Cooling system for superconducting cable

Abstract

To effectively utilize a refrigerant used in a cooling system in a vaporization process of a gas 11 in a liquid state stored in a tank 10 when a gas utilization facility and the cooling system of a superconducting cable are combined.SOLUTION: The superconducting cable cooling system includes at least a tank 10 that stores gas in a liquid state, a heat exchanger 20 having at least a vaporization line 21 and a liquefaction line 22 that can exchange heat with each other, a subcooler 30 that cools a second refrigerant to be circulated to a superconducting cable A with a first refrigerant 31 in a liquid state, a pump 40 that a first refrigerant 32 in a gas state vaporized in the subcooler 30, a heater 50 that is interposed between the subcooler 30 and the pump 40 and heats the first refrigerant 32 in a gas state, and a compressor 60 that pressurizes the heated first refrigerant 32 in a gas state. The vaporization line 21 vaporizes the gas 11 in a liquid state from the tank 10 and supplies it to a gas utilization facility, and the liquefaction line 22 liquefies the first refrigerant 32 in a gas state pressurized by the compressor 60 and supplies it to the sub-cooler 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cooling system for a superconducting cable to be used in combination with a facility that uses gas, and more particularly to a cooling system for a superconducting cable that is suitable for use in combination with a facility that uses high-purity gas. [Background technology]

[0002] Various gases (nitrogen, helium, hydrogen, argon, etc.) are used in various facilities installed in manufacturing plants, research institutes, medical facilities, and various types of mobility (airplanes, passenger cars, ships, etc.). These gases are generally stored in a liquefied state and vaporized as needed for use.

[0003] On the other hand, as a means of supplying power to these facilities, the adoption of superconducting cables equipped with a subcooling system (see Patent Document 1 below) is being considered. The applicant has therefore discovered that there is potential for reusing gas originating from the refrigerant (one refrigerant) used to cool the superconducting cable in a subcooling system as gas for use in these facilities. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-117026 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when gas derived from the other refrigerant is extracted from the subcooler using a pump, impurities may be mixed into the gas that has passed through the pump. Therefore, when high purity is required for the gas used in these facilities, the gas extracted by the pump cannot be supplied to the facilities as is.

[0006] Therefore, an object of the present invention is to provide a means for effectively utilizing the gas extracted from a cooling system when gas utilization equipment is combined with a cooling system for a superconducting cable. [Means for solving the problem]

[0007] The present invention, which has been made to solve the above-mentioned problems, is a cooling system for a superconducting cable to be used in combination with a gas utilization facility, comprising at least a tank for storing the gas in a liquid state, a heat exchanger having at least a vaporization line and a liquefaction line capable of exchanging heat with each other, a subcooler that stores a first refrigerant in a liquid state and uses the first refrigerant in a liquid state to cool a second refrigerant to be circulated within the superconducting cable, a pump that sucks the first refrigerant in a gaseous state vaporized in the subcooler, a heater interposed between the subcooler and the pump and that heats the first refrigerant in a gaseous state, and a compressor that pressurizes the first refrigerant in a gaseous state heated by the heater, wherein the vaporization line is configured to vaporize the liquid gas sent from the tank and supply it to the facility, and the liquefaction line is configured to liquefy the first refrigerant in a gaseous state pressurized by the compressor and supply it to the subcooler. The present invention can also be used in a state where the first refrigerant and the gas have the same major elements, and the purity of the major elements in the gaseous first refrigerant sent to the liquefaction line is lower than the purity of the major elements in the gaseous gas supplied to the equipment. In addition, the present invention may use nitrogen having a purity of 99.999% or more as the gas in a gaseous state to be supplied to the equipment. In the present invention, nitrogen may be used as the gas, the first refrigerant, and the second refrigerant. [Effects of the Invention]

[0008] According to the present invention, even when a cooling system for a superconducting cable is combined with the utilization facility, the gas extracted from the cooling system can be effectively utilized. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing the overall configuration of a cooling system for a superconducting cable according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Example]

[0011] <1> Overall structure FIG. 1 shows an outline of the overall configuration of a cooling system for a superconducting cable according to the present invention (hereinafter also simply referred to as "the system"). This system is designed to supply power in a superconducting state by cooling the conductors that make up the superconducting cable A with a refrigerant. The present invention contemplates that the system will be used in combination with various facilities (hereinafter simply referred to as "utilization facilities") installed in manufacturing plants, research institutes, medical facilities, various forms of mobility (airplanes, passenger cars, ships, etc.), etc. The system is configured to include at least a tank 10, a heat exchanger 20, a subcooler 30, a pump 40, a heater 50, and a compressor 60. Each part will be described in detail below.

[0012] <2> tank The tank 10 is a member for storing gas in a liquid state to be used in the utilization facility. In the present invention, the configuration of the tank 10 is not particularly limited.

[0013] <2.1> Gas In the present invention, the type of gas stored in the tank 10 is not particularly limited as long as it is a liquefiable gas. Examples of liquefiable gases include nitrogen, helium, hydrogen, and argon. In this embodiment, the tank 10 stores liquid nitrogen.

[0014] <3> Subcooler The subcooler 30 is a member for cooling the refrigerant for cooling the superconducting cable A. In the present invention, the configuration of the subcooler 30 is not particularly limited. In this embodiment, a liquid refrigerant (a first liquid refrigerant 31) is contained inside the subcooler 30, and a pipe is arranged inside the subcooler 30 to carry the refrigerant (a second refrigerant C1 before cooling) used to cool the superconducting cable A. The second refrigerant C1 before cooling is extracted from one of the terminal connection parts B1 connected to both ends of the superconducting cable A, and returned to the other terminal connection part B2 via the subcooler 30, thereby allowing the cooled second refrigerant C2 to circulate within the superconducting cable A.

[0015] <3.1>First refrigerant / second refrigerant The first refrigerant is a refrigerant for cooling the second refrigerant in the subcooler 30 . The second refrigerant is a refrigerant for cooling the conductor in the superconducting cable A. In the present invention, the types of the first and second refrigerants are not particularly limited, but in this example, nitrogen is assumed.

[0016] <4> pump The pump 40 is a member for sucking and extracting the first refrigerant 32 in a gaseous state that has evaporated inside the subcooler 30 from the subcooler 30 . In the present invention, the configuration of the pump 40 is not particularly limited. In this embodiment, a vacuum pump is used as the pump 40 .

[0017] <5> Warmer The heater 50 is a member for heating the first refrigerant 32 in a gaseous state sucked by the pump 40 . In the present invention, the configuration of the heater 50 is not particularly limited. In this embodiment, the heater 50 is interposed between the pump 40 and the subcooler 30. This is because the first refrigerant 32 in a gaseous state in the subcooler 30 is at a low temperature, and if it is allowed to flow directly into the pump 40, it may cause a malfunction of the pump 40.

[0018] <6> Compressor The compressor 60 is a member for compressing the first refrigerant 32 in a gaseous state. In the present invention, the configuration of the compressor 60 is not particularly limited. In this embodiment, a compressor is interposed between the pump 40 and the heat exchanger 20, and the pressure of the first refrigerant 32 in a gaseous state is returned to normal pressure before being introduced into the heat exchanger 20. This is because the pressure of the gaseous first refrigerant 32 sucked by the vacuum pump 40 is increased to lower the melting point, thereby accelerating the liquefaction of the first refrigerant in the heat exchanger 20 .

[0019] <7> heat exchanger The heat exchanger 20 is a member for supplying the gas 12 in a gaseous state to the utilization facility and for supplying the first refrigerant 31 in a liquid state to the subcooler 30 . The heat exchanger 20 according to the present invention is configured to have at least a vaporization line 21 and a liquefaction line 22. Each line will be described in detail below.

[0020] <7.1> Vaporization line The vaporization line 21 is a line for vaporizing the liquid gas 11 stored in the tank 10 to generate the gaseous gas 12. The gaseous gas 12 generated by the vaporization line 21 is supplied to a gas utilization facility. In the present invention, the configuration of the vaporization line 21 is not particularly limited.

[0021] <7.2> Liquefaction line The liquefaction line 22 is a line for liquefying the first refrigerant 32 in a gaseous state compressed by the compressor 60. The first refrigerant 31 in a liquid state liquefied by the liquefaction line 22 is configured to be returned to the subcooler 30. In the present invention, the configuration of the liquefaction line 22 is not particularly limited.

[0022] <7.3> Heat exchange between lines In the present invention, the vaporization line 21 and the liquefaction line 22 are configured to be able to exchange heat with each other. By adopting this configuration, the efficiency of generating gaseous gas 12 can be improved by the amount of heat absorbed from liquefaction line 22 in vaporization line 21, compared to when only vaporization line 21 is provided to generate gaseous gas 12 and supply it to utilization equipment.

[0023] <8> summary As described above, the cooling system according to this embodiment provides at least the following advantageous effects. (1) By adding a liquefaction line 22 for liquefying the gaseous first refrigerant 32 extracted from the subcooler 30 so as to be capable of heat exchange with the evaporation line 21, the efficiency of generating the gaseous gas 12 to be supplied to the utilization equipment can be improved. (2) Since the gaseous first refrigerant 32 extracted from the subcooler 30 is not directly supplied to the utilization equipment, this system can be operated regardless of the purity of the gaseous first refrigerant 32, even in cases where high purity (99.999% or higher, more preferably 99.9999%) is required for the gas to be supplied to the utilization equipment. [Explanation of symbols]

[0024] 10: Tank 11: Gas in liquid state 12: Gaseous gas 20: Heat exchanger 21: Vaporization line 22: Liquefaction line 30: Subcooler 31: Liquid first refrigerant 32: First refrigerant in gaseous state 40: Pump 50:Warmer 60: Compressor A: Superconducting cable B1: One end connection B2: The other end connection C1: Second refrigerant before cooling C2: Second refrigerant after cooling

Claims

1. A cooling system for a superconducting cable used in combination with a gas utilization facility, a tank in which the gas is stored in a liquid state; a heat exchanger having at least a vaporization line and a liquefaction line that are capable of exchanging heat with each other; a subcooler containing a first refrigerant in a liquid state and cooling a second refrigerant circulated within the superconducting cable with the first refrigerant in the liquid state; a pump that draws the first refrigerant in a gaseous state that has evaporated in the subcooler; a heater interposed between the subcooler and the pump for heating the first refrigerant in a gaseous state; a compressor that compresses the first refrigerant in a gaseous state that has been heated by the heater; and The vaporization line is The liquid gas sent from the tank is vaporized and supplied to the equipment. The liquefaction line comprises: The first refrigerant in a gaseous state compressed by the compressor is liquefied and supplied to the subcooler. Cooling system for superconducting cables.

2. The first refrigerant and the gas have the same main element, The purity of the major elements in the first refrigerant in a gaseous state sent to the liquefaction line is lower than the purity of the major elements in the gas in a gaseous state supplied to the facility.

2. The cooling system for a superconducting cable according to claim 1.

3. The gas in gaseous state supplied to the equipment is nitrogen having a purity of 99.999% or more.

3. The cooling system for a superconducting cable according to claim 2.

4. The gas, the first refrigerant, and the second refrigerant are nitrogen.

4. The cooling system for a superconducting cable according to claim 3.

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