KR102337181B1 - Cooling system for superconducting machine - Google Patents

Abstract

The present invention relates to a cooling system for a superconducting device. The cooling system for a superconducting device according to the present invention includes a superconducting storage tank in which a superconductor is accommodated, and a low-temperature liquid and gas are accommodated therein, and the interior of the superconducting storage tank A circulation line for circulating the low-temperature liquid accommodated in the circulating line, a cooling tank for cooling the low-temperature liquid moving through the circulation line, and the pressure of the gas accommodated in the superconducting storage tank using the low-temperature liquid moved through the circulation line It is characterized in that it comprises a pressure tank for pressurizing the.
According to the present invention as described above, it relates to a low-temperature cooling system suitable for cooling large superconducting devices such as superconducting current limiters and similar superconducting magnets, transformers, and energy storage devices such as flywheels, and more specifically, a cooling device and a pressurization system There is an advantage in that temperature uniformity and stability can be secured by circulating and cooling a low-temperature liquid supercooled by a superconducting power device.

Description

Cooling system for superconducting devices {COOLING SYSTEM FOR SUPERCONDUCTING MACHINE}

The present invention relates to a low-temperature cooling system suitable for cooling large superconducting devices such as superconducting current limiters and similar superconducting magnets, transformers, and energy storage devices such as flywheels, and more specifically, to a low-temperature liquid supercooled by a cooling device and a pressurization system. It relates to a cooling system for a superconducting device that can ensure temperature uniformity and stability by circulating and cooling the superconducting power device.

Power technology has been considered to have reached the limit of technological development in its long history and on a large scale. However, superconducting power devices are attracting attention as a new technology to solve the continuously increasing demand for power, its density, and the demand for eco-friendliness.

Superconductors have completely zero electrical resistance below the critical state specified by temperature, magnetic field and current density, and are suitable for realizing high-efficiency power devices due to their high current density.

For electric power devices that are responsible for the socio-economic foundation, it is most important to secure operational reliability and ease of operation. In the case of superconducting power devices, the biggest obstacle to commercialization is low-temperature cooling technology.

Superconductors require a low-temperature environment below -196°C. Therefore, a large-capacity low-temperature cooling system is required for superconducting power devices, but low-temperature technology is still insufficiently developed worldwide. Therefore, it can be called a technical huddle that lowers the reliability of the entire system and increases the difficulty of operation.

Conventionally, superconducting devices were mainly cooled by immersion in a low-temperature liquid, and the temperature was maintained with a refrigerator. Here, the low-temperature liquid may be liquid nitrogen. This is to ensure stability by absorbing thermal shock from the liquid when the current load changes rapidly.

In such a cooling system, due to the special environment of high voltage of power equipment, it is necessary to suppress the generation of bubbles in the liquid and to increase the overall insulation performance.

Therefore, it is desirable to create a sub-cooled state by lowering the temperature and increasing the pressure. However, since heat from the surroundings continues to heat the liquid, and on the other hand, the refrigerator continues to reliquefy the gas, there is a tendency to change to a saturated state in which liquefaction and evaporation occur actively as a whole.

The prior art related to superconducting device cooling is Korean Patent Laid-Open Patent No. 10-2007-0036027 (Title of the Invention: Cooling System for Superconducting Power Device, Publication Date: April 02, 2007).

The problems of the superconducting device cooling system according to the prior art as described above are as follows. 5 is a diagram of a cooling system for a superconducting power device according to the prior art is shown.

The cooling system for a superconducting power device according to the prior art, as shown in FIG. 5, is for cooling the superconducting cable 11 of the joist. The low-temperature liquid is stored in the inside (1b) of the reservoir tank (1), forced to circulate using the circulation pump (5), cooled through the refrigerator (7), and the pressure of the low-temperature container is increased through the carburetor Nos. 17 to 18 to supercool the low temperature It is a structure to obtain a circulation loop of liquid.

This has a limitation in that it cannot be applied to large-capacity superconducting power devices such as superconducting current limiters, transformers, and energy storage devices, such as superconducting current limiters, transformers, and energy storage devices, where only the size of the superconductor reaches several meters.

The present invention has been devised to solve the above problems, and an object of the present invention is to provide a low-temperature cooling system suitable for cooling large superconducting devices such as superconducting current limiters and similar superconducting magnets, transformers, and energy storage devices such as flywheels, More particularly, it relates to a cooling system for a superconducting device capable of securing temperature uniformity and stability by circulating and cooling a low-temperature liquid supercooled by a cooling device and a pressurization system to a superconducting power device.

In addition, by locating the low-temperature liquid supply line at the bottom of the superconducting storage tank and placing the recovery line near the liquid level, it is possible to maintain a constant liquid level at all times. Rather, it relates to a cooling system for superconducting devices that can make the internal temperature uniform.

In order to solve the above problems, the cooling system for a superconducting device according to the present invention includes a superconducting storage tank in which a superconductor is accommodated, a low-temperature liquid and gas are accommodated therein, and a low-temperature liquid accommodated in the superconducting storage tank. A circulation line for circulating the , a cooling tank for cooling the low-temperature liquid moved through the circulation line, and the low-temperature liquid moved through the circulation line for pressurizing the pressure of the gas accommodated in the superconducting storage tank It is characterized in that it includes a pressurized tank.

In addition, the circulation line includes a liquid recovery pipe for moving the low-temperature liquid from the superconducting storage tank to the cooling tank, and a liquid supply pipe for supplying the low-temperature liquid cooled in the cooling tank to the superconducting storage tank. characterized in that

In addition, the cooling tank includes a heat exchanger for cooling the low-temperature liquid flowing into the cooling tank from the liquid recovery pipe, and supplying the low-temperature liquid from the liquid recovery pipe to the heat exchanger, and supplying the low-temperature liquid cooled in the heat exchanger. A circulation pump for moving the liquid supply pipe to the superconducting storage tank as a medium, and a second low-temperature liquid at least partially in contact with the outside of the heat exchanger to exchange heat with the heat exchanger are included.

In addition, the cooling tank, characterized in that it further includes a cooling device for maintaining the temperature of the second low-temperature liquid.

In addition, one side of the liquid recovery pipe is installed at a predetermined height of the superconducting storage tank, and one side of the liquid supply pipe is installed at the lowermost part of the superconducting storage tank.

In addition, the low-temperature liquid cooled in the heat exchanger has a temperature below the low-temperature liquid accommodated in the superconducting storage tank.

In addition, the gas in the superconducting storage tank is characterized in that it has a pressure higher than the saturation pressure of the low-temperature liquid.

In addition, in the pressurized tank, a low-temperature liquid and a gas are accommodated therein, and the low-temperature liquid moving through the liquid recovery pipe may be branched and introduced, and the space in which the gas is accommodated is the gas inside the superconducting storage tank. It is characterized in that it is connected to the space in which it is accommodated and a gas supply pipe to maintain the same pressure.

In addition, the pressurized tank is characterized in that it further includes a heat source for regulating the pressure of the superconducting storage tank by vaporizing the low-temperature liquid accommodated therein to increase the pressure of the gas.

In addition, it is characterized in that a gas discharge pipe for adjusting the pressure of the gas accommodated in the pressure tank is further included.

In addition, the cooling tank may further include an emergency cooling device that is operated when the cooling device malfunctions.

According to the present invention as described above, it relates to a low-temperature cooling system suitable for cooling large-scale superconducting devices such as superconducting current limiters and similar superconducting magnets, transformers, and energy storage devices such as flywheels, and more specifically, a cooling device and a pressurization system There is an advantage in that temperature uniformity and stability can be secured by circulating and cooling the low-temperature liquid supercooled by the superconducting power device.

In addition, by locating the low-temperature liquid supply line at the bottom of the superconducting storage tank and placing the recovery line near the liquid level, it is possible to maintain a constant liquid level at all times. However, there is an advantage in that the internal temperature can be uniformed.

1 is a conceptual diagram of a cooling system for a superconducting device according to a first embodiment of the present invention.
2 is a conceptual diagram of a cooling system for a superconducting device according to a second embodiment of the present invention.
3 is a conceptual diagram of a cooling system for a superconducting device according to a third embodiment of the present invention.
4 is a conceptual diagram of a cooling system for a superconducting device according to a fourth embodiment of the present invention.
5 is a diagram of a cooling system for a superconducting power device according to the prior art is shown.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Like reference numerals in each figure indicate like elements. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted so as not to obscure the gist of the present invention.

<First embodiment>

1 is a conceptual diagram of a cooling system for a superconducting device according to a first embodiment of the present invention.

The first embodiment of the present invention includes a superconducting storage tank 100 for storing the superconductor 110 therein. The superconducting storage tank 100 may be a double low-temperature container (cryostat) including an insulating layer on the outside.

In the superconducting storage tank 100, there may be a subcooled low-temperature liquid 101 for at least partially maintaining the superconductor 110 at a low temperature. The supercooled low-temperature liquid 101 as described above may be, for example, a low-temperature liquid (N _{2 ).}

The supercooled low-temperature liquid 101 can always maintain a supercooled state, which is a temperature below the boiling point, by the operation of the entire system.

In particular, when the superconductor 110 is a superconducting current-limiting module for current limitation, the internal pressure may suddenly increase because the low-temperature liquid evaporates quickly during operation.

Therefore, in order to buffer this, a layer of gaseous nitrogen gas may exist inside the superconducting storage tank 100 , and this gas 102 is the same material (nitrogen) as the subcooled low-temperature liquid 101 . gas) may be

A liquid level 103 exists as a boundary between the gas 102 and the liquid at a specific location. This may be above 70% of the height of the superconducting storage tank 100 .

Current introducing lines 111 and 112 electrically connected from the outside to pass current to the superconductor 110 may be included in the superconducting storage tank 100 .

The superconducting storage tank 100 in the super-cooled low-temperature liquid 101 is cooled to maintain a low temperature, the first embodiment includes a cooling tank 200, this cooling tank 200 having a double insulation layer It may be a low-temperature container of

In addition, a circulation line, which is a pipe for circulating the subcooled low-temperature liquid 101 accommodated in the superconducting storage tank 110 to the cooling tank 200 and the pressure tank 300 to be described later is provided, which will be described later. It includes a liquid recovery pipe 120 and a liquid supply pipe 130 to be used.

The inside of the cooling tank 200 may include at least partially saturated low-temperature liquid 201, which is usually a low-temperature liquid. In order to always maintain the saturated low-temperature liquid 201 at the target temperature T1 , the cooling tank 200 includes a cooling device 240 .

A heat exchanger 210 may be installed inside the cooling tank 200 , and the heat exchanger 210 may be a pipe type heat exchanger. The heat exchanger 210 is for cooling the low-temperature liquid flowing into the cooling tank 200 from the liquid recovery pipe 120 .

The saturated low-temperature liquid 201 is a second low-temperature liquid, and is in contact with the outside of the heat exchanger 210 at least partially to exchange heat with the heat exchanger 210 .

The superconducting low-temperature liquid 101 accommodated in the superconducting storage tank 100 is transferred to the heat exchanger 210 through the liquid recovery pipe 120 connected from the upper part of the superconducting storage tank 100 to the heat exchanger 210 by the circulation pump 220 . ), and the circulation pump 220 may be located inside the cooling tank 200, but is not limited thereto.

The temperature of the subcooled low-temperature liquid 101 flowing into the heat exchanger 210 may be lowered very close to T1 through heat exchange with the saturated low-temperature liquid 201 .

The saturated low-temperature liquid 201 may evaporate to become a gas 202, which is re-liquefied by the cooling device 240 so that the temperature and pressure inside the cooling tank 200 may be maintained close to a normal state. have.

In this case, the pressure P1 may be a saturation pressure corresponding to the temperature T1.

The supercooled low-temperature liquid 101 cooled through the heat exchanger 210 may remove foreign substances in the liquid while passing through the filter 230 , and may pass through the filter 230 before passing through the heat exchanger 210 . .

The subcooled low-temperature liquid 101 cooled as described above may be supplied back to the superconducting storage tank 100 through the liquid supply pipe 130 connected to the lowermost portion of the superconducting storage tank 100 .

As described above, the relatively cold subcooled low-temperature liquid 101 is introduced from the lower portion of the superconducting storage tank 100 and is diffused or laminated inside the storage tank 100, and is near the upper liquid level of the superconducting storage tank by natural convection. Since the collected relatively warm supercooled low temperature liquid 101 is again recovered toward the cooling tank 200 by the liquid recovery pipe 120, the overall temperature of the superconducting low temperature liquid 101 inside the superconducting storage tank 100 is equal to T1 or It can be maintained at a slightly higher temperature T1', and the maximum temperature difference inside can be maintained within 1°C.

The position of the liquid recovery pipe 120 may be located at a predetermined height in consideration of at least the depth of thermal diffusion from the liquid level 103 and the volume change according to the temperature change of the supercooled low-temperature liquid 101, and the liquid level decreases due to an abnormality Thus, when the liquid recovery pipe 120 goes down below the position, the circulation pump 220 stops and the entire system stops, so that an abnormal phenomenon can be quickly detected and dealt with.

Since the inside of the superconducting storage tank 100 may be a high voltage, a pressure of P2 higher than the saturation pressure of T1 can be maintained in order to obtain a high dielectric strength and maximally suppress the occurrence of gas bubbles inside the supercooled low-temperature liquid 101. .

Accordingly, in order to increase the internal pressure of the superconducting storage tank 100 , the first embodiment includes a pressurized tank 300 connected to the inside of the superconducting storage tank 100 and having the same pressure P2 .

The pressurized tank 300 may be a double low-temperature vessel with a heat insulating layer, at least partially capable of storing a saturated low-temperature liquid 301 therein, and the saturated low-temperature liquid 301 is a saturation temperature T2 corresponding to the pressure P2. can

The saturated low-temperature liquid 301 and the subcooled low-temperature liquid 101 are the liquid replenishment pipe 330 under the pressurized tank 300 and the liquid recovery pipe 120 at the top of the superconducting storage tank 100 or the liquid supply pipe at the bottom It may be fluidly connected by a mechanical connection between the 130 , and may be the same material (liquid nitrogen).

The saturated low-temperature liquid 301 accommodated in the pressurized tank 300 may be heated by a heat source 310 such as a heater to maintain a saturated state, and this heat source is contained inside or outside the pressurized tank 300 to be saturated. Heat exchange with the low-temperature liquid 301 may be performed.

The pressurized tank 300 may have, at least partially, a gas 302 layer having the same composition as that of the saturated low-temperature liquid 301 , and this space is the gas 102 layer and the gas of the superconducting storage tank 100 . It may be connected by a supply pipe 340 .

The gas supply pipe 340 may be opened and closed by a manual or electric valve, and when the superconducting storage tank 100 needs to be pressurized, the heat output control device of the heat source not shown in the schematic diagram determines the pressure of each tank By controlling the heat output of the heat source by evaporating the saturated low-temperature liquid 301 contained in the pressurized tank 300, the pressure of the gas 302 layer can be increased, and the gas supply pipe 340 is open, so that the superconducting storage tank It is possible to increase the pressure of the gas 102 layer together.

Conversely, when the pressure is too high, the on/off valve that the gas discharge pipe 320 may include is opened by the valve control device omitted in the schematic diagram to release the gas to the outside, thereby lowering the pressure to a predetermined pressure or less.

Finally, the pressure inside the superconducting storage tank 100 may be maintained by this operation.

When the liquid level 303 of the saturated liquid 301 in the pressurized tank 300 is lowered below a certain level, the liquid replenishment pipe 330 at the bottom of the pressurized tank 300 is opened by the valve control device omitted from the schematic diagram. The subcooled low-temperature liquid 101 branched from the recovery pipe 120 may be replenished.

The liquid supplement pipe 330 is connected to the liquid recovery pipe 120 that recovers the supercooled low temperature liquid 101 from the superconducting storage tank 100 to the heat exchanger 210, so that a part of the supercooled low temperature liquid 101 is pressurized. As it flows into the tank 300, it is replenished with a saturated liquid to restore the liquid level 303 above a certain level.

<Second embodiment>

2 is a conceptual diagram of a cooling system for a superconducting device according to a second embodiment of the present invention.

In the second embodiment of the present invention, almost all parts and operation principles are the same as those of the first embodiment, but the stability is supplemented. When the basic cooling device 240 is stopped for reasons such as power failure, the system temperature rises and the superconducting device may lose its function.

In preparation for such an emergency situation, an emergency cooling device 251 capable of cooling the saturated low-temperature liquid 201 inside the cooling tank 200, and the device and the cooling tank 200 are connected, normally closed, in case of an emergency. The second embodiment differs from the first embodiment in that it includes an emergency valve 250 that is opened to the .

The emergency cooling device 251 can operate for a short time within a few hours (time for maintaining the cooling device 240), and an exhaust pump (not shown) for cooling the saturated low-temperature liquid 201 in a reduced pressure manner. ), a vaporizer (not shown), and the like.

<Third embodiment>

3 is a conceptual diagram of a cooling system for a superconducting device according to a third embodiment of the present invention.

The third embodiment of the present invention has a structure in which the supercooled low-temperature liquid 101 circulates from the recovery pipe 120 through the supply pipe 130 while simultaneously exchanging heat with the cooling device 241 directly. Unlike the second embodiment, the cooling tank 200 and the saturated low-temperature liquid 201 accommodated in the inside of the cooling tank 200 can be omitted, so that the overall structure can be simplified.

In this case, the cooling device 241 used may be different from the cooling device 240 of the first and second embodiments in a heat exchange method, and the cooling device 240 of the first and second embodiments described above. ) may be of a type for re-liquefying a gas into a liquid, and the cooling device 241 of the third embodiment may be a type of device for lowering the temperature of the liquid. A plurality of cooling devices 241 of the third embodiment may be connected in parallel between the liquid recovery pipe 120 and the liquid supply pipe 130 .

Since the operation principle of the remaining parts is the same as that of the first and second embodiments described above, a detailed description thereof will be omitted.

<Fourth embodiment>

4 is a conceptual diagram of a cooling system for a superconducting device according to a fourth embodiment of the present invention.

The fourth embodiment of the present invention may have a simpler structure than the above-described third embodiment, and the overall size of the system may also be reduced.

The superconducting low-temperature liquid 101 inside the superconducting storage tank 100 may be partially separated by a low-temperature liquid pressurization pipe 350, and may be vaporized in the pipe through a heater or heat source 310 that heats the pipe.

Since the low-temperature liquid pressurization pipe 350 is connected to the evaporative gas 102 space of the super-cooled low-temperature liquid 101 inside the superconducting storage tank 100, the vaporization in the pipe will soon increase the pressure inside the superconducting storage tank 100. can cause

When the pressure rises, the gas can be discharged to the outside by opening and closing the valve of the gas nitrogen discharge pipe 360, or block the inflow of the supercooled low-temperature liquid 101 into the low-temperature liquid pressurization pipe 350, or a heat source ( 310) to control the pressure.

Other operating principles are the same as those of the first and third embodiments described above.

Best embodiments have been disclosed in the drawings and specification. Here, although specific terms have been used, these are only used for the purpose of describing the present invention and are not used to limit the meaning or scope of the present invention described in the claims. Therefore, it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

100-superconducting storage tank 101-low temperature liquid
110-Liquid Return Piping
120 - liquid supply piping
200 - cooling tank 201 - low temperature liquid
210 - heat exchanger
300 - pressurized tank 301 - low temperature liquid

Claims (11)

A superconducting storage tank in which a superconductor is accommodated, and a low-temperature liquid and gas are accommodated therein;
a circulation line for circulating the low-temperature liquid accommodated in the superconducting storage tank;
a cooling tank for cooling the low-temperature liquid moving through the circulation line;
and a pressure tank for pressurizing the pressure of the gas accommodated in the superconducting storage tank using the low-temperature liquid moved through the circulation line,
The circulation line is
a liquid recovery pipe for moving the low-temperature liquid from the superconducting storage tank to the cooling tank;
A liquid supply pipe for supplying the low-temperature liquid cooled in the cooling tank to the superconducting storage tank is included.
The gas inside the superconducting storage tank has a pressure higher than the saturation pressure of the low-temperature liquid,
In the pressurized tank, low-temperature liquid and gas are accommodated therein, and the low-temperature liquid moving through the liquid recovery pipe may be branched and introduced, and the space in which the gas is accommodated is the space in which the gas inside the superconducting storage tank is accommodated and Superconducting device, characterized in that it is connected via a gas supply pipe to maintain the same pressure, and vaporizes the low-temperature liquid contained therein to increase the pressure of the gas, and a heat source for adjusting the pressure of the superconducting storage tank is further included. of cooling system. delete The method according to claim 1,
In the cooling tank,
a heat exchanger for cooling the low-temperature liquid flowing into the cooling tank from the liquid recovery pipe;
a circulation pump for supplying a low-temperature liquid from the liquid recovery pipe to the heat exchanger and moving the low-temperature liquid cooled in the heat exchanger to the superconducting storage tank through the liquid supply pipe;
and a second low-temperature liquid at least partially in contact with the outside of the heat exchanger to exchange heat with the heat exchanger. 4. The method according to claim 3,
In the cooling tank,
A cooling system for a superconducting device, characterized in that it further includes a cooling device for maintaining the temperature of the second low-temperature liquid. The method according to claim 1,
One side of the liquid recovery pipe is installed at a preset height of the superconducting storage tank,
One side of the liquid supply pipe is a cooling system for a superconducting device, characterized in that it is installed at the bottom of the superconducting storage tank. 4. The method according to claim 3,
The cooling system of a superconducting device, characterized in that the low-temperature liquid cooled in the heat exchanger has a temperature equal to or lower than the low-temperature liquid accommodated in the superconducting storage tank. delete delete delete The method according to claim 1,
The cooling system of the superconducting device, characterized in that it further comprises a gas discharge pipe for adjusting the pressure of the gas accommodated in the pressurized tank. 5. The method according to claim 4,
In the cooling tank,
The cooling system of a superconducting device, characterized in that it further includes an emergency cooling device that is operated when the cooling device malfunctions.

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