Large-scale storage, rapid liquefaction and recovery device for high-purity gas

Abstract

A large-scale storage, rapid liquefaction and recovery device for high-purity gas. By taking advantage of the characteristic that the saturated vapor pressure of a gas rapidly decreases as the temperature drops below the critical point, it fully exploits the ultimate performance of gas cylinders, gear pumps, refrigeration devices, and heaters, integrates existing standardized gas cylinders, gear pumps, and refrigeration devices to achieve the purpose of high-density storage, rapid liquefaction, and recovery, and can be used in the field of high-purity gas usage with a scale of dozens of tons or hundreds of tons.

Description

Technical Field

[0001] The present invention relates to the field of use of high-purity fluid media or expensive fluid media, and specifically to a device for large-scale storage, rapid liquefaction and recovery of high-purity gas. Background Art

[0002] Direct detection of dark matter is a frontier topic in the field of high-energy physics experiments. Currently, the mainstream detectors at home and abroad use cryogenically liquefied high-purity xenon as the target substance. The scale of the detectors has gradually developed from the initial 10 kg level to the current 10-ton level. For example, experiments such as the PandaX, XENON, and LZ (LUX) series. The detectors planned in the long term have reached the 100-ton level, and the detection target has also been extended to the search for neutrinoless double beta decay events. Such experiments must be carried out in deep underground laboratories to avoid interference from cosmic rays. However, the construction period of deep underground laboratories is long, the cost is high, and the space is relatively limited. With the expansion of the experimental scale, the equipment size must also be considered as a restrictive condition in the system design. Xenon is an expensive and rare noble gas, accounting for about 0.1 ppm in the air, and the global production capacity is also very limited. A huge amount of xenon gas needs to be accumulated for many years to meet the experimental scale. Moreover, the purity requirement of xenon gas for dark matter detection experiments reaches the 6N level, and the krypton content needs to be lower than 1 ppt or even 0.1 ppt. Therefore, xenon gas must be recycled and reused. In previous dark matter detection experiments, xenon was stored, filled, and recovered in the form of gaseous xenon. The filling and recovery processes were accompanied by gas-liquid phase changes, and even the recovery process required multiple phase changes, resulting in serious energy waste, low operation efficiency, and a large consumption of liquid nitrogen. Now it has been upgraded to stainless steel dewars for recovery, filling, and storage, but this solution still occupies a large area and is expensive. For example, the XENON1T experimental group designed a ReStoX system for storing, filling, and recovering liquid xenon. Among them, a vacuum-insulated spherical tank with a diameter of 2.1 m can store 7.6 tons of xenon. However, the cooling process requires a large amount of liquid nitrogen, and the system also needs to be equipped with a liquid nitrogen tank with a volume of 10 m 3 . Liquid xenon detectors generally operate at 178 K, while the boiling point of liquid nitrogen is 77 K, and the temperature difference between the two is huge, resulting in low cold energy utilization efficiency. In ground-based experiments where liquid nitrogen is supplied on a large scale, this problem is not serious, but it is different in underground laboratories. Since the coefficient of performance decreases with the decrease of the refrigeration temperature, it is extremely inefficient to produce liquid nitrogen in the laboratory and use it to cool and liquefy xenon gas, and the production equipment also occupies precious space. Transporting a large amount of liquid nitrogen from the outside to the underground laboratory requires a large amount of human resources. The aforementioned contradictions have become increasingly prominent with the expansion of the experimental scale. Therefore, it is necessary to develop a technology for large-scale, high-density storage, rapid liquefaction and recovery of high-purity xenon gas that does not rely on a large amount of liquid nitrogen.

[0003] The present invention fully exploits the various extreme performances of existing standard gas cylinders and gear pumps to obtain the ability to store high-purity xenon gas in a high-density and large-scale manner, and to ensure high-speed recovery, liquefaction and perfusion, etc. Summary of the Invention

[0004] The present invention aims to solve the problems of large floor space, high storage cost, and difficulty in rapid liquefaction and rapid recovery in the large-scale storage of existing high-purity gases. The present invention provides a device for large-scale storage, rapid liquefaction, and recovery of high-purity gases. In particular, by utilizing the characteristics that the critical temperature of xenon is close to room temperature and the saturated vapor pressure rapidly decreases with the decrease of temperature below the critical point, the ultimate performance of gas cylinders, gear pumps, refrigeration devices, and heaters is fully exploited, and the existing standardized steel gas cylinders, gear pumps, and refrigeration devices are integrated to achieve the purpose of high-density storage and rapid liquefaction and recovery, which can be used in the future fields of high-purity xenon gas usage of dozens of tons or hundreds of tons.

[0005] The technical solution of the present invention is as follows:

[0006] A device for large-scale storage, rapid liquefaction, and recovery of high-purity gases, characterized by comprising a storage gas cylinder group, a filling pipeline, a liquid xenon recovery pipeline, and a liquid xenon emergency recovery pipeline.

[0007] The storage gas cylinder group includes a gas cylinder group frame and a gas cylinder group. The gas cylinder group frame is a heat-insulated structural cavity composed of a frame and a heat-insulating layer. The gas cylinder group includes an upper tray, a lower tray, and N gas cylinders. Upper heat exchangers, upper electric valves, lower heat exchangers, and lower electric valves are respectively provided at the shoulders at the upper and lower ends of each gas cylinder and are placed between the upper tray and the lower tray. The gas cylinder group is placed in the heat-insulated structural cavity within the gas cylinder group frame. A weighing sensor is provided below the lower tray. The upper tray is provided with an upper pipeline and an upper secondary coolant pipeline connected to the upper end of each gas cylinder. The lower tray is provided with a lower pipeline and a lower secondary coolant pipeline connected to the lower end of each gas cylinder. All N gas cylinders are vertically arranged within the gas cylinder group frame; where N is a positive integer greater than or equal to 2.

[0008] The upper pipeline is connected and communicated with an external high-pressure gas cylinder through a first pressure reducing valve and a first electric valve in sequence during the filling working condition; is connected and communicated with the outlet of a first electric heater during the normal recovery working condition; and is connected and communicated with the hot-side inlet end of a third heat exchanger during the emergency recovery working condition.

[0009] The lower pipeline is connected to the 1st port of the PandaX detector through the pipeline in sequence with the 2nd electric valve, intermediate heat exchanger, 1st gear pump, 1st buffer, end heat exchanger, 2nd gear pump, 2nd buffer, 3rd electric valve, and 3rd gear pump under the filling condition. A 1st pressure sensor is provided on the lower pipeline before the 2nd electric valve, a 2nd pressure sensor is provided on the 1st buffer, a 3rd pressure sensor is provided on the 2nd buffer, and a 2nd xenon pipeline is provided on the second buffer. The 2nd xenon pipeline is connected to the 2nd port of the PandaX detector through the 4th electric valve and the 2nd pressure reducing valve in sequence; a 1st xenon pipeline is provided on the 1st buffer, and the 1st xenon pipeline is connected to the 3rd port of the PandaX detector through the 5th electric valve and the 3rd pressure reducing valve in sequence; the PandaX detector is also provided with a refrigeration system and a 4th pressure sensor; in the emergency recovery condition, the lower pipeline is connected and communicated with the outlet end of the 3rd electric heater after passing through the 2nd electric valve;

[0010] The liquid xenon recovery pipeline includes a 1st thermometer, a 1st electric heater, a 2nd thermometer, and a 2nd electric heater in sequence. The two ends of the liquid xenon recovery pipeline are respectively connected to the upper pipeline and the 3rd port of the 3rd electric valve;

[0011] The liquid xenon emergency recovery pipeline includes a 3rd electric heater, a 3rd temperature sensor, a 3rd heat exchanger, a 4th heat exchanger, a 4th gear pump, and a pipeline. On the pipeline between the 3rd electric valve and the lower pipeline, the 3rd electric valve is connected to the 1st port of the 4th heat exchanger. The 2nd port of the 4th heat exchanger is connected to one end of the 3rd electric heater. The other end of the 3rd electric heater and one end of the 2nd electric valve are connected. The 4th gear pump is connected between the 4th port and the 1st port of the 4th heat exchanger. A 3rd temperature sensor is provided on the pipeline between the 3rd electric heater and the 2nd electric valve; the two ends of the 3rd heat exchanger are respectively connected to the upper pipeline and the 3rd port of the 4th heat exchanger;

[0012] The intermediate heat exchanger and the end heat exchanger are also respectively connected to the first chiller and the second chiller, or are respectively the evaporators of the first chiller and the second chiller.

[0013] The design pressure of the gas cylinder is not less than 10 MPa.

[0014] The gas cylinder and equipment such as valves inside the thermal insulation structure can work at a temperature of -30°C and below for a long time; the gaseous xenon or liquid xenon output by the gas cylinder has a temperature between -40°C and -30°C.

[0015] The described thermal insulation structure is composed of a material with low thermal conductivity or is made of vacuum insulation. The thermal conductivity of the material with low thermal conductivity is not greater than 0.1 W / (m·K), the thickness is not less than 50 mm, the total area is not less than the surface area of a single gas cylinder, and the effective thermal conductance of the thermal insulation structure is not greater than 20 W / K.

[0016] The described gas cylinder temperature control structure is made of copper, aluminum or other materials with a thermal conductivity not less than 100 W / (m·K). It has a heat exchange fluid passage inside, and there are at least 2 inlet pipes and outlet pipes for the heat exchange fluid. The temperature control structure and the cylinder body of the gas cylinder are closely matched through thermal conductive glue. The matching area is not less than 50 square centimeters, and the average normal stress of the matching surface is not less than 1000 Pa.

[0017] The design pressure of the described heat exchanger, gear pump, buffer and electric valve is not less than 2 MPa, and they have a thermal insulation structure.

[0018] The described gear pump is a gear pump driven by a magnetic coupling without dynamic seal. The driving motor of the gear pump is a stepper motor or a servo motor that can be adjusted in speed and can rotate forward and backward.

[0019] The described refrigerator is a self - cascading refrigerator. The evaporator of the refrigerator has two sets. One set is used to cool the secondary refrigerant, and the other set can directly cool the high - purity gas. The secondary refrigerant is anhydrous ethanol.

[0020] In an emergency, the gas cylinder can be cooled by the recycled cryogenic liquid through the heat exchanger and the gear pump. The cryogenic liquid enters from the bottom of the gas cylinder. During the process of cooling the cylinder body, part or all of the cryogenic liquid vaporizes, and the vaporized gas is discharged from the upper valve of the gas cylinder. Then it enters the heat exchanger through the upper pipeline to exchange heat and condense with the cryogenic liquid from the detector, and is then pumped into the same pipeline for mixing through the gear pump.

[0021] In the present invention, some gear pumps and pipelines can also be used for the cyclic purification of high - purity gas / liquid. There are a fourth pipeline and a fifth pipeline connected to the third electric valve. Liquid xenon enters the liquid purifier through the fourth pipeline, is purified and then enters the seventh pipeline. There is a first electric flow regulating valve between the seventh pipeline and the eighth pipeline. The eighth pipeline is connected to the fourth port of the detector, and the purified liquid xenon enters the detector from here. The fourth pipeline is connected to the cold - side inlet of the fifth heat exchanger, the cold - side outlet is connected to the inlet of the gas purifier, the outlet of the gas purifier is connected to the hot - side inlet of the fifth heat exchanger, the hot - side outlet of the fifth heat exchanger is connected to the sixth pipeline, and there is a second electric flow regulating valve between the sixth pipeline and the eighth pipeline. The fifth heat exchanger is used to recover the cold energy of the liquid xenon entering the gas purifier, so as to reduce the demand of the detector system for the refrigeration system and also reduce the heating demand of the gas purifier. The heat introduced during the purification process is cooled by the refrigeration system of the detector. The xenon flow rates of the liquid purifier and the gas purifier can be adjusted by two electric flow regulating valves respectively.

[0022] Gas cylinders designed, manufactured, inspected and accepted in accordance with the national standard GB / T 33145 "Large-volume seamless steel gas cylinders" and supervised by the TSG R0006 "Safety Technical Supervision Regulations for Gas Cylinders" have extremely mature production technology and are mass-produced, so their costs have been compressed to the limit compared with other pressure vessels. The gas cylinder with the model number TUBE 1-559-1065-20 has a rated working pressure of 20 MPa, that is, the pressure of the filling medium shall not exceed 20 MPa. The maximum hydrostatic test pressure can reach 33.4 MPa, and the bursting pressure is 50 MPa. The diameter of the gas cylinder is 559 mm, the length is about 5100 mm, and the weight is about 1370 kg. The material grade used is 4130X. The operating temperature range of this gas cylinder is -40°C to 60°C, that is, 233K to 333K. The critical temperature of xenon is 290K, and the critical pressure is 5.84 MPa. Near this operating condition, the saturated vapor pressure of xenon is closely related to the temperature. As the temperature drops, the saturated vapor pressure drops rapidly. At 238K, the saturated vapor pressure is 1.8 MPa. We can fully exploit the ultimate pressure and ultimate operating temperature of this gas cylinder to obtain a large-scale high-density storage system that meets our requirements. The highest output pressure of the existing gear pump without dynamic seal is 2.5 MPa, and the lowest operating temperature is -150°C. The following takes the gas cylinder with the model number TUBE 1-559-1065-20 as an example to illustrate the design concept of the present invention.

[0023] The highest operating temperature of the gas cylinder is 333K, and the maximum operating pressure of the gas cylinder is 20 MPa. The supercritical xenon density corresponding to this operating condition is 1773 kg / m 3 , so the filling density of the gas cylinder should not exceed 1773 kg / m 3 . When the normal room temperature is 298K, the corresponding pressure does not exceed 10 MPa. The filling coefficient in the present invention is rounded down and determined to be 1750 kg / m 3 .

[0024] Multiple steel gas cylinders containing xenon gas can be placed together in a steel structure frame to form a gas cylinder group. There is thermal insulation material around the frame. The gas cylinders are placed vertically, and heat exchangers are closely fitted to the upper and lower shoulders of the gas cylinders to enable the gas cylinders to operate at the desired temperature and facilitate the fixing of the gas cylinders. There are coolant channels in the heat exchangers, which can efficiently transfer the cold quantity of the coolant to the gas cylinders to cool the gas cylinders. The gas cylinders can also be heated with a coolant at +58°C.

[0025] For xenon gas with the same density, the saturated vapor pressure decreases as the temperature drops. Therefore, when recovering xenon, we choose to operate the gas cylinder and its internal medium near 238K. At this time, the saturated vapor pressure of xenon is lower than 1.8MPa, much lower than the storage pressure at room temperature, which can reduce the pressure requirement for the medium transfer pump. At the gas-liquid equilibrium at 238K, the saturated vapor pressure of xenon is lower than 1.8MPa, and the density of liquid xenon is about 2358kg / m 3 , and the specific enthalpy of liquid xenon is 27kJ / kg; at 243K, the saturated vapor pressure of xenon is about 2MPa, the density of liquid xenon is 2317kg / m 3 , and the specific enthalpy of liquid xenon is 29kJ / kg. The specific enthalpy of xenon at the critical state of 5.83Mpa and 290K is 68kJ / kg, and the specific enthalpy of xenon at a pressure of 0.5Mpa and room temperature of 290K is 115kJ / kg. The required temperature of xenon for the detector is 178K, the saturated vapor pressure is 0.2MPa, and the specific enthalpy of liquid xenon is 4.4kJ / kg. It can be seen that at the same temperature, the specific enthalpy of high-density xenon is lower. And as the temperature drops, the specific enthalpy of xenon also decreases rapidly. The specific enthalpy of liquid xenon at the gas-liquid equilibrium state of 238K has decreased by more than half compared to the critical state. For a gas cylinder with a filling coefficient of 1750kg / m 3 , when cooled to 238K, the density of liquid xenon is 2358kg / m 3 , the density of gaseous xenon is 154kg / m 3 . From this, it can be obtained that in a 1000L gas cylinder, there is 724L of liquid xenon, 1708kg, and about 276L of gaseous xenon, 42kg, accounting for only 2.4%. It can be seen that most of the xenon has been liquefied, and it is reasonable to neglect gaseous xenon in thermodynamic calculations. Directly precooling the high-pressure stored xenon gas to 238K can greatly reduce the demand for refrigeration capacity for filling xenon into the detector.

[0026] When filling xenon gas / liquid xenon in the gas cylinder into the particle detector, it needs to be cooled to the target temperature of 178K. The specific enthalpy of xenon with a density of 1.75kg / L at 298K is about 53kJ / kg, the specific enthalpy of liquid xenon at the gas-liquid equilibrium at 238K is 27kJ / kg, and the enthalpy of liquid xenon at 178K is 4.4kJ / kg. In other words, when xenon stored at room temperature is filled into the detector, the refrigeration capacity required for xenon is 48.6kJ / kg, while the refrigeration capacity required for xenon precooled to 238K is 22.6kJ / kg, about half of the total refrigeration capacity. And this part of the pre-cooling work can be carried out during the installation preparation stage of the detector. There is at least 10 days or even dozens of days, and the required refrigeration power is small. The refrigeration equipment at low temperature has high refrigeration efficiency and is also relatively cheap. The gas cylinder storing xenon gas also needs to be cooled synchronously. The weight of the gas cylinder is about 1370kg, and the specific heat capacity is about 500J / (kg·K). From 298K to 238K, the total required refrigeration amount is 4×10 7J. When converted to xenon, the additional cooling capacity required per kg of xenon is 23.5 kJ / kg. The equivalent cooling capacity required to cool the xenon in the gas cylinder from 298 K to 238 K is 49 kJ / kg.

[0027] The cooling capacity required to cool the liquid xenon at 238 K to 178 K is 22.6 kJ / kg, that is, the filling rate that can be obtained by a cryogenic refrigerator at 178 K is 0.044 kg / (s·kW), or 3823 kg / (day·kW). For detectors in the order of dozens or even hundreds of tons, this filling rate is still too small. Or rather, to increase the filling rate, a cryogenic refrigerator with a refrigeration power of about 10 kW is required, and such a cryogenic refrigerator is too large.

[0028] If this cooling is further divided into two stages, the primary stage cools from 238 K to 208 K, and the specific enthalpy of liquid xenon is 15 kJ / kg. The advanced stage cools from 208 K to 178 K. In this way, the cooling capacities required for the primary and advanced stages are 12 kJ / kg and 10.6 kJ / kg respectively. The filling rate obtained by the 178 K cryogenic refrigerator can be increased to 0.094 kg / (s·kW), or 8121 kg / (day·kW). A 178 K cryogenic refrigerator with a power of 3 kW can obtain a filling rate of about 25 tons / day, which is very fast for a detector in the order of hundreds of tons.

[0029] The technical gap between the refrigerators for outputting 238 K and 208 K is not large. And during the precooling process, the cooling capacity is transferred by the secondary coolant. In addition to the secondary coolant transferring the cooling capacity during the primary cooling, a direct-cooling heat exchanger can also be designed on the refrigerator to cool the high-purity gas in the direct heat exchanger to improve the cooling efficiency. The refrigerators for precooling and primary cooling can be combined into one to improve the utilization efficiency of the equipment and save the precious space in the underground laboratory and the investment in experimental equipment. Also, because the refrigeration efficiency decreases as the refrigeration target temperature drops, the temperature point for the relay between the shallow-temperature refrigerator and the cryogenic refrigerator can be appropriately lowered, and the power margin of the shallow-temperature refrigerator can be appropriately increased. Considering the efficiency, price, size, etc. of the refrigeration equipment as a whole, the system performance can be optimized.

[0030] When the liquid xenon is recycled to the gas cylinder group, in order to obtain a stable working pressure and ensure safety and reliability, the gas cylinder needs to be precooled to 238 K. When recycling the liquid xenon, the liquid xenon at 178 K needs to be heated to 238 K to prevent the temperature of the gas cylinder from being lower than 233 K. At this time, the heating amount required for the liquid xenon is 22.6 kJ / kg. If the recycling rate is calculated at 25 tons / day, the required heating power is 6.5 kW, which is very easy for an electric heater.

[0031] In the case of planned recovery operations, there is sufficient time to precool the gas cylinder group. In the case of unplanned recovery, the gas cylinder group may not have been cooled to 238K yet. However, liquid xenon at 178K can be used to cool the gas cylinder group. The enthalpy difference between 1750 kg of liquid xenon at 178K - 0.2MPa and liquid xenon at 238K - 1.77MPa is 4.2×10 7 J. For a 1370 kg steel gas cylinder, the refrigeration capacity required to cool it from 298K to 238K is 4.11×10 7 J, slightly less than the enthalpy difference required for xenon heating. During the recovery process, a small amount of refrigeration capacity can be supplemented by the primary refrigerator. Therefore, from an energy perspective, it is feasible to use the liquid xenon in the detector to cool the air cylinder group at room temperature. The heat leakage power of the gas cylinder group module decreases with the decrease of the temperature difference. Considering the supply reliability of 5℃ cold water in the underground laboratory and the cooling power in the order of 100 kw, it is feasible to maintain the gas cylinder group at 278K for a long time. The refrigeration capacity required to cool a single gas cylinder to 238K is 2.74×10 7 J. Even with the heat leakage of the recovery system added, there is sufficient cooling margin. Therefore, the cold energy of low-temperature liquid xenon can be transferred to the gas cylinder by using a heat exchanger, and it is ensured that the temperature of the gas cylinder or a local area of the gas cylinder is not lower than 233K at any time.

[0032] After the liquid xenon recovery is completed, a small amount of residual xenon gas in the detector and pipeline can be recovered by soaking a stainless steel gas cylinder in liquid nitrogen.

[0033] During the operation of the detector, some gear pumps and pipelines can also be used as part of the high-purity gas / liquid circulation system to improve the equipment utilization rate.

[0034] Compared with the existing technology, the technical advantages of the present invention are as follows:

[0035] 1. Make full use of the ultimate working pressure and ultimate working temperature of national standard gas cylinders, reduce the storage pressure of high-purity gas in the recovery stage, greatly reduce the technical requirements for pressurization equipment such as pumps and compressors, and have a wider selection range of general equipment for the design and manufacture of the storage system; improve the storage density of high-purity gas and the space utilization rate;

[0036] 2. Replace the customized stainless steel pressure vessel with a batch-produced standard steel gas cylinder, reduce the storage cost and improve the reliability;

[0037] 3. Adopt the precooling and stepwise cooling methods to cool the high-purity medium, reduce the power demand for refrigeration equipment, and also greatly reduce the demand for liquid nitrogen;

[0038] 4. Use a gear pump that can transmit bidirectionally as a pressurization device, simplify the pipelines and valves required for medium filling and recovery, and can also be used as a circulation pump for pure chemical processes;

[0039] 5. In the emergency recovery condition, the gas cylinder can be indirectly precooled by a cryogenic fluid medium. Brief Description of the Drawings

[0040] Figure 1 It is a schematic structural diagram of the gas cylinder group of the present invention.

[0041] Figure 2 It is a schematic connection structure diagram of the gas cylinder and the lower tray of the present invention.

[0042] Figure 3 It is a schematic structural diagram of the upper heat exchanger of the present invention.

[0043] Figure 4 It is a schematic diagram of the liquid xenon filling pipeline of the present invention.

[0044] Figure 5 It is a schematic diagram of the liquid xenon recovery pipeline of the present invention.

[0045] Figure 6 It is a schematic diagram of the liquid xenon emergency recovery pipeline of the present invention.

[0046] Figure 7 It is a process flow diagram of the liquid xenon / gaseous xenon cycle purification of the present invention. Detailed Embodiment

[0047] The following will further describe the specific implementation of the present invention in conjunction with the drawings and embodiments, but the protection scope of the present invention should not be limited thereby.

[0048] First, please refer to Figure 1 , Figure 2 , Figure 3 , the large-scale storage, rapid liquefaction and recovery device for high-purity gas of the present invention includes a storage gas cylinder group, a liquid xenon recovery pipeline and a liquid xenon emergency recovery pipeline.

[0049] The storage gas cylinder group includes a gas cylinder group frame 1 and a gas cylinder group. The gas cylinder group frame 1 forms a heat-insulating structure cavity by a frame and a heat-insulating layer 8. The gas cylinder group includes an upper tray 2, a lower tray 4 and N gas cylinders 3. At the shoulders at the upper and lower ends of each gas cylinder 3, there are respectively provided an upper heat exchanger 22, an upper electric valve 24, a lower heat exchanger 25, and a lower electric valve 23 and placed between the upper tray 2 and the lower tray 4. The gas cylinder group is placed in the heat-insulating structure cavity within the gas cylinder group frame 1. One or more weighing sensors 5 are provided below the lower tray 4. The upper tray 2 is provided with an upper pipeline 6 connected to the upper end of each gas cylinder 3 and an upper coolant pipeline 7 connected to the upper heat exchanger 22. The lower tray 4 is provided with a lower pipeline 10 connected to the lower end of each gas cylinder 3 and a lower coolant pipeline 9 connected to the lower heat exchanger 25. All N gas cylinders 3 are arranged vertically within the gas cylinder group frame 1; where N is a positive integer greater than or equal to 2.

[0050] The upper pipeline 6 is connected and communicated with an external high-pressure gas cylinder 62 through a first pressure reducing valve 60 and a first electric valve 60 in sequence under the filling condition; it is connected and communicated with the outlet end of a first electric heater 72 under the normal recovery condition; and it is connected and communicated with the hot-side inlet end of a third heat exchanger 83 under the emergency recovery condition.

[0051] The lower pipeline 10 is connected to a first port of a PandaX detector 100 through a pipeline, a second electric valve 41, an intermediate heat exchanger 42, a first gear pump 43, a first buffer 44, a terminal heat exchanger 46, a second gear pump 47, a second buffer 48, a third electric valve 50, and a third gear pump 51 in sequence under the filling condition. A first pressure sensor 63 is provided on the lower pipeline 10 before the second electric valve 41. A second pressure sensor 45 is provided on the first buffer 44. A third pressure sensor 49 is provided on the second buffer 48. A second xenon pipeline 54 is provided on the second buffer 48. The second xenon pipeline 54 is connected to a second port of the PandaX detector 100 through a fourth electric valve 56 and a second pressure reducing valve 55 in sequence. A first xenon pipeline 59 is provided on the first buffer 44. The first xenon pipeline 59 is connected to a third port of the PandaX detector 100 through a fifth electric valve 58 and a third pressure reducing valve 57 in sequence. The PandaX detector 100 is also provided with a refrigeration system 52 and a fourth pressure sensor 53. Under the emergency recovery condition, the lower pipeline 10 is connected and communicated with the outlet end of a third electric heater 81 after passing through the second electric valve 41.

[0052] The liquid xenon recovery pipeline includes a first thermometer 71, a first electric heater 72, a second thermometer 73, and a second electric heater 74 in sequence. Both ends of the liquid xenon recovery pipeline are respectively connected to the upper pipeline 6 and a third port of the third electric valve 50.

[0053] The liquid xenon emergency recovery pipeline includes a third electric heater 81, a third temperature sensor 82, a third heat exchanger 83, a fourth heat exchanger 84, a fourth gear pump 85, and a pipeline 86. On the pipeline 86 between the third electric valve 50 and the lower pipeline 10, the third electric valve 50 is connected to a first port of the fourth heat exchanger 84. A second port of the fourth heat exchanger 84 is connected to one end of the third electric heater 81. The other end of the third electric heater 81 and one end of the second electric valve 41 are connected. The fourth gear pump 85 is connected between a fourth port and a first port of the fourth heat exchanger 84. A third temperature sensor 82 is provided on the pipeline between the third electric heater 81 and the second electric valve 41. Both ends of the third heat exchanger 83 are respectively connected to the upper pipeline 6 and a third port of the fourth heat exchanger 84.

[0054] The intermediate heat exchanger (42) and the end heat exchanger (46) are also respectively connected to the first chiller and the second chiller during the filling stage, or are respectively direct cooling evaporators of the first chiller and the second chiller.

[0055] In the present invention, some gear pumps and pipelines can also be used for the cyclic purification of high-purity gases / liquids. There are a fourth pipeline and a fifth pipeline connected to the third electric valve 50. Liquid xenon enters the liquid purifier 92 through the fourth pipeline, is purified and then enters the seventh pipeline 98. There is a first electric flow regulating valve 93 isolating between the seventh pipeline 98 and the eighth pipeline 99. The eighth pipeline is connected to the fourth port of the detector 100, and the purified liquid xenon enters the detector therefrom. The fourth pipeline 90 is connected to the cold-side inlet 94-1 of the fifth heat exchanger, and the cold-side outlet 94-2 is connected to the inlet of the gaseous purifier 95. The outlet of the gaseous purifier is connected to the hot-side inlet 94-3 of the fifth heat exchanger. The hot-side outlet 94-4 of the fifth heat exchanger is connected to the sixth pipeline 97. There is a second electric flow regulating valve 96 isolating between the sixth pipeline 97 and the eighth pipeline 99. The fifth heat exchanger 94 is used to recover the cold energy of the liquid xenon entering the gaseous purifier 95 to reduce the demand of the detector system for the refrigeration system. The heat introduced during the purification process is cooled by the refrigeration system of the detector. Due to the high thermal efficiency of the fifth heat exchanger 94, the heat introduced during the purification process is less. Since the output pressure and output flow rate of the third gear pump 51 are both large, a very high circulation rate can be obtained. The liquid purifier 92 and the gaseous purifier 95 can be used in parallel or separately, and their respective flow rates are regulated by the first electric flow regulating valve 93 and the second electric flow regulating valve 96 respectively.

[0056] The designed pressure of the gas cylinder 3 described above is not less than 10 MPa.

[0057] The gas cylinder 3 and equipment such as valves inside the described thermal insulation structure can work at a temperature of -30°C and below for a long time; the gaseous xenon or liquid xenon output from the gas cylinder 3 has a temperature between -40°C and -30°C.

[0058] The described thermal insulation structure is composed of a low-thermal-conductivity material or is made of vacuum insulation. The thermal conductivity of the low-thermal-conductivity material is not greater than 0.1 W / (m·K), the thickness is not less than 50 mm, the total area is not less than the surface area of a single gas cylinder, and the effective thermal conductivity of the thermal insulation structure is not greater than 20 W / K;

[0059] The temperature control structure of the gas cylinder 3 described above is made of copper, aluminum or other materials with a thermal conductivity not less than 100 W / (m·K). There is a heat exchange fluid passage inside, and there are at least two inlet pipes (22A) and outlet pipes (22B) for the heat exchange fluid. The temperature control structure is in close cooperation with the cylinder body of the gas cylinder (3) through a thermal conductive adhesive. The cooperation area is not less than 50 square centimeters, and the average normal stress of the cooperation surface is not less than 1000 Pa.

[0060] The design pressures of the heat exchanger, gear pump, buffer, and electric valve described above are not less than 2 MPa, and they have a heat preservation structure.

[0061] The gear pump described above is a gear pump driven by a magnetic coupling without dynamic seals, and the drive motor of the gear pump is an adjustable-speed, reversible stepper motor or servo motor.

[0062] The refrigerator is a self-cascade refrigerator. The evaporator of the refrigerator has two sets. One set is used to cool the secondary refrigerant, and the other set can directly cool the high-purity gas, that is, directly serve as the intermediate heat exchanger or the terminal heat exchanger; the secondary refrigerant is anhydrous ethanol.

[0063] In an emergency, the gas cylinder can be cooled by the recycled cryogenic liquid through the heat exchanger and gear pump. The cryogenic liquid enters from the bottom of the gas cylinder. After contacting the gas cylinder, all or part of the liquid vaporizes. The vaporized gas enters the heat exchanger to exchange heat with the recycled cryogenic liquid and condenses, and then is pumped through the gear pump and pressurized into the same pipeline for mixing.

[0064] The upper secondary refrigerant pipeline 7 is connected to the inlet pipeline 22A of the heat exchanger 22 on the upper side of the gas cylinder 3. The secondary refrigerant flows out from the outlet pipeline 22B after passing through the fluid channel in the heat exchanger 22, and then flows through other upper-side heat exchangers in sequence. The lower secondary refrigerant pipeline 9 is connected to the inlet pipeline 22A of the heat exchanger 25 (structurally identical to the heat exchanger 22) on the lower side of the gas cylinder 3. The secondary refrigerant flows out from the outlet pipeline 22B after passing through the fluid channel in the heat exchanger 25, and then flows through other lower-side heat exchangers 25 in sequence. The upper secondary refrigerant pipeline 7 and the lower secondary refrigerant pipeline 9 can be connected in parallel or in series.

[0065] The intermediate heat exchanger 42 is connected to the first refrigerator and is cooled by the secondary refrigerant output by the first refrigerator. The lowest output temperature of the first refrigerator is -65 °C, and the output temperature is continuously adjustable from 60 °C to -65 °C. The intermediate heat exchanger 42 of the present invention can also be the first evaporator of the first refrigerator, which can directly cool the high-purity gas (or in the liquid phase). The second evaporator of the first refrigerator can cool the secondary refrigerant. The secondary refrigerant can cool or heat the gas cylinder through the upper secondary refrigerant pipeline 7 or the lower secondary refrigerant pipeline 9, or meet other cooling requirements within the corresponding temperature range. The secondary refrigerant used is preferably anhydrous ethanol.

[0066] The terminal heat exchanger 46 is connected to the second refrigerator and is cooled by the refrigerant output by the second refrigerator. The minimum output temperature of the second refrigerator is lower than -95°C. Considering the universality of the second refrigerator, the output temperature is designed to be -115°C. In the present invention, the terminal heat exchanger 46 can also be the first evaporator of the second refrigerator, which can directly cool the high-purity gas (or in the liquid phase), and the second evaporator of the second refrigerator can cool the refrigerant, thereby improving the convenience of the second refrigerator for other needs. The refrigerant used is preferably anhydrous ethanol.

[0067] The design pressure of the gas cylinder (3) is not less than 10 MPa.

[0068] The gas cylinder 3 and valves and other equipment inside the thermal insulation structure can work at a temperature of -30°C or below for a long time; the gas xenon or liquid xenon output by the gas cylinder 3 has a temperature between -40°C and -30°C.

[0069] The insulation structure is made of low thermal conductivity material or vacuum insulation. The thermal conductivity of the low thermal conductivity material is not greater than 0.1 W / (m·K), the thickness is not less than 50 mm, the total area is not less than the surface area of ​​a single gas cylinder, and the thermal conductivity of the insulation structure is not greater than 20 W / K.

[0070] The heat exchanger 22 and the heat exchanger 25 of the gas cylinder 3 are made of copper, aluminum or other materials with a thermal conductivity of not less than 100W / (m·K), have a heat exchange fluid passage inside, and have at least two heat exchange fluid inlets and outlets. The temperature control structure and the bottle body of the gas cylinder 3 are closely matched through thermal conductive glue, the matching area is not less than 50 square centimeters, and the average normal stress of the matching surface is not less than 1000Pa.

[0071] The design pressure of the heat exchanger, gear pump, buffer container and electric valve is not less than 2MPa and has a heat preservation structure;

[0072] The gear pump is a gear pump driven by a magnetic coupling without a dynamic seal, and the driving motor of the gear pump is a stepping motor, a servo motor, etc. which can be adjusted in speed and can rotate forward and reverse.

[0073] Example 1 - Large-scale storage, rapid liquefaction and recovery device for high-purity xenon gas

[0074] like Figure 1As shown in the figure, the TUBE 1-559-1065-20 gas cylinder used in the gas cylinder group of the present invention has a diameter of 559 mm and a length of 5490 mm, which complies with the national standard GB / T33146-2016 and is supervised by the TSG R0006 "Gas Cylinder Safety Technical Supervision Regulations". The weight of a single gas cylinder is 1370 kg, the nominal volume is 1065 L, and the nominal pressure is 20 MPa. There are openings at both ends of the gas cylinder. For the gas cylinders used in the present invention, valves are designed at both ends, namely the upper electric valve 24 and the lower electric valve 23. The gas cylinder group frame 1 serves as the installation foundation for the gas cylinders and other structures, and at the same time provides protection for the gas cylinders and other structures. The upper tray 2 of the gas cylinder group and the lower tray 4 of the gas cylinder group are arranged in a 3×4 pattern with the gas cylinders 3. The upper tray 2 and the lower tray 4 provide horizontal constraints for the gas cylinders 3 and form an integral body. There is a weighing sensor 5 below the lower tray 4, which can measure the gas weight in the gas cylinder group in real time and transmit it to the control system (not shown in the figure) and display it on the display. When the liquid xenon in the gas cylinder 3 is output outward, it is carried out through the lower pipeline 10. The upper refrigerant pipeline 7 and the lower refrigerant pipeline 9 are respectively connected to the upper heat exchanger 22 and the lower heat exchanger 25 in the gas cylinder group module, and a refrigerant at a specified temperature is introduced to make the gas cylinder 3 and the xenon gas inside work at a specified temperature. The thickness of the thermal insulation material 8 of the gas cylinder group is 100 mm, and it exists on all six surfaces of up, down, left, right, front, and back. The thermal conductivity of the foam thermal insulation material 8 is about 0.022 W / (m·k). The total area of the thermal insulation material 8 is about 53㎡. Calculated according to a temperature difference of 60℃ inside and outside, the heat leakage power is about 700 W. Or a combination of vacuum insulating glass and foam thermal insulation material is adopted. The heat transfer coefficient of the 12 mm thick vacuum insulating glass can reach 0.45 W / (㎡·K), which is converted into a thermal conductivity of W / (m·k), equivalent to 4 times the thickness of the adiabatic foam. If two layers of vacuum insulating glass are used with 76 mm of foam filled in the middle, the heat leakage power can be controlled to 400 W.

[0075] Figure 2 The figure shows a schematic diagram of the connection structure between the gas cylinder 3 and the lower tray 4. The shoulder of the gas cylinder 3 is a spherical surface, and the lower shoulder of the gas cylinder 3 is placed on the lower tray 4 through the lower heat exchanger 25. The detailed structure of the lower heat exchanger 25 is as Figure 3As shown, it is an annular structure with an outer diameter of 400 mm, an inner diameter of 200 mm, and a height of 100 mm. The lower bottom surface is a plane and is placed on the lower tray 4. The upper bottom surface is a spherical surface, and the spherical radius is equal to the spherical radius of the shoulder of the gas cylinder 3. The upper bottom surface of the lower heat exchanger 25 cooperates with the shoulder at the lower end of the gas cylinder 3, and a thermal conductive adhesive is applied between them. The thermal conductivity of the thermal conductive adhesive is not less than 1 W / (m·k), and there is a temperature sensor 21. The contact area between the heat exchanger 25 and the shoulder of the gas cylinder 3 is approximately 0.1 ㎡. When cooling, the rated temperature of the ethanol secondary refrigerant is 235 K. Calculated according to the thickness of the thermal conductive adhesive of 1 mm, the heat conduction capacity of the thermal conductive adhesive is still 300 W at a temperature difference of 3 K. Considering that the materials of the heat exchanger 22 and the gas cylinder 3 both have relatively high thermal conductivities, the heat exchange-related design is sufficient for the precooling requirement.

[0076] The connection structure between the gas cylinder 3 and the upper tray 2 is similar, and there is the same heat exchanger 22 for transition between them. There is also a thermal conductive adhesive and a temperature sensor between the upper heat exchanger 22 and the gas cylinder 3. The difference is that the orientation of the heat exchanger 22 is opposite to the up-and-down orientation of the heat exchanger 25 at the lower end of the gas cylinder 3.

[0077] Figure 3 It is a structural diagram of the upper heat exchanger 22, which has an inlet pipe orifice 22A and an outlet pipe orifice 22B with an inner diameter of 20 mm for the ethanol secondary refrigerant to enter and exit. The inlet pipe orifice 22A and the outlet pipe orifice 22B are symmetrical and can be used for both inlet and outlet. There is an annular secondary refrigerant channel 22C inside the heat exchanger 22 with a diameter of 30 mm, which can effectively enable the secondary refrigerant to exchange heat with the heat exchanger 22.

[0078] Before the gas cylinder group and the related system recover xenon from the detector or fill liquid xenon into the detector 100, it is necessary to precool the gas cylinder group and the internal gas.

[0079] The gas cylinder group designed in this embodiment has N = 12 gas cylinders 3, with a total filling of xenon of 1750 kg × 12 = 21000 kg, and the weight of the gas cylinders is 1370 kg × 12 = 16440 kg. Five gas cylinder groups can store xenon in the hundreds of tons, meeting the requirements of the long-term PandaX experiment. When precooling starts, the room temperature is calculated as 298 K. At this time, xenon is in a supercritical state, and the density of xenon gas is 1750 kg / m 3 , and the specific enthalpy of xenon gas is 55.3 kJ / kg. When cooled to 238 K, xenon is in a gas-liquid two-phase coexistence state, the density of liquid xenon is 2358 kg / m 3 , and the density of gaseous xenon is 154 kg / m 3 , from which it can be calculated that in a 1000 L gas cylinder, there is 724 L of liquid xenon, 1708 kg, and about 276 L of gaseous xenon, 42 kg, accounting for only 2.4%. It can be seen that most of the xenon has been liquefied, and it is reasonable to neglect gaseous xenon in thermodynamic calculations, and the aforementioned cooling capacity requirement is relatively accurate.

[0080] The specific enthalpy change from supercritical xenon at 298K to liquid xenon at 238K is 28.3 kJ / kg. The total refrigeration capacity required to cool all the xenon in the gas cylinder group to 238K is approximately 6×10 8 J. The gas cylinder material is 4130X, with a specific heat capacity of approximately 500 J / (kg·K). The total refrigeration capacity required to cool from 298K to 238K is 5×10 8 J. That is, each gas cylinder group requires 11×10 8 J of refrigeration capacity to cool down to 238K. After deducting the heat leakage, a refrigeration power of 1 kW can reach the target temperature in about 13 days. The installation of the detector has strong planning, and the refrigeration power required during the pre-cooling stage is not large. For the pre-cooling of the gas cylinder group before xenon recovery, there is only a small amount of xenon in the gas cylinder, and only the gas cylinder needs to be cooled. With the same refrigeration power, the pre-cooling time is shorter. At the same time, considering that the insulation layer has good heat insulation effect, the normal working temperature of the gas cylinder group can also be lower than room temperature, so the pre-cooling time required before filling and recovery is relatively short.

[0081] After the detector is installed, it takes a long time to evacuate. The currently operating PandaX-4T detector has a pressure vessel volume of about 3m 3 and requires about 6 tons of xenon, weighing about 1 ton. It takes about 7 days to evacuate before filling the liquid xenon; the next-generation PandaX-30T detector requires about 30 tons of xenon, with a pressure vessel volume of about 13m 3 and weighs about 5 tons. The evacuation time required is about 30 days; for the long-term PandaX detector, which may be in the hundreds of tons, the required pressure vessel volume is about 40m 3 . This evacuation time, which is the pre-cooling time of the xenon gas cylinder group, is very sufficient.

[0082] Figure 4 It is a flow chart for the rapid liquefaction and filling of xenon. The dashed box represents two or more gas cylinders 3 in the gas cylinder group. Each gas cylinder 3 has an upper electric valve 24 and a lower electric valve 23. There is a normal-temperature high-pressure xenon gas cylinder 62 outside the gas cylinder group, which is connected to the upper electric valve 24 through the first electric valve 61 and the first pressure reducing valve 60. After opening the first electric valve 61 and the upper electric valve 24, the high-pressure xenon gas in the high-pressure xenon gas cylinder 62 enters the first gas cylinder in the gas cylinder 3 through the first pressure reducing valve 60 and the upper electric valve 24 above the first gas cylinder. After a large amount of liquid xenon is quickly discharged from the bottom of the gas cylinder during the filling stage, in order to avoid excessive cooling caused by the vaporization of a large amount of liquid xenon beyond the working temperature range of the gas cylinder, the normal-temperature xenon gas in the normal-temperature high-pressure xenon gas cylinder 62 can be used to supplement the gas cylinder 3. The rated output pressure of the first pressure reducing valve 60 is 2 MPa, and it can also be adjusted up and down according to the actual situation.

[0083] After gaseous xenon or liquid xenon is output through the electric valve 23 under the gas cylinder 3, it successively passes through the second electric valve 41, the intermediate heat exchanger 42, the first gear pump 43, the first buffer 44, the terminal heat exchanger 46, the second gear pump 47, the second buffer 48, the third electric valve 50, and the third gear pump 51, and finally enters the PandaX detector 100.

[0084] The first buffer 44 is provided with a first xenon gas pipeline 59 connected to the PandaX detector 100. There are a fifth electric valve 58 and a third pressure reducing valve 57 on the first xenon gas pipeline 59. The second buffer is provided with a second xenon gas pipeline 54 connected to the PandaX detector 100. There are a fourth electric valve 56 and a second pressure reducing valve 55 on the second xenon gas pipeline 54. The rated output pressures of the third pressure reducing valve 57 and the second pressure reducing valve 55 are 0.25 Mpa, and the rated working pressure of the detector 100 is 0.2 MPa. The first buffer 44 is provided with a second pressure sensor 45 for measuring pressure, the second buffer 48 is provided with a third pressure sensor 49 for measuring pressure, and the PandaX detector 100 is provided with a fourth pressure sensor 53 for measuring pressure. The PandaX detector 100 is also designed with a refrigeration system 52 to provide the required refrigeration capacity for the normal operation of the detector 100, and can also provide refrigeration capacity during the liquid xenon / gaseous xenon filling stage.

[0085] The working process of the large-scale storage, rapid liquefaction and recovery device for high-purity xenon gas in this embodiment is as follows:

[0086] A: High-purity xenon filling process

[0087] 1) After the PandaX detector 100 completes the vacuum pumping work, xenon gas can be filled into the PandaX detector 100 and pre-cooled to a target temperature of 178 K. The convection caused by the temperature gradient of the xenon gas inside the detector 100 during the pre-cooling process helps to evenly cool the detector and reduce the risk brought to the detector by excessive thermal stress during the cooling process. First, turn on the first refrigerator and the second refrigerator. After reaching the rated working temperature, the first refrigerator and the second refrigerator respectively cool the intermediate heat exchanger 42 and the terminal heat exchanger 46. Taking the PandaX-30T detector as an example, the volume of the pressure vessel is about 13 m 3 , weighing about 5 tons. Using a refrigerator with a refrigeration power of 2 kw, it can be cooled to 178 K in 48 h;

[0088] 2) After confirming that the actual temperature of the gas cylinder group is within the rated range of 238K ± 3K, open the electric valve 23 below the gas cylinder 3, and use the first pressure sensor 63 to confirm again that the pressure is below 2MPa, then start the first gear pump 43 and rotate it in the reverse direction. The initial speed is 1000r / min (the maximum speed is 3000r / min. At this time, the function of the first gear pump 43 is dynamic flow resistance, the input pressure is higher than the output pressure, and adjusting the speed of the first gear pump 43 can obtain different flow rates. Rotating in the reverse direction can offset the effect of internal leakage of the gear pump). Open the second electric valve 41, and the high-pressure liquid xenon enters the intermediate heat exchanger 42. The rated outlet temperature of the intermediate heat exchanger 42 is -60°C. The liquid xenon at -60°C slowly enters the first buffer container 44. Considering that the initial temperature of the relevant pipelines and the first buffer container 44 is relatively high, the liquid xenon first cools the relevant pipelines and the first buffer container 44 and vaporizes. At the same time, the air pressure in the first buffer container 44 gradually rises, and accurate pressure data can be obtained through the second pressure sensor 45. If it exceeds 1MPa, then close the second electric valve 41. While starting the first gear pump 43, also start the second gear pump 47 (the initial reverse speed is 1000r / min) and the fourth electric valve 56. The second buffer 48 is cooled and pressurized accordingly, and the xenon gas also enters the detector 100 through the first xenon gas pipeline 54, the fourth electric valve 56, and the second pressure reducing valve 55. The detector is slowly pressurized, and the internal air pressure of the detector 100 can be obtained through the fourth pressure sensor 53. As the filling process progresses, all relevant devices and pipelines are gradually cooled to the rated working temperature. Taking the PandaX-30T detector as an example, the internal volume is about 13m 3 , and the density of xenon gas at normal temperature of 0.2MPa is about 11kg / m 3, it takes about 143 kg of xenon to fill the detector 100 with xenon to 0.2 MPa. If the liquid xenon equivalent flow rate of the first gear pump 43 and the second gear pump 47 is 0.1 L / min, that is, 0.24 kg / min, it takes about 600 min to fill 143 kg of xenon. When filling to the rated pressure of 0.2 MPa, the lower electric valve 23, the 4th electric valve 41, the 6th electric valve 56, the first gear pump 43, and the second gear pump 47 are closed in sequence. Since there is internal leakage when the gear pump stops rotating, this also ensures that after closing the above valves and gear pumps, the pressure inside the pipeline and the first buffer container 44 and the second buffer container 46 tend to balance. During this filling process, the detector 100 continues to be precooled, and the precooling power is 2 kw. As the precooling progresses, the detector 100 and the internal xenon gradually cool down, and the pressure decreases accordingly, which requires timely replenishment of xenon. If the xenon pressure inside the first buffer container 44 and the second buffer container 48 is relatively high, opening the 4th electric valve 56 or the 5th electric valve 58 can replenish it. If the pressure is relatively low, it is necessary to open the lower electric valve 23 and the 2nd electric valve 41 to replenish the first buffer container 44 to 1 MPa according to the aforementioned process. It is estimated that the total precooling process takes 48 h;

[0089] 3) After the precooling work is completed, liquid xenon begins to accumulate at the bottom inside the detector 100. The cooling capacity provided by the refrigeration system 52 is all used for the liquefaction of xenon. The required injection rate of gaseous xenon is 1.2 kg / min to maintain the internal air pressure constant;

[0090] 4) After precooling is completed, high-speed filling of liquid xenon can begin. Open the lower electric valve 23, the 2nd electric valve 41, the 4th electric valve 56, and the 3rd electric valve 50 in sequence, and ensure that the input coolant temperature and flow rate of the intermediate heat exchanger 42 and the end heat exchanger 46 are normal. Adjust the rotation speed of the first gear pump 43 so that the pressure of the first buffer container 44 is within the range of 0.8 - 1.0 MPa, adjust the rotation speed of the second gear pump 47 so that the pressure of the second buffer container 48 is within the range of 0.15 - 0.25 MPa, and start the third gear pump 51 to inject liquid xenon into the detector 100. Because the refrigeration system 52 still provides refrigeration power, when the air pressure inside the detector 100 is relatively low, the 5th electric valve 58 can be opened, and after being decompressed by the third pressure reducing valve 57, gaseous xenon is injected into the detector 100 to maximize the utilization of the refrigeration power. During this process, xenon from the normal temperature high-pressure xenon gas cylinder 62 needs to be used to replenish the gas cylinder 3.

[0091] 5) After the liquid xenon filling is completed, the gaseous xenon in the gas cylinder group still has a pressure of 2 MPa, and the density is about 154 kg / m 3, and its total amount is also relatively large. At this time, the xenon entering the intermediate heat exchanger 42 is in gaseous state. There is a gas-liquid phase transition in this process, and the liquefaction process requires a large amount of refrigeration. At this time, the filling speed is reduced to about 10% of the steady-state condition, and the process is still carried out in the manner of step 4) until the gas pressure in the gas cylinder 3 drops to 0.3MPa or is consistent with the pressure of the detector 100. In fact, the transition from step 4) to this step is natural, except that the filling flow rate changes;

[0092] 6) The remaining xenon gas in the gas cylinder 3 can be collected by soaking it in liquid nitrogen in a stainless steel bottle, then warmed up, and slowly added to the detector 100 after being vaporized.

[0093] At this point, the filling of high-purity xenon is completed and the detector can be put into normal operation.

[0094] B. Normal recovery process of high purity xenon

[0095] 7) Before recycling, each gas cylinder 3 in the gas cylinder group is cooled to 238K by using the upper heat exchanger 22, and then the refrigeration system 52 connected to the detector 100 is turned off, and i=1;

[0096] 8) Open the upper electric valve 24 and the third electric valve 50 of the i-th gas cylinder 3, open the first electric heater 72 and the second electric heater 74, slowly open the third gear pump 51, extract liquid xenon from the detector 100, heat it in turn through the second electric heater 74 and the first electric heater 72, and then pump it into the i-th gas cylinder 3. The second thermometer 73 measures the liquid xenon heated by the second electric heater 74, and the target temperature is 208±3K. The first thermometer 71 measures the liquid xenon heated by the first electric heater 72, and the target temperature is 238±1K. The speed of the third gear pump 51 and the heating power of the second electric heater 72 and the first electric heater 74 are all controlled by PLC (not shown in the schematic diagram). After the system becomes stable, gradually increase the speed of the third gear pump 51, that is, increase the flow rate of liquid xenon. During the recovery process, continuously use the fifth pressure sensor 75 to detect the system pressure.

[0097] 9) The weight of the liquid xenon injected into the i-th gas cylinder 3 is obtained according to the weighing sensor 5 below the gas cylinder group. When it is close to 1750kg, the upper electric valve 24 of the i-th gas cylinder 3 is immediately closed.

[0098] 10) When i <N时,令i=i+1,返回步骤8),当i大于N时,进入下一步;

[0099] 11) After the liquid xenon is recovered, the stainless steel PandaX detector 100 and other gas xenon in the pipelines are finally used.

[0100] 12) After the high-purity xenon is recovered, the gas cylinder group is transferred to normal storage status.

[0101] Emergency recovery process of high-purity xenon C:

[0102] As analyzed above, if the gas cylinder has not been pre-cooled to 238K during the experiment, rapid recovery of 178K liquid xenon is still possible. The recovery timing sequence is for reference Figure 6 .

[0103] First, open the upper electric valve 24, lower electric valve 23, second electric valve 41, and third electric valve 50. Start the third gear pump 51 to transport 178K liquid xenon to the gas cylinder 3. In the initial stage, the pipelines 86, fourth heat exchanger 84, third electric heater 81, pipeline 10, etc. that the liquid xenon passes through in sequence have relatively high temperatures. The liquid xenon heats up until it vaporizes, and the air pressure in the gas cylinder 3 also increases accordingly. As the recovery progresses, the temperature of the xenon entering the gas cylinder 3 gradually decreases. To prevent damage to the gas cylinder due to low temperature, it is necessary to ensure that the temperature of the xenon leaving the electric heater is not lower than 238K. The temperature of the xenon is measured by the third temperature sensor 82 and fed back to the third electric heater 81. As the recovery progresses, the pressure inside the gas cylinder gradually increases. When it reaches 1.8MPa, the corresponding boiling point is approximately 238K. After the low-temperature liquid xenon enters the cold side of the fourth heat exchanger, it exchanges heat with the gaseous xenon from the top of the gas cylinder 3. The gaseous xenon is cooled and condensed, and then is pressurized by the fourth gear pump 85 and enters the pipeline 86, where it is mixed with the low-temperature liquid xenon from the detector 100 and enters the cold side of the plate heat exchanger. After heat exchange and temperature rise, it enters the third electric heater 81, lower pipeline 10, and third electric valve 23 in sequence and then enters the gas cylinder 3. Since the temperature of the gas cylinder 3 is higher than the temperature of the liquid xenon, part of the liquid xenon vaporizes while the gas cylinder 3 is cooled. The gaseous xenon enters the third heat exchanger 83 and fourth heat exchanger 84 from the second electric valve 24 above the gas cylinder 3 through the upper pipeline 6 for cooling and liquefaction. The boiling point of xenon is very significantly affected by air pressure. The boiling point corresponding to 2MPa is 243K, and the boiling point corresponding to 2.3MPa is 248K. The power density of condensation heat exchange is much higher than that of heat conduction. Therefore, the fourth heat exchanger 84 and fourth gear pump 85 can effectively exchange heat and mix the 178K liquid xenon from the detector with the gaseous xenon from the top of the gas cylinder 3, ensuring the effective utilization of cold energy. If the pressure inside the gas cylinder exceeds 2.3MPa, the first refrigerator is started to supplement refrigeration for the xenon gas through the third heat exchanger 83. If the temperature of the liquid xenon measured by the third temperature sensor 82 is lower than 238K, the third electric heater 81 is started to supplement heat to avoid the micro or instantaneous temperature and pressure exceeding the working range. Since the liquid xenon is injected into the gas cylinder 3 from the bottom, and compared with the recovery speed of xenon, the heat conduction of the steel gas cylinder itself is slow, and only a small local area of the gas cylinder body needs to be cooled. Therefore, the heat exchange process during the recovery process is relatively mild, and the required supplementary cold energy and heating energy are also small.

[0104] However, to improve the reliability of the recovery process, it is still necessary to ensure that the pre-cooling temperature of the gas cylinder 3 is close to 238K as much as possible.

[0105] Example 2

[0106] The critical temperature of ethylene is 9.6 °C, the critical pressure is 5.07 MPa, the boiling point is -103.7 °C, and the melting point is -169.4 °C. Its thermodynamic properties are similar to those of xenon. In cases where a large amount of high-purity liquid ethylene is required, the device of the present invention can also be used for storage, liquefaction, recovery and other operations. The filling coefficient of ethylene is 300 kg / m 3 When the temperature is 333 K, the corresponding pressure is 16 MPa, which meets the safety requirements. As the temperature decreases, the gas pressure drops rapidly. At the standard room temperature of 298 K, the gas pressure has dropped to 8.5 MPa. The saturated vapor pressure corresponding to 238 K is lower than 1.7 MPa. The specific enthalpy of ethylene is 383 kJ / kg at 298 K, and the specific enthalpy of liquid ethylene at the gas-liquid equilibrium at 238 K is 179 kJ / kg, showing an obvious decrease. Precooling can also effectively reduce the refrigeration power or time required for conventional liquefaction.

[0107] In the present invention, the thermodynamic properties of ethylene are similar to those of xenon. Considering the price difference between the two, when testing the actual device of the present invention, ethylene can be used to replace xenon for testing in the initial stage.

[0108] Example 3

[0109] For other gases, such as high-purity ethane, the principle is similar. In cases where a large amount of high-purity liquid ethane is required, the device of the present invention can also be used for implementation and management.

[0110] The present invention has been described by the above related embodiments. However, the above embodiments are only examples for implementing the present invention, and the above embodiments do not limit the scope of the present invention. On the contrary, any changes and modifications made without departing from the spirit and scope of the present invention fall within the scope of the patent protection of the present invention.

Claims

1. A large-scale storage, rapid liquefaction and recovery device for high-purity gas, characterized in that, It includes a storage gas cylinder group, a liquid xenon recovery pipeline, and a liquid xenon emergency recovery pipeline; The storage gas cylinder group mentioned above includes a gas cylinder group frame (1) and a gas cylinder group. The gas cylinder group frame (1) is a heat-insulated cavity formed by a frame and a heat-insulating layer (8) wrapping the frame. The gas cylinder group is placed in the heat-insulated cavity. The gas cylinder group includes an upper tray (2), a lower tray (4), and a plurality of gas cylinders (3) placed between the upper tray (2) and the lower tray (4). Shoulder parts at the upper and lower ends of each gas cylinder (3) are respectively provided with an upper heat exchanger (22) and a lower heat exchanger (25). Upper and lower electric valves (24) and (23) are respectively installed at the upper and lower bottle mouths of each gas cylinder (3). A weighing sensor (5) is provided below the lower tray (4). On the upper tray (2), there are an upper pipeline (6) connected to the upper electric valve (24) of each gas cylinder (3), and an upper secondary coolant pipeline (7) connected to the upper heat exchanger (22) of each gas cylinder (3). On the lower tray (4), there are a lower pipeline (10) connected to the lower electric valve (23) of each gas cylinder (3), and a lower secondary coolant pipeline (9) connected to the lower heat exchanger (25) of each gas cylinder (3); During the filling operation, the upper pipeline (6) is successively connected to an external high-pressure gas cylinder (62) via a first pressure reducing valve (60) and a first electric valve (61). The side of the gas cylinder (3) is the low-pressure side of the first pressure reducing valve (60); During the filling operation, the lower pipeline (10) is successively connected to port 1 of a PandaX detector (100) via a second electric valve (41), an intermediate heat exchanger (42), a first gear pump (43), a first buffer (44), a terminal heat exchanger (46), a second gear pump (47), a second buffer (48), a third electric valve (50), and a third gear pump (51). A first pressure sensor (63) is provided on the lower pipeline (10) before the second electric valve (41). A second pressure sensor (45) is provided on the first buffer (44). A third pressure sensor (49) is provided on the second buffer (48). The second buffer (48) is provided with a second xenon pipeline (54). This second xenon pipeline (54) is successively connected to port 2 of the PandaX detector (100) via a fourth electric valve (56) and a second pressure reducing valve (55). The first buffer (44) is provided with a first xenon pipeline (59). This first xenon pipeline (59) is successively connected to port 3 of the PandaX detector (100) via a fifth electric valve (58) and a third pressure reducing valve (57). The liquid xenon recovery pipeline includes a first thermometer (71), a first electric heater (72), a second thermometer (73), and a second electric heater (74) connected in sequence. Two ends of this liquid xenon recovery pipeline are respectively connected to the upper pipeline (6) and the third port of the third electric valve (50); The described liquid xenon emergency recovery pipeline includes a third electric heater (81), a third temperature sensor (82), a third heat exchanger (83), a fourth heat exchanger (84), a fourth gear pump (85) and a pipeline (86). On the pipeline (86) between the third electric valve (50) and the lower pipeline (10), the third electric valve (50) is connected to the 84-1 port of the fourth heat exchanger (84). The 84-2 port of this fourth heat exchanger (84) is connected to the inlet end of the third electric heater (81). The outlet end of this third electric heater (81) is connected to one end of the second electric valve (41). The fourth gear pump (85) is connected between the 84-4 port and the 84-1 port of the fourth heat exchanger (84), and the driving direction is from the 84-4 port to the 84-1 port. A third temperature sensor (82) is provided on the pipeline between the third electric heater (81) and the second electric valve (41). The 83-2 end of the third heat exchanger (83) is respectively connected to the upper pipeline (6). The 83-4 of the third heat exchanger (83) is connected to the 84-3 port of the fourth heat exchanger (84). The described intermediate heat exchanger (42) and end heat exchanger (46) are also respectively connected to the first chiller and the second chiller during the high-purity gas filling stage. The 83-1 and 83-2 ends of the third heat exchanger (83) are connected to the first chiller during the emergency recovery stage.

2. The large-scale storage, rapid liquefaction and recovery device for high-purity gas according to claim 1, characterized in that, The described PandaX detector (100) is also provided with a refrigeration system (52) and a fourth pressure sensor (53).

3. The large-scale storage, rapid liquefaction and recovery device for high-purity gas according to claim 1, characterized in that, The design pressure of the described gas cylinder (3) is not less than 10 MPa.

4. The large-scale storage, rapid liquefaction and recovery device for high-purity gas according to claim 1, characterized in that, The described gas cylinder (3) and valve can work for a long time at a temperature of -30°C and below. The gaseous xenon or liquid xenon output by the gas cylinder (3) has a temperature between -40°C and -30°C.

5. The large-scale storage, rapid liquefaction and recovery device for high-purity gas according to claim 1, characterized in that, The described thermal insulation layer (8) is composed of a low-thermal-conductivity material or is made of vacuum insulation. The thermal conductivity of the low-thermal-conductivity material is not greater than 0.1 W / (m·K), the thickness is not less than 50 mm, the total area is not less than the surface area of a single gas cylinder, and the effective thermal conductivity is not greater than 20 W / K.

6. The large-scale storage, rapid liquefaction and recovery device for high-purity gas according to claim 1, characterized in that, The temperature control structure of the described gas cylinder (3) is made of copper, aluminum or a material with a thermal conductivity not less than 100 W / (m·K), has an internal heat exchange fluid passage, and has at least 2 inlet pipes (22A) and outlet pipes (22B) for the heat exchange fluid. The temperature control structure and the cylinder body of the gas cylinder (3) are closely matched through a thermal conductive adhesive. The matching area is not less than 50 square centimeters, and the average normal stress of the matching surface is not less than 1000 Pa.

7. The large-scale storage, rapid liquefaction and recovery device for high-purity gas according to claim 1, characterized in that, The design pressures of the described intermediate heat exchanger (42), end heat exchanger (46), third heat exchanger (83), fourth heat exchanger (84), first gear pump (43), second gear pump (47), third gear pump (51), fourth gear pump (85), first buffer (44), second buffer (48), first electric valve (61), second electric valve (41), third electric valve (50), fourth electric valve (56), and fifth electric valve (58) are not less than 2 MPa, and they have a heat preservation structure.

8. The large-scale storage, rapid liquefaction and recovery device for high-purity gas according to claim 1, characterized in that, The described first gear pump (43), second gear pump (47), third gear pump (51), and fourth gear pump (85) are gear pumps driven by magnetic couplings without dynamic seals.

9. The large-scale storage, rapid liquefaction and recovery device for high-purity gas according to claim 8, characterized in that, The described first gear pump (43), second gear pump (47), third gear pump (51), and fourth gear pump (85) are also used for the cyclic purification of gas / liquid.

10. The large-scale storage, rapid liquefaction and recovery device for high-purity gas according to claim 1, characterized in that, The described first refrigerator and second refrigerator are self - cascading refrigerators, which have two sets of evaporators. One set is used to cool the secondary refrigerant, and the secondary refrigerant is anhydrous ethanol; the other set is used to cool the high - purity gas.

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