CN109920581B - Mixed insulating medium of liquid nitrogen and liquefied carbon tetrafluoride and preparation method thereof - Google Patents
Mixed insulating medium of liquid nitrogen and liquefied carbon tetrafluoride and preparation method thereof Download PDFInfo
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- CN109920581B CN109920581B CN201910176816.2A CN201910176816A CN109920581B CN 109920581 B CN109920581 B CN 109920581B CN 201910176816 A CN201910176816 A CN 201910176816A CN 109920581 B CN109920581 B CN 109920581B
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 249
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 124
- 239000007788 liquid Substances 0.000 title claims abstract description 108
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title description 6
- 239000007789 gas Substances 0.000 claims abstract description 66
- 238000007710 freezing Methods 0.000 claims abstract description 17
- 230000008014 freezing Effects 0.000 claims abstract description 17
- 238000001816 cooling Methods 0.000 claims abstract description 10
- 239000003949 liquefied natural gas Substances 0.000 claims abstract description 8
- 230000001105 regulatory effect Effects 0.000 claims abstract description 6
- 238000003860 storage Methods 0.000 claims description 31
- 238000000034 method Methods 0.000 claims description 16
- 238000005303 weighing Methods 0.000 claims description 6
- 238000009413 insulation Methods 0.000 claims description 4
- 238000009835 boiling Methods 0.000 abstract description 5
- 229910001873 dinitrogen Inorganic materials 0.000 abstract 1
- 239000001307 helium Substances 0.000 description 5
- 229910052734 helium Inorganic materials 0.000 description 5
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 229910052754 neon Inorganic materials 0.000 description 5
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 5
- 239000003507 refrigerant Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000011810 insulating material Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 2
- 238000010292 electrical insulation Methods 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000002595 magnetic resonance imaging Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000374 eutectic mixture Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000009965 odorless effect Effects 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 229910021521 yttrium barium copper oxide Inorganic materials 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
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Abstract
A mixed insulating medium of liquid nitrogen and liquefied carbon tetrafluoride is prepared from nitrogen gas with purity greater than or equal to 99% and carbon tetrafluoride gas with purity greater than or equal to 99%. The proportion of the liquid nitrogen to the liquefied carbon tetrafluoride is (2-90%): (98-10%) in terms of a molar ratio. Under the condition that the molar ratio of liquid nitrogen to liquefied carbon tetrafluoride is 45-90%, the freezing point of the prepared mixed insulating medium can be regulated to 52-60K, and the cooling requirement of electrical equipment in a temperature region below the liquid nitrogen is met; under the condition that the molar ratio of liquid nitrogen to liquefied carbon tetrafluoride is 2-20%, the normal-pressure boiling point of the prepared mixed insulating medium can be regulated to 89K-120K, and the cooling requirement of electrical equipment in a liquefied natural gas temperature region is met. The mixed insulating medium adopts a liquid nitrogen heat exchanger or a refrigerating machine at a liquid nitrogen temperature region to treat high-purity nitrogen and high-purity CF4Carrying out liquefaction; determining high-purity nitrogen and high-purity CF according to the requirements of freezing point and bubble point of mixed insulating medium4The ratio of gas. The mixed insulating medium can be used for electrician equipment in a temperature area below liquid nitrogen and a liquefied natural gas temperature area.
Description
Technical Field
The invention relates to liquid nitrogen and liquefied CF4A hybrid insulating medium and a method of making the same.
Background
Liquid nitrogen is an important cryogenic refrigerant and is also a liquid insulating material, and is mainly used in various electric equipment such as superconducting cables, superconducting transformers, superconducting current limiters, superconducting energy storage devices and the like. The superconducting electrical equipment is cooled by soaking, a low-temperature environment for normal work is provided for the superconducting electrical equipment, the effect of improving the electrical insulation strength is achieved, and the normal operation of the superconducting electrical equipment is directly influenced.
Carbon tetrafluoride (CF)4) At normal temperature, the gas is colorless, odorless, non-combustible and water-insoluble compressible gas and can be used as a low-temperature refrigerant and an insulating gas. The boiling point of the carbon tetrafluoride under normal pressure is about 145K, the melting point is 89.6K, the liquefied carbon tetrafluoride has good electrical insulation performance, and can form an eutectic mixture with liquid nitrogen, as shown in figure 1, the freezing point can reach about 52K, as shown in figure 2, and the bubble point can reach about 145K at the highest.
At normal pressure, the boiling point of liquid nitrogen is about 77K, at which most high temperature superconducting materials can work properly. Currently, electrical equipment such as superconducting cables, superconducting current limiters, superconducting transformers, and superconducting motors are generally cooled directly by liquid nitrogen, while electrical equipment using a strong magnetic field, such as superconducting energy storage (SMES) and magnetic resonance imaging (MRI/NMR) systems, are mainly cooled by direct conduction using liquid helium (4.2K), liquid neon (20K), and a refrigerator. Helium and neon are low in content on the earth, and the liquefaction cost is high, so that the large-scale popularization of the helium and neon is limited. Electrical equipment directly cooled by conduction through a refrigerator has poor thermal stability compared with electrical equipment directly soaked in liquid, and has the insulation problem under low vacuum, so that large-scale popularization is limited. Generally speaking, the critical current of the high-temperature superconducting material at the freezing point of liquid nitrogen of 65K is 2 times that of 77K, if the temperature is continuously reduced, no proper low-temperature liquid insulating material is available at present, and liquid nitrogen and liquefied CF are utilized4Mixed insulating media, coagulation thereofThe fixed point can be continuously reduced to about 52K, the critical current of the high-temperature superconducting material under a 50K self-field is 3-4 times that under 77K, as shown in figure 3, the current carrying capacity and the magnetic field of superconducting electrical equipment can be greatly improved, and in addition, nitrogen and CF (CF)4The cost of the gas is lower, the insulating capability is much higher than that of helium and neon, and the method has important significance for miniaturization and cost reduction of superconducting electrical equipment.
In addition, with the development of superconducting technology, the critical temperature of superconducting materials is continuously increased, and the superconducting materials can work in a liquefied natural gas temperature zone (90K-120K) or even higher temperature zones. In this temperature region, it can be cooled by a mixed working medium throttling refrigerator or an inverse brayton refrigerator with higher efficiency than a liquid nitrogen refrigerator. However, at higher temperatures, there is a lack of corresponding liquid insulating materials for the insulation and cooling of superconducting electrical equipment. The pressure of liquid nitrogen is over 0.3MPa at 90K and over 0.6MPa at 100K, which brings difficulties to the design, manufacture, operation and maintenance of pressure vessels and superconducting electrical equipment. There is an urgent need for a low-temperature insulating cooling medium which can operate in the temperature range of 90-120K. At present, a plurality of Freon refrigerants such as R124, R32, R125, R134a and mixed refrigerants thereof have poor low-temperature insulating performance, carbon precipitation phenomenon exists under a strong electric field, and some low-temperature refrigerants damage an ozone layer and cannot be widely applied to high-voltage electrical equipment.
Therefore, it is necessary to develop a novel low-temperature liquid insulating material which is green and environment-friendly, has a simple preparation process and a working temperature of 50-140K.
Disclosure of Invention
The invention aims to provide a liquid nitrogen and liquefied carbon tetrafluoride mixed insulating medium and a preparation method thereof, aiming at the defects that the existing low-temperature liquid insulating medium is difficult to work in a temperature region below liquid nitrogen such as 50K-60K and the like and a temperature region of liquefied natural gas such as 90K-120K, has poor electrical insulating property, is complex in preparation process and the like.
In order to achieve the purpose, the invention adopts the following technical scheme:
the mixed insulating medium is prepared by nitrogen with the purity of more than or equal to 99 percent and carbon tetrafluoride gas with the purity of more than or equal to 99 percent, and the proportion of the liquid nitrogen to the liquefied carbon tetrafluoride is (2-90 percent): (98-10%) in terms of a molar ratio. Under the condition that the molar ratio of liquid nitrogen to liquefied carbon tetrafluoride is 45-90%, the freezing point of the prepared mixed insulating medium can be regulated to 52-60K, and the cooling requirement of electrician equipment in a temperature region below the liquid nitrogen is met. Under the condition that the molar ratio of liquid nitrogen to liquefied carbon tetrafluoride is 2-20%, the normal-pressure boiling point of the prepared mixed insulating medium can be regulated to 89K-120K, and the cooling requirement of electrical equipment in a liquefied natural gas temperature region is met. The freezing point and the bubble point of the mixed insulating medium are measured by a calorimeter or a phase balance device, and the insulating property is measured by adopting a high-voltage test power supply and a standard liquid voltage-resistant test electrode according to the national standard GB/T507-. The mixed liquid insulating medium can not only reach the insulating strength equivalent to that of liquid nitrogen, but also meet the engineering application requirements of 52K-145K at the liquefaction temperature.
Liquid nitrogen and liquefied CF of the present invention4The mixed insulating medium can be prepared by the following two methods:
the method comprises the following steps:
high-purity nitrogen and CF in nitrogen bottle by using liquid nitrogen heat exchanger4High purity CF in gas cylinders4The gas is liquefied. The liquid nitrogen heat exchanger consists of a low-temperature container, a liquid nitrogen coil and a mixed insulating medium coil. One end of the liquid nitrogen coil is connected with a liquid nitrogen storage tank, and the other end of the liquid nitrogen coil is emptied; one end of the mixed insulating medium coil is connected with a high-purity nitrogen cylinder and high-purity CF4And the other end of the gas cylinder is connected with a mixed insulating medium storage tank, and the mixed insulating medium coil is cooled by a liquid nitrogen coil. And a liquid inlet valve and an exhaust valve are respectively arranged at two ends of the liquid nitrogen coil pipe, and an air inlet valve and a liquid outlet valve are respectively arranged at two ends of the mixed insulating medium coil pipe. Nitrogen cylinder and CF4The gas output of the gas cylinder is controlled by respective pressure reducing valves, and the high-purity nitrogen and the high-purity CF4The proportion of gas is determined by electronic scale weighing or gas chromatograph measurement. The liquid outlet pipe of the mixed insulating medium is connected to a mixed insulating medium storage tank, the mixed insulating medium storage tank is a low-temperature closed container, and a vacuum valve and a liquid inlet valve are arranged at the top of the low-temperature closed container. Firstly, a closed container is vacuumized to a vacuum state below 0.1Pa by a vacuum unit, and then mixed with an insulating mediumThe liquid passing through the liquid inlet pipe flows into the insulating medium storage tank.
The second method comprises the following steps:
using refrigerator with liquid nitrogen temperature zone to treat nitrogen and CF in nitrogen bottle4CF in gas cylinders4The gas is liquefied. The refrigerating machine of liquid nitrogen temperature zone is composed of compressor and cold head, and the cold head of refrigerating machine can be used for refrigerating nitrogen and CF4The gas is cooled. Nitrogen cylinder and CF4The gas output of the gas cylinder is controlled by respective pressure reducing valves, and the high-purity nitrogen and the high-purity CF4The proportion of gas is determined by electronic scale weighing or gas chromatograph measurement. High-purity nitrogen cylinder and high-purity CF4The gas of the gas cylinder is connected to a mixed insulating medium storage tank through a gas outlet pipe, the mixed insulating medium storage tank is a low-temperature closed container, and the top of the low-temperature closed container is provided with a vacuum valve and a gas inlet valve; the cold head of the refrigerator is arranged on the top of the mixed insulating medium storage tank, firstly, the closed container is vacuumized to be below 0.1Pa by a vacuum unit, and then nitrogen and CF are added4The gas flows into the insulating medium storage tank through the gas inlet pipe, and is stored in the storage tank after being condensed by the cold head of the refrigerating machine.
Compared with other methods, the method has the following advantages:
(1) the mixed insulating medium has low cost, the lowest freezing point can reach about 52K, the insulating capability of the mixed insulating medium is much higher than that of low-temperature liquid such as liquid helium, liquid neon and the like, the mixed insulating medium can be conveniently used for cooling superconducting electrical equipment in a temperature region below 55K-65K liquid nitrogen, and the mixed insulating medium has important significance for the miniaturization and cost reduction of the superconducting electrical equipment.
(2) The boiling point of the mixed insulating medium can reach about 145K at most, the mixed insulating medium can be conveniently used for cooling electrician equipment in a 90K-120K liquefied natural gas temperature region, and the mixed insulating medium has important significance for development and popularization of the electrician equipment in the liquefied natural gas temperature region.
Drawings
FIG. 1 is N2And CF4The solid-liquid phase equilibrium diagram of (1);
FIG. 2 is N2And CF4Gas-liquid phase equilibrium diagram of (a);
FIG. 3 is a graph showing the variation of critical current of YBCO superconducting tape with temperature and magnetic field;
FIG. 4 is a schematic diagram of a method for preparing a mixed insulating medium by using a liquid nitrogen heat exchanger according to embodiment 1 of the present invention;
fig. 5 is a schematic diagram of a method for preparing a mixed insulating medium by using a refrigerator according to embodiment 2 of the present invention.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
The purity of the nitrogen and the purity of the carbon tetrafluoride gas adopted by the mixed insulating medium are both more than or equal to 99 percent. Mixing insulating media different liquid nitrogen and liquefied carbon tetrafluoride (CF)4) The proportional freezing point, bubble point and dc withstand voltage parameters are shown in table 1. The mixed liquid insulating medium can not only reach the insulating strength equivalent to that of liquid nitrogen, but also meet the engineering application requirements of 55K-145K at the liquefaction temperature.
Example 1
Liquid nitrogen at 90% molar ratio and liquefied CF at 10% molar ratio4Preparing the mixed insulating medium. Method for treating high-purity nitrogen and high-purity CF by adopting liquid nitrogen heat exchanger4Liquefaction is carried out. The freezing point of the prepared mixed insulating medium is 59K, the normal-pressure bubble point is 78K, and the direct-current withstand voltage is more than 10 kV/mm. The preparation method specifically comprises the following steps:
high-purity nitrogen and CF in nitrogen bottle by using liquid nitrogen heat exchanger4High purity CF in gas cylinders4The gas is liquefied. The liquid nitrogen heat exchanger consists of a low-temperature container, a liquid nitrogen coil and a mixed insulating medium coil. One end of the liquid nitrogen coil is connected with a liquid nitrogen storage tank, and the other end of the liquid nitrogen coil is emptied; one end of the mixed insulating medium coil is connected with a high-purity nitrogen cylinder and high-purity CF4And the other end of the gas cylinder is connected with a mixed insulating medium storage tank, and the mixed insulating medium coil is cooled through a liquid nitrogen coil. Liquid inlet valves and emptying valves are arranged at two ends of the liquid nitrogen coil pipe, and air inlet valves and liquid outlet valves are arranged at two ends of the mixed insulating medium coil pipe. Passing through a high purity nitrogen cylinder and high purity CF4The pressure reducing valve of the gas cylinder controls the gas output. Determination of high purity nitrogen and high purity CF by electronic scale weighing or gas chromatograph measurement4The ratio of gas. The liquid outlet pipe of the mixed insulating medium is connected to the mixed insulating mediumThe storage tank is a low-temperature closed container, and a vacuum valve and a liquid inlet valve are arranged at the top of the low-temperature closed container. Firstly, the closed container is vacuumized to be below 0.1Pa, and the mixed insulating medium flows into the insulating medium storage tank through the liquid inlet pipe.
Example 2
Liquid nitrogen at 80% molar ratio and liquefied CF at 20% molar ratio4Preparing the mixed insulating medium. The freezing point of the prepared mixed insulating medium is 57K, the normal-pressure bubble point is 78K, and the direct-current withstand voltage is more than 10 kV/mm. Refrigerating machine using liquid nitrogen temperature zone for high-purity nitrogen and high-purity CF4Liquefaction is carried out as follows:
the refrigerating machine of liquid nitrogen temperature zone is composed of compressor and cold head, and the cold head of refrigerating machine can be used for refrigerating nitrogen and CF4The gas is cooled. Pressure reducing valve of high-purity nitrogen cylinder and high-purity CF4The pressure reducing valve of the gas cylinder controls the gas output of the gas cylinder. High purity nitrogen and high purity CF4The proportion of gas is determined by weighing with an electronic scale or by measurement with a gas chromatograph. High-purity nitrogen cylinder and high-purity CF4The gas of the gas cylinder is connected to the mixed insulating medium storage tank through a gas outlet pipe. The mixed insulating medium storage tank is a low-temperature closed container, and the top of the low-temperature closed container is provided with a vacuum valve and an air inlet valve. The cold head of the refrigerator is arranged on the top of the mixed insulating medium storage tank. First, a closed container is vacuumized to below 0.1Pa, and nitrogen and CF are added4The gas flows into the insulating medium storage tank through the gas inlet pipe, and is stored in the storage tank after being condensed by the cold head of the refrigerating machine.
Example 3
Liquid nitrogen at 60% molar ratio and liquefied CF at 40% molar ratio4Preparing the mixed insulating medium. The freezing point of the prepared mixed insulating medium is 54K, the normal-pressure bubble point is 79K, and the direct-current withstand voltage is more than 10 kV/mm. High-purity nitrogen and high-purity CF by liquid nitrogen heat exchanger method4Liquefaction is carried out.
Example 4
Liquid nitrogen at 50% molar ratio and liquefied CF at 50% molar ratio4Preparing the mixed insulating medium. The freezing point of the prepared mixed insulating medium is 58K, the normal-pressure bubble point is 81K, and the direct-current withstand voltage is more than 10 kV/mm. Using warm zones of liquid nitrogenRefrigerator method for high-purity nitrogen and high-purity CF4Liquefaction is carried out.
Example 5
Liquid nitrogen at 40% molar ratio and liquefied CF at 60% molar ratio4Preparing the mixed insulating medium. The freezing point of the prepared mixed insulating medium is 62K, the normal-pressure bubble point is 82K, and the direct-current withstand voltage is more than 10 kV/mm. Method for treating high-purity nitrogen and high-purity CF by adopting liquid nitrogen heat exchanger4Liquefaction is carried out.
Example 6
Liquid nitrogen at 20% molar ratio and liquefied CF at 80% molar ratio4Preparing the mixed insulating medium. The freezing point of the prepared mixed insulating medium is 74K, the normal-pressure bubble point is 89K, and the direct-current withstand voltage is more than 10 kV/mm. Method for treating high-purity nitrogen and high-purity CF by using refrigerating machine with liquid nitrogen temperature zone4Liquefaction is carried out.
Example 7
Liquid nitrogen at 10% molar ratio and liquefied CF at 90% molar ratio4Preparing the mixed insulating medium. The freezing point of the prepared mixed insulating medium is 81K, the normal-pressure bubble point is 97K, and the direct-current withstand voltage is more than 10 kV/mm. High-purity nitrogen and high-purity CF by adopting liquid nitrogen heat exchanger4Liquefaction is carried out.
Example 8
Liquid nitrogen at 2% molar ratio and liquefied CF at 98% molar ratio4Preparing the mixed insulating medium. The freezing point of the prepared mixed insulating medium is 89K, the normal-pressure bubble point is 121K, and the direct-current withstand voltage is more than 10 kV/mm. Method for treating high-purity nitrogen and high-purity CF by using refrigerating machine with liquid nitrogen temperature zone4Liquefaction is carried out.
TABLE 1
Claims (3)
1. A mixed insulating medium of liquid nitrogen and liquefied carbon tetrafluoride is characterized in that: the mixed insulating medium is prepared from nitrogen with the purity of more than or equal to 99 percent and carbon tetrafluoride gas with the purity of more than or equal to 99 percent; the proportion of the liquid nitrogen to the liquefied carbon tetrafluoride is (2-90%): (98-10%) as a molar ratio; the molar ratio of liquid nitrogen to liquefied carbon tetrafluoride is (45% -90%): (55-10%) the freezing point of the prepared mixed insulating medium can be regulated to 52-60K, and the cooling requirement of electrical equipment in a temperature region below liquid nitrogen is met; the molar ratio of liquid nitrogen to liquefied carbon tetrafluoride is (2-20%): (98% -80%) under the condition, the normal pressure bubble point of the prepared mixed insulating medium can be regulated to 89K-121K, and the cooling requirement of electrical equipment in a liquefied natural gas temperature region is met; the DC withstand voltage of the prepared mixed insulating medium is more than 10 kV/mm.
2. The method of formulating a hybrid insulation medium of claim 1, wherein: high-purity nitrogen and CF in nitrogen bottle by using liquid nitrogen heat exchanger4High purity CF in gas cylinders4Liquefying the gas; the liquid nitrogen heat exchanger is composed of a low-temperature container, a liquid nitrogen coil and a mixed insulating medium coil, and the mixed insulating medium coil is cooled by the liquid nitrogen coil; a liquid inlet valve and an emptying valve are respectively arranged at two ends of the liquid nitrogen coil pipe, and an air inlet valve and a liquid outlet valve are respectively arranged at two ends of the mixed insulating medium coil pipe; nitrogen cylinder and CF4The gas output of the gas cylinder is controlled by respective pressure reducing valves, and the high-purity nitrogen and the high-purity CF4The proportion of gas is determined by weighing with an electronic scale or measuring with a gas chromatograph; the liquid outlet pipe of the mixed insulating medium is connected to a mixed insulating medium storage tank, the mixed insulating medium storage tank is a low-temperature closed container, and the top of the mixed insulating medium storage tank is provided with a vacuum valve and a liquid inlet valve; firstly, a mixed insulating medium storage tank is vacuumized to a vacuum state below 0.1Pa through a vacuum unit, and the mixed insulating medium flows into the insulating medium storage tank through a liquid inlet pipe.
3. The method of formulating a hybrid insulation medium of claim 1, wherein: high-purity nitrogen and CF in nitrogen bottle by using refrigerator with liquid nitrogen temperature zone4High purity CF in gas cylinders4Liquefying the gas; the refrigerating machine of liquid nitrogen temperature zone is composed of compressor and cold head, and the cold head of refrigerating machine can be used for refrigerating nitrogen and CF4Cooling the gas; nitrogen cylinder and CF4The gas output of the gas cylinder is controlled by respective pressure reducing valves, and the high-purity nitrogen and the high-purity CF4The proportion of gas is determined by weighing with an electronic scale or measuring with a gas chromatograph; nitrogen cylinder and CF4The gas of the gas cylinder is connected to a mixed insulating medium storage tank through a gas outlet pipe, the mixed insulating medium storage tank is a low-temperature closed container, and the top of the mixed insulating medium storage tank is provided with a vacuum valve and a gas inlet valve respectively; the cold head of the refrigerator is arranged at the top of the mixed insulating medium storage tank; firstly, a mixed insulating medium storage tank is vacuumized to a vacuum state below 0.1Pa by a vacuum unit, and nitrogen and CF are4The gas flows into the insulating medium storage tank through the gas inlet pipe, and is stored in the storage tank after being condensed by the cold head of the refrigerating machine.
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| CN111627684B (en) * | 2020-05-07 | 2022-03-08 | 中国科学院电工研究所 | Superconducting current-limiting transformer cooled by using liquid nitrogen and fluorocarbon mixed liquid insulating medium |
| CN112327110B (en) * | 2020-10-19 | 2024-06-14 | 中国科学院电工研究所 | Wide-temperature-zone liquid medium environment test device based on conduction cooling of refrigerator |
| CN112712958B (en) * | 2020-12-23 | 2023-01-31 | 中国科学院电工研究所 | High-temperature superconducting magnet cooled by liquid nitrogen shielding mixed liquid medium |
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| US6041621A (en) * | 1998-12-30 | 2000-03-28 | Praxair Technology, Inc. | Single circuit cryogenic liquefaction of industrial gas |
| US6374617B1 (en) * | 2001-01-19 | 2002-04-23 | Praxair Technology, Inc. | Cryogenic pulse tube system |
| CN1204222C (en) * | 2002-05-14 | 2005-06-01 | 中国科学院理化技术研究所 | Multi-component mixture working medium throttling refrigerant suitable for cryogenic temperature zone |
| CN102136311A (en) * | 2010-11-10 | 2011-07-27 | 中国科学院电工研究所 | Mixed gas insulating medium |
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