JP2016169880A - Superconductive cable cooling device and superconductive cable cooling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconductive cable cooling device which effectively utilizes an evaporative refrigerant occurring during pre-cooling process of a superconductive cable to improve performance of a refrigeration machine and cool a refrigerant gas to a sub-cool temperature in a short time, and to provide a superconductive cable cooling method.SOLUTION: A superconductive cable cooling device includes: an evaporative refrigerant supply line 51 which is branched from an exhaust line 43 and configured to flow an evaporative refrigerant; a temperature sensor 44 which is provided in the exhaust line 43 and detects a temperature of the evaporative refrigerant led out from a superconductive cable 27; and a control device 59 which discharges the evaporative refrigerant from the exhaust line 43 to the atmosphere when the temperature detected by the temperature sensor 44 is higher than a predetermined temperature and supplies the evaporative refrigerant to an evaporative refrigerant supply line 51 when the detected temperature is lower than the predetermined temperature.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a superconducting cable cooling apparatus and a superconducting cable cooling method using the superconducting cable cooling apparatus.

Conventionally, when cooling superconducting power devices such as a superconducting power transmission cable, a superconducting transformer, a superconducting motor, a superconducting current limiter, and a superconducting power storage, liquid nitrogen is used as a refrigerant.
When cooling a superconducting power device, the temperature of the liquefied refrigerant rises when a superconductor (for example, a coil or a cable) constituting the superconducting power device is cooled below its critical temperature.
For this reason, the cooling device for cooling the superconducting power device is configured to include a refrigerator for cooling the liquefied refrigerant, a circulation pump for circulating the refrigerant, and a tank for storing the refrigerant (for example, , See Patent Document 1).

FIG. 3 is a system diagram showing a schematic configuration of a conventional superconducting cable cooling apparatus.
Here, a conventional superconducting cable cooling apparatus 100 will be described with reference to FIG.
A conventional superconducting cable cooling apparatus 100 includes a tank 111, a liquefied refrigerant supply line 113, a pump 116, a refrigerant gas circulation line 117-1, a liquefied refrigerant heat exchanger 117-2, an expansion turbine 117-3, and a refrigerant. A refrigerator 117 including a gas heat exchanger 117-5, a branch line 118, first and second superconducting cable terminals 122 and 124, a liquefied refrigerant recovery line 126, an exhaust line 131, and an open valve 132; Have.

A liquefied refrigerant 112 is stored in the tank 111. The liquefied refrigerant 112 is pumped through the liquefied refrigerant supply line 113 and introduced into the superconducting cable 123 from the first superconducting cable terminal 122.
The refrigerator 117 houses a part of the liquefied refrigerant supply line 113 located on the downstream side of the pump 116 and a part of the refrigerant gas circulation line 117-1. The liquefied refrigerant heat exchanger 117-2 exchanges heat between the liquefied refrigerant flowing through a part of the liquefied refrigerant supply line 113 and the refrigerant gas flowing through a part of the refrigerant gas circulation line 117-1, thereby liquefied refrigerant. Allow to cool.

The liquefied refrigerant recovery line 126 is a line for recovering the liquefied refrigerant led out from the second superconducting cable terminal 124, returning it to the tank 111, and reusing the liquefied refrigerant.
The exhaust line 131 is connected to the second superconducting cable terminal 124. The vaporized refrigerant obtained by vaporizing the liquefied refrigerant is led to the exhaust line 131 via the second superconducting cable terminal 124.

  After the superconducting cable cooling apparatus 100 having the above-described configuration is installed at a target location, a precooling process (a process that does not use the pump 116 and the refrigerator 117) is performed to slowly cool the superconducting cable 123 at room temperature. At this time, since the temperature of the superconducting cable 123 at the start of the precooling process is normal temperature, the liquefied refrigerant is vaporized by the temperature of the superconducting cable 123, and vaporized refrigerant is generated. The vaporized refrigerant is released into the atmosphere through the open valve 132 and the exhaust line 131 without being reused.

In general, since the length of the superconducting cable 123 is very long, such as several kilometers, in order to precool the superconducting cable 123 from room temperature to the saturation temperature of the refrigerant, a large amount of liquefied refrigerant is required.
Further, from the viewpoint of alleviating stress due to thermal contraction of the superconducting cable 123, the precooling process of the superconducting cable 123 is generally performed slowly over several days.

JP 2011-106755 A

By the way, when liquid nitrogen is used as the liquefied refrigerant, the temperature of the vaporized refrigerant (vaporized liquid nitrogen) led out to the exhaust line 131 and released into the atmosphere is lower than the temperature of the atmosphere, and when the pre-cooling process is completed. The temperature is close to 77 K, which is the saturation temperature of liquid nitrogen.
For this reason, the conventional superconducting cable cooling apparatus 100 that discharges the vaporized refrigerant that is led to the exhaust line 131 and can be used as cooling energy to the atmosphere has a problem that the cooling energy cannot be effectively used.
Further, the conventional superconducting cable cooling device 100 has a problem that it takes a very long time from the start to the completion of precooling of the superconducting cable 123.

  Accordingly, the present invention has been made in view of the above circumstances, and by effectively utilizing the vaporized refrigerant generated during the pre-cooling process of the superconducting cable, the performance of the refrigerator is improved, and the liquefied refrigerant can be subcooled in a short time. It is an object of the present invention to provide a superconducting cable cooling device capable of cooling to a temperature and a method of cooling a superconducting cable.

  In order to solve the above-described problem, according to the first aspect of the present invention, a tank in which liquefied refrigerant is stored and one end of which is connected to the lower end of the tank, and the liquefied refrigerant is supplied to the superconducting via one end of a superconducting cable. A liquefied refrigerant supply line that supplies the cable; a pump that is provided in the liquefied refrigerant supply line and that pumps and circulates the liquefied refrigerant through the liquefied refrigerant supply line; a refrigerant gas circulation line that circulates refrigerant gas; and the refrigerant gas circulation line A compressor for compressing the refrigerant gas, an expansion turbine for adiabatic expansion of the refrigerant gas provided in the refrigerant gas circulation line located at a subsequent stage of the compressor, and the refrigerant adiabatically expanded by the expansion turbine Heat for liquefied refrigerant that cools the liquefied refrigerant to a subcooling temperature by exchanging heat between the gas and the liquefied refrigerant flowing through the liquefied refrigerant supply line A refrigerator including a heat exchanger for refrigerant gas that exchanges heat between the refrigerant gas that has passed through the heat exchanger for liquefied refrigerant and the refrigerant gas compressed by the compressor, the tank, and the pump Branched from the liquefied refrigerant supply line located between the refrigeration unit and the superconducting cable, and connected to the liquefied refrigerant supply line located between the refrigerator and the superconducting cable, and a flow rate adjustment provided in the branch line A valve, an exhaust line that is led out from the superconducting cable and discharges the vaporized refrigerant out of the liquefied refrigerant to the atmosphere, a vaporized refrigerant supply line that is branched from the exhaust line and through which the vaporized refrigerant flows, and the exhaust line A temperature sensor that is provided and detects the temperature of the vaporized refrigerant derived from the superconducting cable, and a temperature detected by the temperature sensor is higher than a predetermined temperature. And a controller for discharging the vaporized refrigerant from the exhaust line to the atmosphere and supplying the vaporized refrigerant to the vaporized refrigerant supply line when the temperature is lower than the predetermined temperature. A cooling device is provided.

  According to the invention of claim 2, the vaporized refrigerant supply line arranged in the refrigerant gas heat exchanger is an extension of the refrigerant gas circulation line arranged in the refrigerant gas heat exchanger. Extending in the same direction as the current direction, the vaporized refrigerant supply line is branched in a front stage of the refrigerant gas heat exchanger, and the refrigerant gas circulation line disposed in the refrigerant gas heat exchanger; The control device includes a plurality of branch portions connected at different positions, and the control device supplies the vaporized refrigerant via any one of the plurality of branch portions based on the temperature detected by the temperature sensor. A superconducting cable cooling device according to claim 1 is provided.

  The invention according to claim 3 is characterized in that a valve is provided for each of the vaporized refrigerant supply line and the plurality of branch portions located in the preceding stage of the refrigerant gas heat exchanger. A superconducting cable cooling device according to claim 2 is provided.

  Moreover, according to the invention which concerns on Claim 4, it branches from the said liquefied refrigerant | coolant supply line located between the said pump and the said liquefied refrigerant heat exchanger, and the said liquefied refrigerant heat exchanger and the said superconducting cable A first bypass line that is connected to the liquefied refrigerant supply line positioned therebetween and bypasses the heat exchanger for liquefied refrigerant, and a valve provided in the first bypass line. A superconducting cable cooling device according to any one of claims 1 to 3 is provided.

  Moreover, according to the invention which concerns on Claim 5, the said liquefied refrigerant | coolant which passed the said superconducting cable is derived | led-out by one end, the liquefied refrigerant recovery line by which the other end was arrange | positioned at the upper part in the said tank, the said refrigerator, A connection position between the liquefied refrigerant supply line and the branch line located between the superconducting cable and a branch from the liquefied refrigerant supply line located between the superconducting cables and connected to the liquefied refrigerant recovery line, The superconducting cable cooling according to any one of claims 1 to 4, further comprising: a second bypass line that bypasses the superconducting cable; and a valve provided in the second bypass line. An apparatus is provided.

  According to the invention of claim 6, there is provided a method of cooling a superconducting cable including a precooling process of the superconducting cable, wherein the precooling process of the superconducting cable is performed by supplying the liquefied refrigerant in the tank without passing through a refrigerator. A cable pre-cooling step for supplying the superconducting cable to cool the superconducting cable, and in the cable pre-cooling step, the temperature of the vaporized refrigerant generated by the vaporization of the liquefied refrigerant contributing to cooling of the superconducting cable is predetermined. A vaporized refrigerant supply step of supplying the vaporized refrigerant to a vaporized refrigerant supply line disposed in a refrigerant gas heat exchanger constituting the refrigerator when the temperature is lower than the temperature; and in the refrigerator, the refrigerant Using the gas heat exchanger, heat is exchanged between the refrigerant gas compressed by the compressor and the refrigerant gas that has passed through the liquefied refrigerant heat exchanger and has been lowered in temperature. The refrigerant gas cooling step for cooling the compressed refrigerant gas, the step of adiabatically expanding the precooled refrigerant gas by an expansion turbine, and the adiabatic expansion using the liquefied refrigerant heat exchanger. And a liquefied refrigerant cooling step of cooling the liquefied refrigerant to a subcooling temperature by exchanging heat between the refrigerant gas and the liquefied refrigerant supplied from the tank. The

  According to the invention of claim 7, in the vaporized refrigerant supply step, the position of the heat exchanger for the refrigerant gas into which the vaporized refrigerant is introduced is determined based on the temperature of the vaporized refrigerant. A method of cooling a superconducting cable according to claim 6 is provided.

  Moreover, according to the invention which concerns on Claim 8, this cooling process of the said superconducting cable performed after the pre-cooling process of the said superconducting cable is carried out, and this cooling process of the said superconducting cable passed the said refrigerator with the pump. A main cooling step of supplying liquefied refrigerant to the superconducting cable and main cooling the superconducting cable; and in the main cooling step, a liquefied refrigerant recovering step of recovering the liquefied refrigerant passing through the superconducting cable in the tank; The method of cooling a superconducting cable according to claim 6 or 7, characterized by comprising:

  According to the present invention, by effectively utilizing the vaporized refrigerant generated during the precooling process of the superconducting cable, the performance of the refrigerator can be improved and the liquefied refrigerant can be cooled to the subcooling temperature in a short time.

It is a systematic diagram which shows schematic structure of the superconducting cable cooling device which concerns on the 1st Embodiment of this invention. It is a systematic diagram which shows schematic structure of the superconducting cable cooling device which concerns on the 2nd Embodiment of this invention. It is a systematic diagram which shows schematic structure of the conventional superconducting cable cooling device.

  Embodiments to which the present invention is applied will be described below in detail with reference to the drawings. The drawings used in the following description are for explaining the configuration of the embodiment of the present invention, and the size, thickness, dimensions, etc. of the respective parts shown in the drawings are the dimensional relationships of the actual superconducting cable cooling device. May be different.

(First embodiment)
FIG. 1 is a system diagram showing a schematic configuration of a superconducting cable cooling apparatus according to a first embodiment of the present invention.
Referring to FIG. 1, a superconducting cable cooling apparatus 10 according to a first embodiment includes a tank 11, a liquefied refrigerant supply line 13, valves 15, 33, 53 to 57, a pump 17, and a branch line 21. The flow control valve 22, the first superconducting cable terminal 25, the second superconducting cable terminal 28, the liquefied refrigerant recovery line 31, the pressure adjusting line 35, the pressure gauges 37 and 46, the release valve 38, 47, a refrigerator 41 that cools the liquefied refrigerant 12 that cools the superconducting cable 27 to a subcool temperature, an exhaust line 43, a temperature sensor 44, a vaporized refrigerant supply line 51, a check valve 58, and a control device 59 Have.

  Here, the “subcool temperature” refers to a temperature zone where the liquid is in a subcool state (a state where the liquid is lower than its saturation temperature (temperature at which boiling occurs)). When liquid nitrogen under atmospheric pressure is used as the liquefied refrigerant 12, the subcool temperature refers to a temperature range from the boiling point (about 77K) to the freezing point (about 63K). The saturation temperature refers to a temperature at which the pressure of a certain liquid becomes equal to the saturation vapor pressure.

The tank 11 is a reservoir tank for storing the liquefied refrigerant 12. The structure of the tank 11 is preferably a heat insulating structure using, for example, a vacuum double structure or a heat insulating material from the viewpoint of making it difficult to vaporize the liquefied refrigerant due to the influence of the ambient temperature of the outside air.
The liquefied refrigerant 12 is preferably a substance that can be liquefied in a critical temperature region that can maintain the superconducting state of the superconducting cable 27, and is preferably a highly insulating material in a subcooled state. For example, liquefied nitrogen (liquid nitrogen) can be used as the liquefied refrigerant 12 in consideration of safety and cost.

The liquefied refrigerant supply line 13 has one end connected to the lower end of the tank 11 and the other end connected to the first superconducting cable terminal 25. The liquefied refrigerant supply line 13 supplies the liquefied refrigerant 12 to one end of the superconducting cable 27 via one end of the superconducting cable 27.
The liquefied refrigerant supply line 13 has a section 13A (a part of the liquefied refrigerant supply line 13 positioned between the pump 17 and the first superconducting cable terminal 25) disposed in the liquefied refrigerant heat exchanger 63.

  The valve 15 is provided in the liquefied refrigerant supply line 13 located between the branch position of the branch line 21 and the tank 11. When the valve 15 is opened, the liquid medium 12 in the tank 11 is supplied to the liquefied refrigerant supply line 13 and the branch line 21.

The pump 17 is provided in the liquefied refrigerant supply line 13 located between the branch position of the branch line 21 and the refrigerator 41. The pump 17 pressure-circulates the liquefied refrigerant 12 through the liquefied refrigerant supply line 13.
The pump 17 has a function of pumping the liquefied refrigerant 12 to the superconducting cable 27. When liquefied nitrogen is used as the liquefied refrigerant, as the pump 17, for example, a pump capable of pumping liquefied nitrogen within a range of 30 L / min to 100 L / min may be used.

The branch line 21 is branched from the liquefied refrigerant supply line 13 located between the valve 15 and the pump 17 and connected to the liquefied refrigerant supply line 13 located between the refrigerator 41 and the first superconducting cable terminal 25. ing. The branch line 21 is provided so as to bypass the pump 17 and the refrigerator 41.
The flow rate adjustment valve 22 is provided in the branch line 21. The flow rate adjustment valve 22 is a valve for adjusting the flow rate of the liquefied refrigerant 12 supplied to the downstream side of the flow rate adjustment valve 22.

The first superconducting cable terminal 25 is provided at one end of the superconducting cable 27. The liquefied refrigerant 12 is supplied to one end of the superconducting cable 27 via the first superconducting cable terminal 25.
The second superconducting cable terminal 28 is provided at the other end of the superconducting cable 27. Immediately after the start of the precooling process of the superconducting cable 27 at room temperature, the liquefied refrigerant 12 is easily vaporized due to the temperature of the superconducting cable 27, so that a lot of vaporized refrigerant is generated, and when the precooling process of the superconducting cable 27 comes to an end, Since the superconducting cable 27 is sufficiently cooled, almost no vaporized refrigerant is generated and the liquid refrigerant 12 is led out from the superconducting cable 27.
From the viewpoint of reducing the thermal load caused by intrusion heat from the external environment, the first and second superconducting cable terminals 25 and 28 and the superconducting cable 27 may be, for example, those having a vacuum heat insulating structure.

One end of the liquefied refrigerant recovery line 31 is connected to the second superconducting cable terminal 28. The liquefied refrigerant 12 that has passed through the superconducting cable 27 is led out to one end of the liquefied refrigerant recovery line 31.
The other end of the liquefied refrigerant recovery line 31 is disposed so as to penetrate the upper end of the tank 11 and extend downward. The other end of the liquefied refrigerant recovery line 31 is disposed in the gas phase formed in the upper part of the tank 11.
The valve 33 is provided in the liquefied refrigerant recovery line 31 located in the vicinity of the tank 11. When the valve 33 is opened, the liquefied refrigerant 12 recovered from the superconducting cable 27 is returned into the tank 11 via the second superconducting cable terminal 28.

One end of the pressure adjustment line 35 is disposed in the gas phase formed in the upper portion of the tank 11, and the other end is disposed outside the tank 11. The pressure adjustment line 35 is a line for releasing the pressure in the tank 11 to the outside of the tank 11.
The pressure gauge 37 is provided outside the tank 11 and measures the pressure in the upper part of the tank 11 via the pressure adjustment line 35.
The release valve 38 is provided in the pressure adjustment line 35 located outside the tank 11. The release valve 38 is electrically connected to the pressure gauge 37 and opens and closes according to the pressure of the pressure gauge 37 so that the pressure in the tank 11 becomes a constant pressure.

The refrigerator 41 includes a refrigerant gas circulation line 61, a liquefied refrigerant heat exchanger 63, a compressor 65, a water cooling unit 66, a refrigerant gas heat exchanger 68, and an expansion turbine 69.
The components of the refrigerator 41 except for the compressor 65 and the water cooling unit 66 are accommodated in a vacuum container (cold box) not shown. The vacuum vessel is for suppressing heat intrusion from the outside.

The refrigerant gas circulation line 61 is a loop-shaped line. The refrigerant gas circulation line 61 is a line for circulating the refrigerant gas.
The refrigerant gas circulation line 61 has first to third sections 61A, 61B, 61C. The first section 61 </ b> A is disposed in the liquefied refrigerant heat exchanger 63. Refrigerant gas adiabatically expanded by the expansion turbine 69 is supplied to the first section 61A.
The second and third sections 61B and 61C are disposed in the refrigerant gas heat exchanger 68 and extend in the same direction. The refrigerant gas that has passed through the liquefied refrigerant heat exchanger 63 is supplied to the second section 61B. The refrigerant gas compressed by the compressor 65 is supplied to the third section 61C.

As the refrigerant gas, one having a liquefaction temperature sufficiently lower than the liquefaction temperature of the liquefied refrigerant 12 stored in the tank 11 is used. When liquefied nitrogen is used as the liquefied refrigerant 12, for example, helium gas, neon gas, or a mixed gas obtained by mixing helium gas and neon gas can be used as the refrigerant gas, but neon gas is preferably used.
As described above, the neon gas containing neon having a molecular weight larger than that of helium is used as the refrigerant gas, so that the speed of sound is reduced, and the rotational speed of the compressor 65 and the expansion turbine 69 can be kept low. In addition, the operational reliability of the refrigerator 41 can be improved.

The liquefied refrigerant heat exchanger 63 is provided at a position capable of accommodating the section 13A and the first section 61A. The liquefied refrigerant heat exchanger 63 exchanges heat between the liquefied refrigerant 12 flowing through the section 13A and the refrigerant gas flowing through the first section 61A and cooled by adiabatic expansion by the expansion turbine 69, thereby liquefied refrigerant. Allow 12 to cool to subcool temperature.
The liquefied refrigerant 12 having the subcooling temperature is introduced into the superconducting cable 27 via the first superconducting cable terminal 25. On the other hand, the refrigerant gas that has contributed to the cooling of the liquefied refrigerant 12 moves to the second section 61B and is supplied to the compressor 65 through the second section 61B.
As the liquefied refrigerant heat exchanger 63, for example, an aluminum plate fin heat exchanger can be used from the viewpoint of miniaturization and high performance.

The compressor 65 is provided in the refrigerant gas circulation line 61 located between the second section 61B and the third section 61C.
In the compressor 65, the refrigerant gas is compressed to generate a refrigerant gas having a high temperature and a high pressure. The high-temperature and high-pressure refrigerant gas generated by the compressor 65 is supplied to the water cooling unit 66.

  In FIG. 1, a case where only one compressor 65 is provided is shown as an example, but a plurality of refrigerant gas circulation lines 61 located between the second section 61B and the third section 61C are provided in the refrigerant gas circulation line 61. The compressor 65 may be provided. Thus, by providing a plurality of compressors 65, higher-pressure refrigerant gas can be generated.

  The water cooling unit 66 is provided in the refrigerant gas circulation line 61 located between the compressor 65 and the third section 61C. The water cooling unit 66 cools the temperature of the refrigerant gas at a high temperature and high pressure to near the atmospheric temperature. The refrigerant gas cooled by the water cooling unit 66 is supplied to the third section 61C. For example, a water-cooled cooler can be used as the water-cooling unit 66.

  The refrigerant gas heat exchanger 68 includes first to fourth heat exchange blocks 71 to 74. The 1st thru | or 4th heat exchange block 71-74 is the 1st heat exchange block 71, the 2nd heat exchange block 72, the 3rd with respect to the direction which goes to the heat exchanger 63 for liquefied refrigerants from the water cooling part 66. The heat exchange block 73 and the fourth heat exchange block 74 are arranged in this order. The 1st thru | or 4th heat exchange block 71-74 is arrange | positioned so that a predetermined space | interval may be formed between the other heat exchange blocks provided in the adjacent position.

  The first to fourth heat exchange blocks 71 to 74 perform heat exchange in different temperature ranges. Specifically, the temperature range in which the first heat exchange block 71 can exchange heat is, for example, 230K or more and less than 300K, and the temperature range in which the second heat exchange block 72 can exchange heat is, for example, 180K or more and less than 230K. The temperature range in which the third heat exchange block 73 can exchange heat is, for example, 120K or more and less than 180K, and the temperature range in which the fourth heat exchange block 74 can exchange heat is, for example, 77K or more and less than 120K. it can.

The refrigerant gas heat exchanger 68 flows through the second section 61B, passes through the liquefied refrigerant heat exchanger 63, and flows through the third section 61C and passes through the compressor 65 and the water cooling section 66. Heat exchange with gas.
As the refrigerant gas heat exchanger 68, for example, an aluminum plate fin heat exchanger can be used from the viewpoint of miniaturization and high performance.

The expansion turbine 69 is provided in the refrigerant gas circulation line 61 located between the liquefied refrigerant heat exchanger 63 and the refrigerant gas heat exchanger 68. The expansion turbine 69 cools the refrigerant gas to the subcooling temperature by adiabatically expanding the refrigerant gas.
The expansion turbine 69 and the compressor 65 may be arranged coaxially and integrated. As a result, the power generated in the expansion turbine 69 can be used to drive the compressor 65, so that the refrigerator 41 can be reduced in size and power can be saved.

One end of the exhaust line 43 is connected to the second superconducting cable terminal 28. During the precooling process of the superconducting cable 27, the vaporized refrigerant in which the liquefied refrigerant 12 that has contributed to the cooling of the superconducting cable 27 is vaporized is led to the exhaust line 43 via the superconducting cable terminal 28.
When the temperature of the vaporized refrigerant detected by the temperature sensor 44 is higher than a predetermined temperature (for example, 270 K), the vaporized refrigerant is released into the atmosphere via the exhaust line 43.

The temperature sensor 44 is provided in the exhaust line 43. The temperature sensor 44 is electrically connected to the control device 59. The temperature sensor 44 detects the temperature of the vaporized refrigerant derived from the superconducting cable 27. The temperature sensor 44 transmits the detected temperature of the vaporized refrigerant to the control device 59.
The pressure gauge 46 is provided in the exhaust line 43 and measures the pressure in the exhaust line 43. The release valve 47 is provided in the exhaust line 43.

The vaporized refrigerant supply line 51 is branched from an exhaust line 43 located at the subsequent stage of the temperature sensor 44, and is a line through which the vaporized refrigerant flows.
The vaporized refrigerant supply line 51 is a line through which the vaporized refrigerant flows, and includes a section 76 and branch portions 77 to 79. The section 76 is accommodated in the refrigerant gas heat exchanger 68. The section 76 extends in the same direction as the extending direction of the second and third sections 61B and 61C, and a part thereof is accommodated in the first to fourth heat exchange blocks 71 to 74.

  The branch portion 77 is a line branched from the vaporized refrigerant supply line 51 located in the preceding stage of the refrigerant gas heat exchanger 68 and is located between the third heat exchange block 73 and the fourth heat exchange block 74. Connected to the section 76. The branch part 77 is a line for supplying the vaporized refrigerant only to the first to third heat exchange blocks 71 to 73.

The branching part 78 is a line branched from the branching part 77 and is connected to a section 76 located between the second heat exchange block 72 and the third heat exchange block 73. The branch part 78 is a line for supplying vaporized refrigerant only to the first and second heat exchange blocks 71 and 72.
The branch portion 79 is a line branched from the branch portion 78 and is connected to a section 76 located between the first heat exchange block 71 and the second heat exchange block 72. The branch portion 79 is a line for supplying the vaporized refrigerant only to the first heat exchange block 71.

The valve 53 is provided in the vaporized refrigerant supply line 51 located in the preceding stage of the refrigerant gas heat exchanger 68. The valve 54 is provided at a branching portion 77 located in the preceding stage of the refrigerant gas heat exchanger 68. The valve 55 is provided at a branching portion 78 located in the front stage of the refrigerant gas heat exchanger 68.
The valve 56 is provided at a branching portion 79 located in the front stage of the refrigerant gas heat exchanger 68. The valve 57 is provided in the vaporized refrigerant supply line 51 located at the rear stage of the refrigerant gas heat exchanger 68. The check valve 58 is provided in the vaporized refrigerant supply line 51 located at the rear stage of the valve 57. The check valve 58 is a valve for preventing back diffusion of the atmosphere.

The control device 59 includes a storage unit (not shown) and a control unit (not shown). The storage unit (not shown) has a predetermined temperature of the vaporized refrigerant (for example, 270 K), a first temperature range (for example, 230 K or more and less than 300 K), a second temperature range (for example, 180 K or more and less than 230 K), A third temperature range (for example, 120K or more and less than 180K), a fourth temperature range (for example, 77K or more and less than 120K), a program related to the overall control of the superconducting cable cooling device 10, and the like are stored.
The control unit (not shown) controls the superconducting cable cooling device 10 based on a program stored in a storage unit (not shown). The control unit (not shown) is electrically connected to the temperature sensor 44 and the valves 53 to 57.

At the time of precooling the superconducting cable 27, the control device 59 performs the following control.
When the temperature of the vaporized refrigerant detected by the temperature sensor 44 is lower than the predetermined temperature and within the first temperature range, the valve 53 is opened and the valves 55 to 56 are closed, so that the branch portions 77 to 79 are opened. Control to supply the vaporized refrigerant to the section 76 is performed without using it.
Further, when the temperature of the vaporized refrigerant detected by the temperature sensor 44 is lower than the predetermined temperature and within the second temperature range, the valves 53, 55, and 56 are closed and the valve 54 is opened, so that the branch portion A control for supplying the vaporized refrigerant to the section 76 is performed via 77.
Further, when the temperature of the vaporized refrigerant detected by the temperature sensor 44 is lower than the predetermined temperature and within the third temperature range, the valves 53, 54, and 56 are closed and the valve 55 is opened, so that the branch portion Control to supply vaporized refrigerant to the section 76 is performed via 78.
Further, when the temperature of the vaporized refrigerant detected by the temperature sensor 44 is lower than the predetermined temperature and is within the fourth temperature range, the valves 53 to 55 are closed and the valve 56 is opened, so that the branch portion 79 is opened. Then, control for supplying the vaporized refrigerant to the section 76 is performed.

  Thus, the vaporized refrigerant is supplied so that the performance of the first to fourth heat exchange blocks 71 to 74 can be improved by changing the position to be supplied to the section 76 according to the temperature of the vaporized refrigerant. Thus, by effectively utilizing the cold energy of the vaporized refrigerant, the cold heat of the vaporized refrigerant can be used efficiently.

According to the superconducting cable cooling device of the first embodiment, by including the vaporized refrigerant supply line 51, the temperature sensor 44, and the control device 59 described above, conventionally, the superconducting cable is released into the atmosphere during the precooling process. The vaporized refrigerant having the cold heat supplied to the refrigerant gas heat exchanger 68 can be effectively used.
Thereby, since the performance of the refrigerator 41 that cools the liquefied refrigerant 12 is improved, the liquefied refrigerant 12 can be cooled to the subcooling temperature in a short time.

  In the first embodiment, the case where the refrigerant gas heat exchanger 68 is configured by four heat exchange blocks (first to fourth heat exchange blocks 71 to 74) is described as an example. What is necessary is just to determine the number of heat exchange blocks according to the temperature distribution of the heat exchanger 68 for refrigerant gas, and it is not limited to four. Moreover, it is applicable also to the heat exchanger for refrigerant | coolant gas comprised only with one heat exchange block.

  In the first embodiment, the case where the control device 59 is provided has been described as an example. For example, instead of providing the control device 59, the user can visually check the temperature detected by the temperature sensor 44. A display screen may be provided, and the user may manually open and close the valves 53 to 57 based on the temperature displayed on the display screen. In this case, the same effect as that of the first embodiment can be obtained.

  Further, as time elapses from the start of the operation of the refrigerator 41, the temperature of the refrigerant gas that passes through the refrigerant gas heat exchanger 68 and is introduced into the compressor 65 is lowered, and the pressure is also gradually lowered. In order to reduce the pressure, a refrigerant gas replenishment line (not shown) is provided, and the refrigerant gas is replenished from the refrigerant gas replenishment line to the refrigerant gas circulation line 61, whereby the pressure on the inlet side of the compressor 65 is increased. It can be held constant. Thereby, the discharge pressure can be kept constant in the compressor 65.

Next, a superconducting cable cooling method according to the first embodiment using the superconducting cable cooling apparatus 10 shown in FIG. 1 will be described with reference to FIG.
First, the precooling process of the superconducting cable 27 will be described.
Immediately after the installation of the superconducting cable cooling apparatus 10 is completed, the temperature other than the vicinity of the tank 11 in which the liquefied refrigerant (for example, liquid nitrogen) is stored is room temperature. For this reason, a precooling process for the superconducting cable 27 is required as a stage before the superconducting cable 27 is finally cooled.

First, the superconducting cable 27 is cooled by supplying a predetermined flow rate of the liquefied refrigerant 12 in the tank 11 to the superconducting cable 27 via the branch line 21 bypassing the pump 17 and the flow control valve 22 (cable precooling step). .
When the superconducting cable 27 at room temperature is brought into contact with the liquefied refrigerant 12, the object to be cooled may be destroyed due to stress (thermal shock) due to thermal contraction. In the cable precooling step, the liquefied refrigerant 12 is supplied without going through the refrigerator 41.

The liquefied refrigerant 12 in contact with the normal temperature superconducting cable 27 is vaporized as the temperature rises. The vaporized refrigerant that is the vaporized liquefied refrigerant 12 is opened to the atmosphere via the section 76, the valve 57, and the check valve 58 by opening the valve 53. At this time, when a large amount of vaporized refrigerant is generated, it is released into the atmosphere via the release valve 47.
In the initial stage of the cable pre-cooling process, a vaporized refrigerant having a high temperature is generated. As time elapses, the temperature of the vaporized refrigerant gradually decreases, and the temperature of the vaporized refrigerant eventually approaches the temperature of the liquefied refrigerant 12.
Note that the temperature of the vaporized refrigerant is continuously detected using the temperature sensor 44, and the detected temperature is transmitted to the control device 59.

After pre-cooling of the superconducting cable 27 is started, the refrigerator 41 is started and the refrigerator 41 is pre-cooled. By the way, in starting of the refrigerator 41, after starting the pre-cooling of the superconducting cable 27, it may be started after being left for a relatively long time or may be started in a short time.
Here, the case where the refrigerator 41 is started in a relatively short time after the pre-cooling of the superconducting cable 27 is started, that is, a case where a large amount of vaporized refrigerant is released by the pre-cooling of the superconducting cable 27 will be described as an example. Will be explained.

  In the cable pre-cooling step, when the temperature of the vaporized refrigerant generated by vaporizing the liquefied refrigerant that has contributed to the cooling of the superconducting cable 27 becomes lower than a predetermined temperature (for example, 270 K), the refrigerant constituting the refrigerator 41 The vaporized refrigerant is supplied to the vaporized refrigerant supply line 51 disposed in the gas heat exchanger 68 (vaporized refrigerant supply step).

Next, the refrigerator 41 is started. When the refrigerator 41 is started, the compressor 65 constituting the refrigerator 41 adiabatically compresses the refrigerant gas. The pressure of the refrigerant gas on the high pressure side is, for example, about 1 to 2 MPa. The compressed refrigerant gas having a high temperature is cooled to room temperature by the water cooling unit 66 and passes through the refrigerant gas heat exchanger 68.
In the refrigerant gas heat exchanger 68, the refrigerant gas compressed by the compressor 65 and the refrigerant gas passing through the liquefied refrigerant heat exchanger 63 and subjected to heat exchange are compressed. Refrigerant gas is cooled (refrigerant gas cooling step).

  In the expansion turbine 69, the temperature of the refrigerant gas is lowered by adiabatically expanding the precooled refrigerant gas. The outlet temperature of the expansion turbine 69 depends on the turbine inlet temperature, and the turbine inlet temperature decreases with time due to heat exchange. Therefore, the turbine outlet temperature falls by about 10 to 15 K due to adiabatic expansion with respect to the turbine inlet temperature. At this time, the pressure of the refrigerant gas after adiabatic expansion is, for example, about 0.5 to 1 MPa.

  The liquefied refrigerant heat exchanger 68 cools the liquefied refrigerant 12 to the subcooling temperature by exchanging heat between the adiabatically expanded refrigerant gas and the liquefied refrigerant 12 supplied from the tank 11 (liquefied refrigerant cooling step).

In the case of the conventional superconducting cable cooling apparatus 100 shown in FIG. 3, the refrigerant gas cooled by the expansion turbine 117-3 passes through the liquefied refrigerant heat exchanger 117-2, and passes through the refrigerant gas heat exchanger 117-5. By becoming a cooling gas, the refrigerant gas before being introduced into the expansion turbine 117-3 is further cooled, and repeated circulation advances, so that the transfer of thermal energy is stabilized and adiabatic expansion is performed in the expansion turbine 117-3. The temperature of the refrigerant gas becomes the subcool temperature.
For this reason, at the initial stage of precooling of the superconducting cable 123, the temperature of the refrigerant gas introduced into the expansion turbine 117-3 has not been sufficiently cooled by the refrigerant gas heat exchanger 117-5, so adiabatic expansion is performed. Therefore, it cannot be cooled to the subcooling temperature.

However, in the present embodiment, since the temperature of the refrigerant gas heat exchanger 68 is lowered by the vaporized refrigerant supplied from the vaporized refrigerant supply line 51, the refrigerant gas can be cooled more efficiently than before. It becomes possible.
For this reason, since the temperature of the refrigerant gas at the inlet side of the expansion turbine 69 becomes lower than before when the refrigerator 41 is started, the liquefied refrigerant can be cooled to the subcool temperature in a short time.

By the way, after the operation of the refrigerator 41, a temperature gradient is generated in the refrigerant gas heat exchanger 68 due to the circulation of the refrigerant gas. For this reason, when passing the vaporized refrigerant | coolant from which temperature differs through the refrigerant | coolant gas heat exchanger 68, it becomes necessary to pass the heat exchange block of a suitable temperature range.
The control device 59 determines the position of the refrigerant gas heat exchanger 68 for introducing the vaporized refrigerant based on the temperature of the vaporized refrigerant detected by the temperature sensor 44, and sets the position before the branch portions 77 to 79 and the branch portion 77. The vaporized refrigerant is supplied to a portion of the refrigerant gas heat exchanger 68 in an appropriate temperature range via any one of the vaporized refrigerant supply lines 51 positioned.
Thereby, since it becomes possible to improve the characteristic of the refrigerator 41 efficiently, the liquefied refrigerant | coolant 12 can be cooled to subcool temperature in a short time.

Next, the main cooling process of the superconducting cable 27 performed after the precooling process of the superconducting cable 27 will be described.
In the main cooling process of the superconducting cable 27, the liquefied refrigerant 12 that has passed through the refrigerator 41 is supplied to the superconducting cable 27 by the pump 17, and the superconducting cable 27 is actually cooled. And a liquefied refrigerant recovery step of recovering the liquefied refrigerant 12 that has passed through 27 into the tank 11 via the liquefied refrigerant recovery line 31.

As described above, in the precooling process of the superconducting cable 27, first, the superconducting cable 27 is precooled to a liquefaction temperature corresponding to the pressure of the liquefied refrigerant, and then the amount of the liquefied refrigerant 12 to be vaporized is decreased. 22 is closed, the pump 17 is started, and the liquefied refrigerant 12 is circulated to complete the process.
When the pre-cooling process is completed, the vaporization of the liquefied refrigerant almost disappears, but the vaporized refrigerant slightly vaporized is led to the vaporized refrigerant supply line 51 provided with the valve 53 to effectively use the cold energy, It becomes possible to drive.

According to the cooling method of the superconducting cable of the first embodiment, by having a cable precooling step, a vaporized refrigerant supply step, a refrigerant gas cooling step, a step of adiabatically expanding the refrigerant gas, and a liquefied refrigerant cooling step, During the pre-cooling process of the superconducting cable 27, the vaporized refrigerant having the cold heat that has been released to the atmosphere can be supplied to the refrigerant gas heat exchanger 68 to effectively use the vaporized refrigerant.
Thereby, since the performance of the refrigerator 41 that cools the liquefied refrigerant 12 is improved, the liquefied refrigerant 12 can be cooled to the subcooling temperature in a short time.

(Second Embodiment)
FIG. 2 is a system diagram showing a schematic configuration of a superconducting cable cooling apparatus according to the second embodiment of the present invention. In FIG. 2, the same components as those of the superconducting cable cooling apparatus 10 of the first embodiment shown in FIG.

  Referring to FIG. 2, the superconducting cable cooling device 85 of the second embodiment further includes a first bypass line 86 and valves 87 and 89 in addition to the configuration of the superconducting cable cooling device 10 of the first embodiment. The configuration is the same as that of the superconducting cable cooling device 10 except that the second bypass line 88 is provided.

The first bypass line 86 is branched from the liquefied refrigerant supply line 13 located between the pump 17 and the liquefied refrigerant heat exchanger 63, and is connected to the liquefied refrigerant heat exchanger 63 and the first superconducting cable terminal 25. It is connected to a liquefied refrigerant supply line 13 located between them. The first bypass line 86 bypasses the liquefied refrigerant heat exchanger 63.
The first bypass line 86 may be arranged in a cold box (not shown). The valve 87 is provided in the first bypass line 86.

By the way, when the refrigerator 41 is operated constantly in the rated operation state and the heat load of the superconducting cable 27 increases in the time zone when the amount of power transmitted through the superconducting cable 27 increases, the subcooling temperature is increased in the liquefied refrigerant heat exchanger 63. The cooling capacity is insufficient with only the cooled refrigerant.
However, by having the first bypass line 86 and the valve 87, when the heat load is small, a part of the liquefied refrigerant stored in the tank 11 is passed through the first bypass line 86 and the valve 87. A large amount can be directly supplied to the superconducting cable 27.
At this time, by controlling the rotation speed of the pump 17 using an inverter, the flow rate of the liquefied refrigerant is increased, so that the increase in the thermal load can be endured even when the refrigerator 41 is in the rated operation state.

The second bypass line 88 is branched from the liquefied refrigerant supply line 13 located between the connection position of the branch line 21 and the first superconducting cable terminal 25, and is connected to the liquefied refrigerant recovery line 31. The second bypass line 88 bypasses the superconducting cable 27. The second bypass line 88 is preferably arranged on the refrigerator 41 side, not on the first superconducting cable terminal 25 side.
The valve 89 is provided in the second bypass line 88.

When the amount of power transmitted through the superconducting cable 27 is reduced by having the second bypass line 88 and the valve 89, the liquefied refrigerant when the thermal load of the superconducting cable 27 is reduced during the rated operation of the refrigerator 41. A portion of the liquefied refrigerant 12 that is cooled to the subcooling temperature by the heat exchanger 63 and has a small heat load passes through the second bypass line 88 and the valve 89, the superconducting cable 27, and the first and second By bypassing the second superconducting cable terminals 25 and 28 and returning to the tank 11, the temperature of the liquefied refrigerant in the tank 11 can be lowered.
In other words, the liquefied refrigerant in the tank 11 can be stored cold using the cold energy generated in the cooling device 41.

  According to the superconducting cable cooling device of the second embodiment, when the superconducting cable 27 is cooled, the circulation amount of the liquefied refrigerant that cools the superconducting cable 27 is changed in accordance with the increase or decrease of the thermal load, so By collecting the cold energy into the tank 11 or supplying it from the tank 11, the rated operation of the refrigerator 41 can be maintained, so that the failure frequency and maintenance frequency of the refrigerator 41 can be reduced. Therefore, stable operation can be realized.

Note that the superconducting cable cooling device 85 of the second embodiment can obtain the same effects as the superconducting cable cooling device 10 of the first embodiment.
Also in the second embodiment, instead of providing the control device 59, the valves 53 to 56 may be manually opened and closed.

Next, with reference to FIG. 2, a method for cooling the superconducting cable of the second embodiment will be briefly described.
In the first embodiment described above, when the temperature of the liquefied refrigerant 12 near the outlet of the second superconducting cable terminal 28 reaches the liquefying temperature, the precooling of the superconducting cable 27 is completed.
At this time, the liquefied refrigerant 12 is not evaporated, but if held as it is, the liquefied refrigerant is warmed and evaporated by various heat loads.
For this reason, it is necessary to operate the refrigerator 41 and the pump 17 to circulate the liquefied refrigerant 12 and to always cool the liquefied refrigerant 12 to a subcool temperature rather than the liquefying temperature by the liquefied refrigerant heat exchanger 63 of the refrigerator 41.

  The circulation of the liquefied refrigerant 12 is increased from the tank 11 through the valve 15 by the pump 17 and sent to the liquefied refrigerant heat exchanger 63 of the refrigerator 41. The liquefied refrigerant 12 is cooled in the liquefied refrigerant heat exchanger 63 to its subcooling temperature (about 65 K when the liquefied refrigerant 12 is liquid nitrogen).

  Then, the liquefied refrigerant 12 cooled to the subcooling temperature by the liquefied refrigerant heat exchanger 63 is introduced into the superconducting cable 27 via the first superconducting cable terminal 25, and the superconducting cable 27 is cooled to the subcooling temperature in the superconducting state. Then, it is returned from the second superconducting cable terminal 28 into the tank 11 via the valve 33.

According to the cooling method of the superconducting cable of the second embodiment, when the superconducting cable 27 is cooled, the circulation amount of the liquefied refrigerant that cools the superconducting cable 27 is changed according to the increase or decrease of the thermal load, so It is possible to maintain the rated operation of the refrigerator 41 by collecting or supplying the cold energy in the tank 11.
Thereby, since it becomes possible to reduce the failure frequency and maintenance frequency of the refrigerator 41, stable operation | movement is realizable.
In addition, the cooling method of the superconducting cable of the second embodiment can obtain the same effect as the cooling method of the superconducting cable of the first embodiment.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and within the scope of the present invention described in the claims, Various modifications and changes are possible.

In the first and second embodiments, the case of cooling the superconducting cable 27, which is one of the superconducting power devices, has been described as an example. However, the superconducting cable cooling devices 10 and 85 are other The present invention can also be applied to cooling superconducting transformers, superconducting motors, superconducting fault current limiters, superconducting power storages, etc., which are superconducting power devices.
The superconducting cable cooling method described in the first and second embodiments can also be used when cooling a superconducting transformer, a superconducting motor, a superconducting current limiter, a superconducting power storage, and the like.

  The present invention is applicable to a superconducting cable cooling device and a superconducting cable cooling method.

  DESCRIPTION OF SYMBOLS 10,85 ... Superconducting cable cooling device, 11 ... Tank, 13 ... Liquid refrigerant supply line, 13A, 76 ... Section, 15, 33, 53-57, 87, 89 ... Valve, 17 ... Pump, 21 ... Branch line, 22 ... Flow control valve, 25 ... first superconducting cable terminal, 27 ... superconducting cable, 28 ... second superconducting cable terminal, 31 ... liquefied refrigerant recovery line, 35 ... pressure adjusting line, 37,46 ... pressure gauge, 38 , 47 ... Open valve, 41 ... Refrigerator, 43 ... Exhaust line, 44 ... Temperature sensor, 51 ... Vaporized refrigerant supply line, 58 ... Check valve, 59 ... Control device, 61 ... Refrigerant gas circulation line, 61A ... First , 61B ... second section, 61C ... third section, 63 ... heat exchanger for liquefied refrigerant, 65 ... compressor, 66 ... water cooling section, 68 ... heat exchanger for refrigerant gas, 69 ... expansion turbine 71 ... 1st heat exchange block, 72 ... 2nd heat exchange block, 73 ... 3rd heat exchange block, 74 ... 4th heat exchange block, 77-79 ... Branching part, 86 ... 1st bypass Line, 88 ... second bypass line

Claims (8)

A tank in which liquefied refrigerant is stored;
One end is connected to the lower end of the tank, and via one end of the superconducting cable, the liquefied refrigerant supply line that supplies the liquefied refrigerant to the superconducting cable;
A pump provided in the liquefied refrigerant supply line, for pumping and circulating the liquefied refrigerant to the liquefied refrigerant supply line;
A refrigerant gas circulation line that circulates the refrigerant gas, a compressor that is provided in the refrigerant gas circulation line, compresses the refrigerant gas, and is provided in the refrigerant gas circulation line that is positioned downstream of the compressor, and insulates the refrigerant gas An expansion turbine for expansion, and a heat exchanger for liquefied refrigerant that cools the liquefied refrigerant to a subcooling temperature by exchanging heat between the refrigerant gas adiabatically expanded by the expansion turbine and the liquefied refrigerant flowing through the liquefied refrigerant supply line A refrigerator including a refrigerant gas heat exchanger that exchanges heat between the refrigerant gas that has passed through the liquefied refrigerant heat exchanger and the refrigerant gas compressed by the compressor;
A branch line branched from the liquefied refrigerant supply line located between the tank and the pump, and connected to the liquefied refrigerant supply line located between the refrigerator and the superconducting cable;
A flow control valve provided in the branch line;
An exhaust line that is derived from the superconducting cable and discharges the vaporized vaporized refrigerant out of the liquefied refrigerant, and
A vaporized refrigerant supply line branched from the exhaust line and through which the vaporized refrigerant flows;
A temperature sensor that is provided in the exhaust line and detects the temperature of the vaporized refrigerant derived from the superconducting cable;
When the temperature detected by the temperature sensor is higher than a predetermined temperature, the vaporized refrigerant is discharged from the exhaust line to the atmosphere, and when the temperature is lower than the predetermined temperature, the vaporized refrigerant is supplied to the vaporized refrigerant supply line. A control device to supply;
A superconducting cable cooling device characterized by comprising: The vaporized refrigerant supply line arranged in the refrigerant gas heat exchanger extends in the same direction as the refrigerant gas circulation line arranged in the refrigerant gas heat exchanger,
The vaporized refrigerant supply line has a plurality of branch portions that are branched in a stage preceding the refrigerant gas heat exchanger and connected at different positions from the refrigerant gas circulation line disposed in the refrigerant gas heat exchanger. And
2. The superconducting cable according to claim 1, wherein the control device supplies the vaporized refrigerant through any one of the plurality of branch portions based on a temperature detected by the temperature sensor. Cooling system.   The superconducting cable cooling device according to claim 2, wherein a valve is provided for each of the vaporized refrigerant supply line and the plurality of branch portions located in a preceding stage of the refrigerant gas heat exchanger. Branched from the liquefied refrigerant supply line located between the pump and the liquefied refrigerant heat exchanger and connected to the liquefied refrigerant supply line located between the liquefied refrigerant heat exchanger and the superconducting cable. A first bypass line that bypasses the liquefied refrigerant heat exchanger;
A valve provided in the first bypass line;
The superconducting cable cooling device according to any one of claims 1 to 3, wherein the superconducting cable cooling device is provided. The liquefied refrigerant that has passed through the superconducting cable at one end is led out, and the other end is disposed in the upper part of the tank, and a liquefied refrigerant recovery line is disposed.
Branching from the liquefied refrigerant supply line located between the connection position of the liquefied refrigerant supply line and the branch line located between the refrigerator and the superconducting cable, and the superconducting cable, and collecting the liquefied refrigerant A second bypass line connected to the line and bypassing the superconducting cable;
A valve provided in the second bypass line;
The superconducting cable cooling device according to any one of claims 1 to 4, wherein the superconducting cable cooling device is provided. A method of cooling a superconducting cable including a precooling process of the superconducting cable,
The precooling process of the superconducting cable is a cable precooling step of cooling the superconducting cable by supplying the liquefied refrigerant in the tank to the superconducting cable without passing through a refrigerator.
In the cable pre-cooling step, when the temperature of the vaporized refrigerant generated by vaporizing the liquefied refrigerant that has contributed to the cooling of the superconducting cable becomes lower than a predetermined temperature, heat for the refrigerant gas constituting the refrigerator A vaporized refrigerant supply step of supplying the vaporized refrigerant to a vaporized refrigerant supply line disposed in the exchanger;
In the refrigerator, by using the refrigerant gas heat exchanger, heat exchange is performed between the refrigerant gas compressed by the compressor and the refrigerant gas that has passed through the liquefied refrigerant heat exchanger and is at a low temperature. A refrigerant gas cooling step for cooling the compressed refrigerant gas;
Adiabatic expansion of the precooled refrigerant gas by an expansion turbine;
Using the liquefied refrigerant heat exchanger, the liquefied refrigerant cooling step of cooling the liquefied refrigerant to a subcooling temperature by exchanging heat between the refrigerant gas expanded adiabatically and the liquefied refrigerant supplied from the tank;
A method for cooling a superconducting cable, comprising:   The method for cooling a superconducting cable according to claim 6, wherein, in the vaporized refrigerant supply step, the position of the refrigerant gas heat exchanger into which the vaporized refrigerant is introduced is determined based on the temperature of the vaporized refrigerant. Including the main cooling process of the superconducting cable performed after the precooling process of the superconducting cable,
The main cooling process of the superconducting cable is a main cooling step of supplying the liquefied refrigerant that has passed through the refrigerator by the pump to the superconducting cable, and cooling the superconducting cable.
In the main cooling step, a liquefied refrigerant recovery step of recovering the liquefied refrigerant that has passed through the superconducting cable in the tank;
The method of cooling a superconducting cable according to claim 6 or 7, characterized by comprising:

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