel 8 serves as a heat shield against the penetration of heat from the surroundings. The heat input causes an increase in the temperature of the cooling medium in the cooling channel 8 up to its boiling temperature and it finally partly evaporates. Therefore, in the second cooling channel 8, the cooling medium takes the form of a phase mixture made up of liquid and gaseous constituents. The gas phase contained in the cooling medium is separated off from the liquid phase in the gas phase separator 15. While the liquid phase is returned to the cooling device 18, the separated-off gas phase passes through the gas discharge channel 13 and finally escapes by way of the exhaust-gas line 16. In an alternative configuration, there is no gas discharge channel 13 and the gas phase is conducted out of the gas phase separator 15 directly into the surrounding atmosphere. Passing the gaseous cooling medium through the gas discharge channel 13 has the effect that the shielding from heat input from outside is further improved. The gaseous cooling medium is finally let out into the surrounding atmosphere or is passed on for some other use. Accordingly, part of the cooling medium circulated by way of the cooling channels 7, 8 and the cooling device 18 is lost and must be replaced by fresh cooling medium from the storage tank 20.

[0043] Instead of the coaxial arrangement of the first cooling channel 7 and the second cooling channel 8 shown here, a construction made of a material with good heat conduction, which is arranged around the first cooling channel 7, for example in the form of a tube casing arranged around the first cooling channel 7, may otherwise be provided as a heat shield. In this case, the second cooling channel is configured as a line which runs parallel to the first cooling channel within the vacuum insulation 14 and is thermally connected to the construction mentioned; in this case, a number of second cooling channels that are thermally connected to the construction may also be used within the vacuum insulation 14.

[0044] The apparatus 101 shown in FIGS. 2 and 3 likewise has a housing 103 with a first cooling channel 107, coaxially enclosing a superconducting current carrier such as for example a superconducting cable 102, and a second cooling channel 108, arranged coaxially around the inner cooling channel 107, which cooling channels are separated from one another by a casing 109 of a material with good thermal insulation and surrounded by a vacuum insulation 114. In the exemplary embodiment shown in FIG. 2, provided between the cooling channel 108 and the gas discharge channel 116 in terms of flow are a plurality of gas phase separators, arranged at a distance from one another along the cooling channel 108, of which however only one gas phase separator 115 is shown here. The gas phase separator 115 is equipped with an exhaust-gas line for removing the gas phase separated off in the gas phase separator 115.

[0045] As a difference from the apparatus 1, however, there is not a flow connection between the cooling channels 7, 8 in the region of the head portions of the housing 103, but by way of lead-throughs 116a, 116b, 116c in the casing 109 arranged at a distance from one another in the longitudinal direction of the housing 103, for example at a distance of 100 m to 1000 m; otherwise, the apparatus 101 is constructed identically to the apparatus 1.

[0046] During the operation of the apparatus 101, cooling medium flows out of a coolant feed, not shown here, in the direction of the arrow through the cooling channel 107 and cools the superconducting cable 102. In this case, a small partial stream of the cooling medium respectively flows off into the cooling channel 108 through the lead-throughs 116a, 116b, 116c. As a result, the mass flow of the cooling medium flowing through the cooling channel 107 decreases with increasing distance from the coolant feed, and the flow rate and the heat input caused by friction on the inner wall of the casing 9 decrease.

[0047] The cooling medium flows through the second cooling channel 108 in the direction of a coolant discharge line not shown here. As it does so, it takes up heat from the surroundings and partially evaporates, that is to say within the second cooling channel 108 therefore takes the form of a phase mixture made up of liquid and gaseous constituents. The gas phase contained in the cooling medium is separated off from the still liquid cooling medium in the way described above in a plurality of gas phase separators 115, which are arranged at regular intervals on the cooling channel 108, and the gas phase separated off from the liquid phase is conducted by way of the exhaust-gas line 113 into the surrounding atmosphere. The still liquid cooling medium is cooled for example in the way described above in a cooling device and is fed once again to the cooling channel 107, but it may also be used in some other way, for example for cooling a non-superconducting power lead (not shown here) connected to the superconducting cable 102.

[0048] The exemplary embodiment shown in FIG. 4 differs from the exemplary embodiment shown in FIG. 3 only in that the flow connections between the cooling channels 107, 108 are not realized by way of simple lead-throughs 116a, 116b, 116c, but instead of a lead-through 116a, 116b, 116c there is a line 117, which by means of a fitting 118 can be controlled on the basis of a prescribed program or in dependence on measured parameters, such as for example the ambient temperature or the temperature of the cooling medium in one of the cooling channels 117, 118.

LIST OF REFERENCE NUMERALS

[0049] 1 Apparatus 25 Apparatus [0050] 2 Superconducting cable 26 Terminating wall [0051] 3 Cooling arrangement 27 Terminating wall [0052] 4 Housing 28 Terminating wall [0053] Head portion 29 Electrical element [0054] 6 Head portion 101 Apparatus [0055] 7 First cooling channel 102 Superconducting cable [0056] 8 Second cooling channel 103 Housing [0057] 9 Casing 104 - [0058] 10 - 105 - [0059] 11a, 11b Lead-through 106 - [0060] 12a, 12b Lead-through 107 First cooling channel [0061] 13 Gas discharge channel 108 Second cooling channel [0062] 14 Vacuum insulation 109 Casing [0063] 15 Gas phase separator 110 - [0064] 16 Exhaust-gas line 111 - [0065] 17 Coolant feed line 112 - [0066] 18 Cooling device 113 Exhaust-gas line [0067] 19 Return line 114 Vacuum insulation [0068] 20 Storage container 115 Gas phase separator [0069] 21 Container 116a, 116b, 116c Lead-throughs [0070] 22 Feed line 117 Line [0071] 23 Return line 118 Fitting [0072] 24 Gas line