MX2008001256A - Refrigeration system for superconducting devices - Google Patents

Abstract

A system for cooling one or more discrete superconducting devices (21,22, 23) wherein a primary refrigerator (1) subcools cryogenic liquid for desubcooling in the devices (21, 22, 23) and subsequently resubcools this liquid in a recirculation loop (27, 28, 29), and additional cryogenic liquid is maintained in a subcooled condition within a reserve storage container (2) by diversion of some of the refrigeration generated by the primary refrigerator (1) into the reserve storage container (2).

Description

REFRIGERATION SYSTEM FOR SUPERCONDUCTION DEVICES Field of the Invention This invention relates generally to the provision of cooling or cooling to one or more superconducting devices. BACKGROUND OF THE INVENTION Superconductivity is the phenomenon where certain metals, alloys and compounds, such as YBCO, REBCO and BSCCO, at very low temperatures lose electrical resistance so that they have infinite electrical conductivity. It is important in the use of superconducting devices that the cooling, i.e. cooling, provided for the superconducting device does not fall below a certain level so that the wire does not lose its ability to superconduct and the function of the device is compromised. Often cooling is provided by a cryogenic liquid and consumed in the device by heating the liquid. Most devices will not tolerate a liquid gas phase of the refrigerant due to electrical considerations. Brief Description of the Invention One aspect of the invention is: A method for providing refrigeration to a superconducting device comprising: (A) using the refrigeration generated by a main cooler to cool the cryogenic liquid, and passing the cryogenic liquid cooled to at least one superconducting device to provide cooling to the superconducting device; (B) using the refrigeration generated by the main refrigerator to subcool the cryogenic liquid, passing the subcooled cryogenic liquid to a storage reserve container, and keeping the liquid within the storage reserve container in a sub-condition chilled and (C) passing subcooled liquid from the storage stock container to the superconducting device to provide cooling to the superconducting device. Another aspect of the invention is: An apparatus for providing cooling to a superconducting device: (A) a main cooler, at least one superconducting device, and means for passing the cryogenic liquid from the main cooler to the superconducting device; (B) a stock storage container, and means for passing the cryogenic liquid from the main refrigerator to the stock storage container; and (C) means for passing the cryogenic liquid from the stock storage container to the superconducting device. As used herein the term "temperature "cryogenic" means a temperature at or below 120 K. As used herein, the term "cryocooler" means a refrigeration machine capable of achieving and maintaining cryogenic temperatures.As used herein the term "superconductor" means a material that loses all its resistance to the conduction of an electric current once the material achieves a certain cryogenic temperature. As used herein, the term "refrigeration" means the ability to reject heat from a sub-ambient temperature entity. As used herein, the term "indirect heat exchange" means bringing entities into a heat exchange relationship without any contact or intermingling of the entities with each other. As used herein, the term "subcooling" means cooling a liquid to be at a temperature lower than the saturation temperature of that liquid by the existing pressure. As used herein, the term "direct heat exchange" means the transfer of cooling through the contact of cooling and heating entities.

As used herein, the term "superconducting device" means a device that uses superconducting material, for example, as a superconducting cable. of low temperature or high temperature or in the form of wire for the coils of a rotor for a generator or motor, or for the coils of a magnet or a transformer. Brief Description of the Drawings Figure 1 is a schematic representation of a preferred embodiment of the cooling system of the cryogenic superconductor of the invention. Figure 2 is a schematic representation of one embodiment of the cooling system of the cryogenic superconductor of the invention showing a supply option for the cryogenic liquid. The numbers in the drawings are equal for the common elements. Detailed Description of the Invention The invention will be described in greater detail with reference to the drawings. Referring now to Figure 1, there is shown the main cooler 1 that generates the cooling that cools the cryogenic liquid to pass to one or more superconducting devices. The main cooler 1 is preferably a cryocooler. Any convenient cryocooler can be used in the practice of this invention. Among such cryoinfibers one can name the Stirling cryocoolers, Gifford-McMahon cryocoolers and pulse tube coolers. A pulse tube refrigerator is a refrigeration system closed that oscillates a working gas in a closed cycle and thus make heat load transfers from a cold section to a hot section. The frequency and phase of oscillations are determined by the configuration of the system. The pressure wave driver or generator may be a piston or some other mechanical compression device, or an acoustic or thermoacoustic wave generating device, or any other convenient device for providing a pulse or compression wave to a working gas. That is, the pressure wave generator supplies energy to the working gas inside the pulse tube that causes pressure and velocity oscillations. Helium is the preferred working gas; however, any effective working gas can be used in the pulse tube cooler and among such may be named nitrogen, oxygen, argon and neon or mixtures containing one or more thereof such as air.

The oscillating working gas is preferably cooled in a post-cooler and then in a regenerator as it moves towards the cold end. The geometry and pulse configuration of the pulse tube cooling system is such that the oscillating working gas in the cold head expands for some fraction of the pulsation cycle and the heat is absorbed by the working gas by the heat exchange indirect that provides cooling to the cryogenic liquid. The pulse tube cooling system preferably uses a tube and an acoustic reservoir to maintain the pressure pulses and displacement of gas in appropriate phases. The size of the reservoir is sufficiently large so that the very small pressure oscillation essentially occurs in it during the oscillating flow. The components of the cryocooler include the mechanical compression equipment (pressure wave generator), the tube and sound tank, the final heat rejection system and electrical components required to drive and control the cryocooler. Electric power is mainly converted into acoustic energy in the pressure wave generator. This acoustic energy is transferred by the oscillating working gas to the cold head via a transfer tube. The transfer tube connects the pressure wave generator with the post-cooler located at the hot end of the cold head where the heat is removed as previously described. The cryogenic liquid, which has been subcooled by the refrigeration generated by the main cooler 1, is passed on line 6 to one or more superconducting devices, shown representatively in figure 1 as articles 21, 22 and 23 that have entry lines 24, 25 and 26 respectively. Among the cryogenic liquids that can be used in the practice of this invention one may name liquid nitrogen, liquid helium, liquid argon, and liquid neon, as well as mixtures comprising one or more of these liquids. Examples of superconducting devices that can be used in the practice of this invention include transformers, generators, motors, current fault regulators / limiters, electronic / cellular transmitters, high temperature or low temperature superconducting cables, infrared sensors, magnetic superconducting energy storage systems, and magnets as they should be used in magnetic resonance imaging systems or other industrial applications. When a plurality of superconducting devices receives cooling of the cryogenic liquid, the devices could all be of the same type of device or two or more of the devices could be of different types of devices. On the other hand, the devices could be connected in a functional way or another and could also be part of a facility such as a super-substation or superconducting.

After providing cooling to the superconducting device (s) the de-subcooled cryogenic liquid is now returned to the main cooler in a return spiral where it returns, is re-subcooled and passed back to the superconducting device (s). In the embodiment of the invention illustrated in FIG. 1, the return spiral comprises the output lines 27, 28 and 29, respectively, of the superconducting devices 21, 22 and 23, where each one is fed on line 7 to return to the Main cooler 1. In a certain period, the cryogenic liquid that recirculates between the main cooler and the superconducting device (s) you will need refueling due to vaporization losses. Such replenishment will come from the cryogenic liquid stored in the storage storage container 2. The cryogenic liquid from the storage storage container 2 will also be provided to the superconducting device (s) in case of failure or other shutdown of the main refrigerator. When the cryogenic liquid is provided from the storage reserve container 2 to the superconducting device (s) it is imperative that the cryogenic liquid be in an under-cooled condition to ensure an adequate amount of cooling for the superconducting device (s) and to insure against the formation of any gas inside the devices. In the practice of this invention the cryogenic liquid within the storage reserve container is maintained in a subcooled condition. The cryogenic liquid, which has been subcooled by the cooling generated by the main cooler 1, is passed in the storage storage container 2, such as through line 4 that branches off line 6. Simultaneously, some liquid cryogenic storage container 2 is passed to the main refrigerator 1 to collect more sub-cooling, such as through line 5 that connects to line 7. In this way the contents of storage storage container 2 is maintained in a sub-cooled condition. When necessary, the cryogenic liquid subcooled from the container of storage reserve 2 is passed to the superconducting device (s) to provide cooling to the superconducting device (s), such as through line 8 connecting to line 6. The entry of the subcooled cryogenic liquid from the container storage reserve to the superconducting device (s) may occur during the entry of the subcooled cryogenic liquid from the main cooler to the superconducting device (s), for at least part of the time, and / or may occur after such entry. In fact, the entry of the subcooled cryogenic liquid from the storage storage container to the superconducting device (s) may occur prior to the entry of the cryogenic liquid from the main cooler to the superconducting device (s), such as during the start-up of the system. . Frequently the cryogenic liquid inside the storage reserve container is filled. Figure 2 illustrates an arrangement of the fill wherein the cryogenic fill liquid is provided from the tank car 15. Preferably the cryogenic liquid filling is subcooled before it is passed into the storage stock container. In the embodiment illustrated in figure 2, the cryogenic liquid of the tank car 15 is passed in the full line 16 to the auxiliary cooler 10 where it is subcooled, and from there it is passed on line 11 in the storage reserve container. 2. The auxiliary refrigerator 10 is powered by the auxiliary power source 12. The auxiliary refrigerator 10 it preferably comprises a vacuum pumping system since it reduces appreciably the scale of the auxiliary energy source needed. On the other hand, as illustrated in Figure 2, where the cryogenic liquid is liquid hydrogen, the hydrogen gas vented from the vacuum pump cooler can be passed on line 13 to the fuel cell 14 to drive the cell fuel, whose outlet can lead to the vacuum pump motor. Alternatively, the cryogenic liquid can be passed from the tank car to the storage reserve container without subcooling so that all subcooling is done by the main cooler, or the cryogenic liquid from the tank car can be subcooled by a cooler. mounted auxiliary portable carriage before being passed in storage storage container. Although the invention has been described in detail with reference to certain preferred embodiments, those skilled in the art will recognize that there are other embodiments of the invention within the spirit and scope of the claims.

Claims (20)

1. Method for providing refrigeration to a superconducting device comprising: (A) using the refrigeration generated by a main cooler to cool the cryogenic liquid, and passing the cryogenic liquid cooled in at least one superconducting device to provide cooling to the superconducting device; (B) using the refrigeration generated by the main cooler to subcool cryogenic liquid, passing the subcooled cryogenic liquid to a storage reserve container, and maintaining the liquid within the storage reserve container in a subcooled condition; and (C) passing the subcooled liquid from the stock storage container to the superconducting device to provide cooling to the superconducting device.

2. Method according to claim 1, wherein at least the part of step (C) is carried out simultaneously with step (A).

3. Method according to claim 1, wherein step (C) is carried out after step (A).

4. Method according to claim 1, wherein step (C) is carried out before step (A).

Method according to claim 1, in wherein the cryogenic liquid of the main cooler is passed to a plurality of discrete superconducting devices.

6. Method according to claim 5, wherein the superconducting devices are all of the same type.

7. Method according to claim 5, wherein the superconducting devices are not all of the same type.

8. Method according to claim 5, wherein the superconducting devices comprise a superconducting substation.

9. Method according to claim 1, wherein the cryogenic liquid comprises at least one liquid nitrogen, liquid helium, liquid argon, and liquid neon.

10. Method according to claim 1, further comprising passing the cryogenic liquid from a tank car into the storage reserve container.

11. Method according to claim 10, wherein the cryogenic liquid from the tank car is subcooled before being passed in the storage reserve container.

12. Apparatus for providing refrigeration to a superconducting device comprising: (A) a main cooler, at least one superconducting device, and means for passing the cryogenic liquid from the main cooler to the superconducting device; (B) a stock storage container, and means for passing the cryogenic liquid from the main refrigerator to the stock storage container; and (C) means for passing the cryogenic liquid from the stock storage container to the superconducting device.

Apparatus according to claim 12 wherein the main cooler is a cryocooler.

14. Apparatus according to claim 13, wherein the cryocooler is a pulse tube cooler.

Apparatus according to claim 12, further comprising an auxiliary cooler and means for passing subcooled cryogenic liquid from the auxiliary cooler into the storage stock container.

Apparatus according to claim 15, further comprising a fuel cell and means for passing the fluid from the auxiliary cooler to the fuel cell.

17. Apparatus according to claim 12, comprising a plurality of superconducting devices for receiving cryogenic liquid from the main refrigerator and from the storage reserve container.

18. Apparatus according to claim 17, wherein the superconducting devices are all of the same type.

19. Apparatus according to claim 17, wherein the superconducting devices are not all of the same kind.

20. Apparatus according to claim 17, wherein the superconducting devices comprise a superconducting substation.