Isotope gas cryoadsorption separation system and method

Abstract

The application provides a kind of isotopic gas cryogenic adsorption separation system and method, system includes isotopic gas control system, cryogenic control system, adsorption column and gas detection system;Cryogenic control system includes refrigerator, and the cold head of refrigerator is wound with several turns of gas precooling tube, and the outlet of gas mixing chamber in isotopic gas control system is connected with the lower end of precooling tube, and the upper end of precooling tube is connected with the gas inlet of adsorption column, and the adsorption column is placed on the cold head, and the cold head is connected with temperature controller, and the cold head and adsorption column are placed in vacuum cover, and gas detection system includes mass spectrometer;Mass spectrometer is connected with the gas outlet of adsorption column.In addition, it also includes temperature storage system for temperature prestorage, realizes the rapid temperature rise / fall of adsorption column.The application solves the problem that the temperature of isotopic dynamic cryogenic adsorption separation in the prior art is uncontrollable, and further solves the problem that the slow temperature rise / fall rate leads to low equipment operation efficiency, which has great significance and value.

Description

Technical Field

[0001] The present invention belongs to the technical field of isotope separation, and relates to a low-temperature adsorption separation system and method for isotope gas. Background Art

[0002] In recent years, stable isotope gases have been increasingly used in scientific research and production technology. Therefore, the preparation and enrichment technology of stable isotope gases has also been vigorously developed. Since the atomic number of isotope gases is the same and the number of electrons outside the nucleus is the same, the difference in their physical and chemical properties is very small, and the natural abundance is low. The enrichment and separation and purification of isotopes are technically difficult and energy-intensive. Common isotope gases include: hydrogen isotopes (H2 / D2 / T2), oxygen isotopes ( 16 O2 / 18 O2), methane isotopes ( 12 CH4 / 13 CH4, 12 CH4 / 12 CD4) etc.

[0003] The main industrial isotope gas separation methods include cryogenic distillation, thermal diffusion, chemical exchange, and quantum sieving. In recent years, quantum sieving has become a highly promising isotope separation process due to its high separation factor and low energy consumption compared to other methods. Research on isotope quantum sieving has primarily focused on the development of adsorbents. Currently, evaluation equipment for the isotope separation performance of novel porous materials is mostly performed using single-component gases under static conditions, such as adsorption isotherms, in situ infrared spectroscopy, and low-temperature thermal desorption spectroscopy. These evaluation equipment cannot directly demonstrate the dynamic adsorption separation performance of an adsorbent in an actual mixed isotope gas. The actual separation performance of an adsorbent is typically verified through column penetration experiments of the mixed gas under dynamic conditions. However, the most studied dynamic penetration experiments for low-temperature isotope adsorption separation are primarily conducted under liquid nitrogen conditions (77K), making testing at other temperatures impossible. Therefore, the adsorption separation performance of an adsorbent under dynamic mixed isotope gas conditions at other temperatures cannot be measured. However, for isotope separation using porous adsorbents, the lower the separation temperature, the better the isotope adsorption separation performance. In addition, conventional low-temperature temperature control devices have slow cooling and heating rates, resulting in long experimental operation time and poor efficiency. Summary of the Invention

[0004] The present invention aims to address the problems and shortcomings of the aforementioned prior art by providing a low-temperature adsorption separation system and method for isotope gas separation. This system and method address the uncontrollable temperature problem of isotope dynamic low-temperature adsorption separation in the prior art, and further addresses the low operating efficiency caused by slow temperature rise / fall rates, thus being of great significance. Furthermore, compared with existing invention patents, the low-temperature adsorption separation system and method of isotope gas of the present invention boasts high isotope separation efficiency, a wide and controllable adsorption column test temperature range, a fast temperature rise / fall rate for the adsorption column, a simple structure, reliable operation, and convenient operation.

[0005] To achieve the above object, the technical solution adopted by the present invention is: an isotope gas low-temperature adsorption separation system, including an isotope gas control system, a low-temperature control system, an adsorption column and a gas detection system;

[0006] The isotope gas control system includes isotope gas and a gas mixing chamber, and the isotope gas is connected to the inlet of the gas mixing chamber respectively;

[0007] The low-temperature control system includes a refrigerator, a temperature controller, and a vacuum cover. A plurality of gas pre-cooling tubes are wound around the cold head of the refrigerator. The outlet of the gas mixing chamber is connected to the lower end of the pre-cooling tube, and the upper end of the pre-cooling tube is connected to the air inlet of the adsorption column. The adsorption column is placed on the cold head, and the temperature controller is connected to the cold head. The cold head and the adsorption column are placed in a vacuum cover to prevent energy leakage. The adsorption column and the cold head are each provided with a temperature sensor, and the low-temperature temperature can be controlled within a range of 4.2-300K.

[0008] The gas detection system includes a mass spectrometer; the mass spectrometer is connected to the gas outlet of the adsorption column.

[0009] The cooling rate can be controlled in the range of 0.5-5K / min.

[0010] The isotope gas control system also includes a purge gas, and the outlet of the gas mixing chamber is connected to the purge gas and then to the lower end of the pre-cooling tube; the gas outlet of the adsorption column is connected to the gas storage tank, the mass spectrometer and the gas pipeline vacuum pump respectively through a three-way ball valve. The gas pipeline vacuum pump is used to adjust the adsorption pressure of the gas in the adsorption column, and the pressure adjustment range is 0.0001-100kPa.

[0011] The controllable range of the low temperature is 4.2-76K.

[0012] For low-temperature control, the temperature controller is connected to the cold head. The temperature controller maintains the target temperature by turning on the refrigerator and controlling the voltage output. The temperature controller can also maintain the target temperature by controlling the heating voltage output, as well as program the temperature increase to achieve high-temperature control. The high-temperature controllable range is 300-800K, and the heating rate can be controlled within a range of 0.5-10K / min.

[0013] The system also includes a temperature storage system for temperature pre-storage, which includes a temperature storage metal block and a vacuum cover. The temperature storage metal block is connected to the cold head through a temperature conducting tube. The temperature conducting tube is provided with a temperature conducting valve. The temperature conducting valve is controlled to open and close the cold or heat transport between the temperature storage metal block and the cold head. The temperature storage metal block is respectively connected to a refrigerator, a temperature controller and a temperature sensor for heating / cooling and controlling the temperature. The temperature storage metal block and the temperature conducting tube are placed in the vacuum cover to prevent energy leakage.

[0014] The temperature of the heat storage metal block is controlled by using a temperature control device to pre-store cold or hot energy in the heat storage metal block or to recover energy from the cold head for energy storage. The heat storage metal block in the heat storage system can store temperatures ranging from 10-500K. The energy of the heat storage metal block is quickly transferred to the cold head by controlling the opening and closing of the temperature transfer valve. After the energy exchange with the cold head is completed, the temperature transfer valve is closed.

[0015] The heat storage metal block is wrapped with glass fiber to prevent leakage of cold energy.

[0016] The isotope gases in the isotope gas control system are connected to the inlet of the gas mixing chamber through a pressure reducing valve and a mass flow meter respectively, and the purge gas is connected after the stop valve of the gas mixing chamber.

[0017] The adsorption column is a packed fixed bed, made of pure copper to ensure low-temperature transmission and facilitate screw fixation. Furthermore, the adsorption column structure is a disc-shaped adsorption column, with wing-like structures on both sides of the adsorption column. The bottom of the disc-shaped adsorption column is a flat plate structure to increase its contact surface with the cold head, and the wing-like structure is fixed to the cold head by screws. Furthermore, a gasket is provided at the bottom of the adsorption column. The gasket is an ultra-thin indium sheet with excellent ductility and thermal / cold conductivity, which reduces poor contact between the adsorption column and the cold head due to unevenness.

[0018] The size of the adsorption column is customized according to the size of the cold head. The length of the adsorption column is 5-1000cm and the radius is 0.6-200cm.

[0019] The cold head is cylindrical with a radius of 8-1100 cm.

[0020] The isotope gases in the mixing chamber are: hydrogen isotopes (H2 / D2 / T2), oxygen isotopes ( 16 O2 / 18 O2), methane isotopes ( 12 CH4 / 13 CH4, 12 CH4 / 12 CD4), nitrogen isotopes ( 14 N2 / 15 N2, 14 NH3 / 15 NH3), ammonia isotopes ( 14 NH3 / 15 NH3, 14 NH3 / 14 ND3), carbon dioxide isotopes ( 12 CO2 / 13 CO2, 12 C 16 O2 / 12 C 18 O2) or noble gas isotopes ( 3 He / 4 He, 20 Ne / 21 Ne / 22 Ne, 36 Ar / 38 Ar / 40 Ar).

[0021] An electromagnetic valve is provided on a pipeline which is connected to the lower end of the precooling pipe after the outlet of the gas mixing chamber is connected to the purge gas.

[0022] The temperature rise / fall rate of the temperature storage block can be controlled in the range of 0.5-5K / min.

[0023] The adsorption column and the cold head are each provided with two temperature sensors, namely a low-temperature sensor and a high-temperature sensor. The low-temperature sensor detects temperatures of 300K and below, and the high-temperature sensor detects temperatures above 300K.

[0024] The heat storage metal block is composed of an AgCu solid solution, an AgZr solid solution, an AgCe solid solution, an AgLa solid solution, a CuZr solid solution, a CuCe solid solution, or a CuLa solid solution. The heat storage metal block is a rectangular parallelepiped, with dimensions adjusted to the size of the cold head. The length is adjustable between 8 and 1100 cm, and the ratio of length to width or height is in the range of 0.1 to 1:0.05 to 0.5.

[0025] The adsorbent is one or more of metal oxides, non-metal oxides, inorganic salts, porous carbon, zeolite molecular sieves, metal organic frameworks (MOFs), covalent organic frameworks (COFs), hydrogen bond organic frameworks (HOFs) and porous polymers (POPs).

[0026] Before entering the adsorbent, the gas is pre-cooled by the pre-cooling tube wrapped around the cold head.

[0027] The air outlet of the adsorption column is provided with a vacuum gauge at the rear end of the adsorption column; the vacuum gauge at the rear end of the adsorption column and the pressure vacuum gauge in the vacuum cover are used to detect the vacuum degree of the adsorption column, the pipeline and the vacuum chamber.

[0028] The present invention also provides a separation method of the separation system, including an isotope low-temperature dynamic column breakthrough test, comprising the following steps:

[0029] S1 loads fresh adsorbent into the adsorption column, then fixes the adsorption column filled with adsorbent to the cold head and connects it to the pipeline. S2 purges or vacuums the adsorbent to remove impurities in the adsorbent.

[0030] S3: Install the vacuum cover, reduce the vacuum degree in the vacuum cover cavity to below 1Pa, and then continue to evacuate for more than 20 minutes;

[0031] S4 turns on the refrigerator and temperature controller connected to the cold head, sets the target temperature and starts cooling. During the cooling process, the purge gas or vacuum is kept running; when the target temperature is reached, the purge or vacuum is stopped.

[0032] S5 first introduces pure component isotope gases into the gas mixing chamber for mixing, and then passes them into the adsorption column that has been cooled to the target temperature to achieve adsorption and separation of the isotope gases. The isotope gas concentration at the outlet of the adsorption column is detected by mass spectrometry to determine whether the adsorbent has the dynamic separation performance of the isotope gases.

[0033] To replace the adsorbent, shut down the entire cryogenic system and allow the cryogenic system and adsorption column to reach room temperature. Then, open the vacuum hood inlet valve to raise the pressure inside the vacuum hood to atmospheric pressure. At this point, you can open the vacuum hood, remove the adsorption column, and replace the adsorbent.

[0034] It also includes rapid cooling before cooling, turning on the compressor and temperature controller connected to the metal temperature storage block to pre-cool the metal temperature storage block, the pre-cooling temperature is calculated based on the actual usage temperature of the adsorption column, so that the temperature is pre-stored, and the temperature conduction valve is opened to connect the temperature storage metal block with stored cold energy to the cold head through the temperature conduction pipe, and the cold energy is quickly transferred to the cold head, thereby achieving rapid cooling of the adsorption column on the cold head. When the temperature sensor values ​​of the cold head and the temperature storage metal block are consistent, the temperature conduction valve is closed, and the rapid cooling process is ended at this time, and then cooling is performed.

[0035] It also includes opening the temperature conducting valve after the isotope low-temperature dynamic column breakthrough test is completed to transfer the cold energy of the cold head to the metal temperature storage block through the temperature conducting tube for cold energy recovery, and conducting subsequent isotope low-temperature dynamic column breakthrough tests.

[0036] Also includes low temperature program thermal desorption test

[0037] After the breakthrough test of the isotope low-temperature dynamic column is completed, S1 opens the purge gas to enter the adsorption column to purge the adsorbent, and the concentration of the desorbed isotope is monitored online by mass spectrometry;

[0038] S2 When the adsorbent surface and the weakly interacting isotopes are purged clean, the adsorption column is programmed to heat up. During the heating process, the purge gas continuously purges the adsorbent, and the mass spectrometer monitors the isotope gas desorbed by the temperature increase online to obtain a low-temperature programmed temperature-desorption curve of the isotope gas in the adsorbent, which is used to determine the interaction force and adsorption site between the adsorbent and the isotope gas.

[0039] The method also includes adsorbent regeneration, which includes regenerating the adsorbent by purging, high temperature, vacuum, or high temperature vacuum after the isotope low temperature dynamic column breakthrough test is completed. After regeneration, the isotope low temperature dynamic column breakthrough test is repeated to perform an adsorption column cycle experiment.

[0040] During high-temperature or high-temperature vacuum regeneration, it also includes rapid heating before heating: turning on the temperature controller connected to the metal temperature storage block to quickly pre-heat the metal temperature storage block. The pre-heating temperature is calculated based on the actual operating temperature of the adsorption column to pre-store the temperature. Open the temperature conduction valve to connect the temperature storage metal block with heat storage to the cold head through a temperature conduction tube, and quickly transfer the heat to the cold head, thereby achieving rapid heating of the adsorption column on the cold head. When the temperature sensor values ​​of the cold head and the temperature storage metal block are consistent, close the temperature conduction valve. At this time, the rapid heating process ends and then heating is carried out again; or after the breakthrough test of the isotope low-temperature dynamic column is completed, open the temperature conduction valve before heating to transfer the cold energy of the cold head to the metal temperature storage block through the temperature conduction tube. At the same time, the temperature of the adsorption column has risen, which is equivalent to rapidly heating the adsorption column and then heating it.

[0041] Compared with the prior art, the technical solution of the present invention has the following advantages and beneficial effects:

[0042] This device can realize the actual mixed isotope column penetration performance of the adsorbent under dynamic conditions and can intuitively evaluate the actual isotope separation performance of the adsorbent.

[0043] Compared to existing dynamic isotope penetration devices that rely on liquid nitrogen for temperature control, this device can achieve stable control of the adsorption column in various low-temperature environments. Due to its enhanced low-temperature controllability, this device not only enables dynamic penetration separation of multiple isotopic gases, but also comprehensively tests the adsorbent's dynamic separation performance for mixed isotope gases at different low temperatures.

[0044] This system is equipped with an energy storage module. Through energy recovery and pre-cooling, a large amount of cold energy is stored in the metal block. This cold energy is then quickly transferred to the cold head through a thermal pipe, enabling rapid control of the target operating temperature of the adsorption column during the isotope separation process. Alternatively, a large amount of heat is stored in the metal block through pre-heating, and this heat is then quickly transferred to the cold head through a thermal pipe, enabling rapid control of the target operating temperature of the adsorption column during the regeneration process.

[0045] The system and its device are equipped with four adsorbent regeneration methods: purge, high temperature, vacuum, or high temperature vacuum. Different regeneration methods can be selected based on the strength of the adsorbent-adsorbate interaction and the required target gas composition. A mass spectrometer detection system ensures accurate isotopic gas detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The device for low-temperature dynamic penetration of isotope adsorption separation in the present invention comprises: a pressure reducing valve 1, a gas dryer 2, a gas mass flowmeter 3, an air inlet valve 4, a gas mixing chamber 5, an exhaust valve 6, a stop valve 7, a solenoid valve 8, a vacuum cover vacuum pump valve 9, a vacuum cover vacuum pump 10, a vacuum cover air inlet valve 11, a vacuum cover 12, a pressure gauge 13 in the vacuum cover, a temperature sensor 14, a pre-cooling tube 15, an adsorption column 16, a cold head 17, a refrigerator 18, a temperature controller 19, a vacuum gauge 20 at the rear end of the adsorption column, a three-way ball valve 21, a gas storage tank 22, a gas pipeline vacuum pump 23, a gas pipeline vacuum pump valve 24, a mass spectrometer valve 25, a mass spectrometer 26, a temperature conducting tube 27, a temperature conducting valve 28, a temperature storage metal block 29, and a glass fiber 30.

[0047] Figure 2 (a) Side view, (b) front view, and (c) oblique top view of the disc-type adsorption column.

[0048] Figure 3 The device of the present invention was used to test the dynamic column penetration curves of porous carbon for H2 / D2 mixed gas at 40K, 60K and 77K.

[0049] Figure 4 Temperature-programmed desorption curves of H2 / D2 starting from (a) 40K, (b) 60K, and (c) 77K after the breakthrough experiment. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0051] Example 1

[0052] As attached Figure 1As shown: A device for a rapid isotope gas low-temperature adsorption separation system, comprising an isotope gas control system, a low-temperature control system, an adsorption column, a temperature storage system, and a gas detection system; the isotope gas control system includes an isotope gas, a purge gas, and a gas mixing chamber 5, wherein the isotope gas is connected to the inlet of the gas mixing chamber 5 via a pressure reducing valve 1, a gas dryer 2, a gas mass flowmeter 3, and an air inlet valve 4, respectively; the outlet of the gas mixing chamber 5 is connected to a stop valve 7, and an exhaust pipe is provided between the outlet of the gas mixing chamber and the stop valve 7, and the exhaust pipe is provided with an exhaust valve 6;

[0053] The low-temperature control system includes a refrigerator 18, a temperature controller 19 and a vacuum cover 12. The upper part of the cold head 17 of the refrigerator 18 is wrapped with several turns of gas pre-cooling pipe 15. The stop valve 7 is connected to the lower end of the pre-cooling pipe 15 through the solenoid valve 8. The purge gas is connected to the pipeline between the stop valve 7 and the solenoid valve 8 through the pressure reducing valve 1, the gas dryer 2, the gas mass flow meter 3 and the air inlet valve 4. The upper end of the pre-cooling pipe 15 is connected to the air inlet of the adsorption column 16. The adsorption column 16 is placed on the cold head. The temperature controller 19 is connected to the cold head 17. The cold head 17 and the adsorption column 16 are placed in the vacuum cover 12. To prevent energy leakage; when performing low-temperature control, the temperature controller 19 is connected to the cold head 17, and the target temperature is kept constant by turning on the refrigerator 18 and controlling the voltage output to control the temperature of the cold head. The low-temperature temperature can be controlled in the range of 4.2-300K, and the cooling rate can be controlled in the range of 0.5-5K / min; and the temperature controller 19 can also control the cold head temperature by controlling the voltage output to achieve constant target temperature and programmed heating to achieve high-temperature control. The high-temperature temperature can be controlled in the range of 300-800K, and the heating rate can be controlled in the range of 0.5-10K / min.

[0054] The temperature storage system is used for temperature pre-storage, and includes a temperature storage metal block 29 and a vacuum cover 12. The temperature storage metal block 29 is connected to the cold head 17 through a temperature conducting pipe 27. A temperature conducting valve 28 is provided on the temperature conducting pipe 27. The opening and closing of the cold or heat transport between the temperature storage metal block 29 and the cold head 17 is achieved by controlling the temperature conducting valve 28. The temperature storage metal block 29 is respectively connected to the refrigerator 18, the temperature controller 19 and the temperature sensor 14 for heating / cooling and controlling the temperature. The temperature storage metal block 29, the temperature conducting pipe 27 and the temperature conducting valve 28 are placed in the vacuum cover 12 to prevent energy leakage. The refrigerator 18 and the temperature controller 19 are used for pre-cooling control of the temperature storage metal block 29. The temperature controller 19 is used Regarding the pre-temperature control of the heat storage metal block 29, the heat storage metal block 29 can also perform pre-cold storage (recovery) by recovering the energy of the cold head; the heat storage metal block 29 can store a temperature range of 10-500K, and the cold or heat of the heat storage metal block 29 is quickly introduced into the cold head 17 by controlling the switch of the temperature conducting valve 28. After the energy exchange with the cold head 17 is completed, the temperature conducting valve 28 is closed; the heat storage metal block 29 is wrapped with glass fiber 30 to prevent energy leakage; the temperature conducting valve 28 is a mechanical piston-type temperature conducting metal. When rapid cooling or heating is required, the temperature conducting metal in the temperature conducting valve 28 will be connected to the temperature conducting pipe 27. When not required, the temperature conducting pipe 27 is disconnected by mechanically moving the temperature conducting metal;

[0055] The gas detection system includes a mass spectrometer; the gas outlet of the adsorption column 16 is connected to a gas storage tank 22, a mass spectrometer 26 and a gas pipeline vacuum pump 23 through a three-way ball valve 21. The gas pipeline vacuum pump 23 is used to adjust the adsorption pressure of the gas in the adsorption column. The pressure adjustment range is 0.0001-100kPa;

[0056] The adsorption column 16 is a packed fixed-bed adsorption column made of pure copper and constructed in a disc-shaped structure. It features wing-like structures on both sides, and a flat bottom structure to increase its contact surface with the cold head. The wing-like structures are fixedly connected to the cold head 17 via screws. A gasket is located at the bottom of the column. The gasket is an ultra-thin indium sheet with excellent ductility and thermal / cold conductivity, minimizing contact problems between the column and the cold head due to unevenness. The adsorption column has a length of 5-1000 cm and a radius of 0.6-200 cm. The cold head 17 is cylindrical with a radius of 8-1100 cm. The heat storage metal block is a rectangular parallelepiped, and its dimensions can be adjusted based on the size of the cold head. The length is 8-1100 cm, and the ratio of length to width or height ranges from 0.1-1:0.05-0.5.

[0057] The adsorption column 16 and cold head 17 are each equipped with two temperature detectors 14: a low-temperature detector and a high-temperature detector. The low-temperature detector detects temperatures at or below 300K, while the high-temperature detector detects temperatures above 300K. The adsorbent filled in the adsorption column 16 can be one or more of the following: metal oxides, non-metal oxides, inorganic salts, porous carbon, zeolite molecular sieves, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), hydrogen-bonded organic frameworks (HOFs), and porous polymers (POPs). Adsorbent regeneration methods include purge regeneration, high-temperature regeneration, vacuum regeneration, or high-temperature vacuum regeneration. Before entering the adsorbent 16, the gas is pre-cooled in a pre-cooling tube 15 wrapped around the cold head 17. The vacuum level of the adsorption column, pipeline, and vacuum chamber is monitored using a vacuum gauge 20 at the rear end of the adsorption column and a pressure gauge 13 inside the vacuum hood. The pressure gauge 13 inside the vacuum hood is connected to the vacuum hood 12 in the low-temperature control system and the heat storage system. The vacuum gauge 20 at the rear end of the adsorption column is placed at the gas outlet of the adsorption column. The vacuum hood 12 is insulated with double-layer stainless steel.

[0058] The vacuum housing 12 is connected to the vacuum pump 10 via the vacuum housing vacuum pump valve 9. A drain valve 11 is provided on the vacuum housing 12. This vacuum protects the energy storage system and the cryogenic system. When the adsorbent needs to be replaced, the drain valve 11 is opened to return the pressure to normal, and then the vacuum housing 12 is opened to replace the adsorbent.

[0059] Example 2

[0060] Using the apparatus of Example 1, taking hydrogen isotope (H2 / D2) separation as an example, the specific steps for performing low-temperature dynamic gas separation with porous carbon material as an adsorbent are as follows:

[0061] Step 1: Turn on the refrigerator 18 and the temperature controller 19 connected to the metal temperature storage block 29 to pre-cool the metal temperature storage block 29 and set the temperature to 30K. During the pre-cooling process, steps 2 and 3 can be performed.

[0062] Step 2: Regenerate the porous carbon adsorbent in vacuum at 200°C for more than 6 hours, then load the adsorbent into the adsorption column 16, and seal the air inlet and outlet with porous alumina gaskets and quartz wool; then fix the adsorption column 16 filled with the adsorbent to the cold head 17 and connect it to the pipeline;

[0063] Step 3: Then open the purge gas or gas pipeline vacuum pump 23 and the gas pipeline vacuum pump valve 24 to purge or vacuum the adsorbent to remove impurities in the adsorbent;

[0064] Step 4: Install the vacuum cover 12, confirm that the air inlet valve 11 of the vacuum cover 12 is closed, open the vacuum pump 10 and the air inlet valve 11 of the vacuum cover, and reduce the vacuum degree in the vacuum cover cavity to below 1 Pa and continue to evacuate for more than 20 minutes;

[0065] Step 5: Turn on the refrigerator 18 and temperature controller 19 connected to the cold head 17, set the target temperature, and begin cooling. This embodiment sets three temperatures: 40K, 60K, and 77K. During the cooling process, the purge gas or vacuum is maintained in operation. When the target temperature is reached, close the gas pipeline vacuum pump valve 24 or the purge gas inlet valve 4. The temperature and pressure within the adsorption column are monitored in real time via the temperature sensor 14 and the vacuum gauge 20 at the rear end of the adsorption column. Before cooling begins, the thermal conduction valve 28 of the heat storage system can be opened, and the heat storage metal block 29, which stores cold energy, can be connected to the cold head 17 via the thermal conduction pipe 27. This allows the cold energy to be quickly transferred to the cold head, thereby achieving rapid cooling of the adsorption column on the cold head. When the temperature sensor 14 values ​​of the cold head and the heat storage metal block are consistent, close the thermal conduction valve 28, ending the rapid cooling process and continuing the above cooling process. Since the adsorption column is loaded and removed at room temperature during operation, the refrigerator 18 of the temperature storage module can be turned on in advance to pre-cool the temperature storage metal block 29. The pre-cooling temperature can be calculated based on the actual adsorption column operating temperature.

[0066] Step 6: After closing the gas pipeline vacuum pump valve 24 or the purge gas inlet valve 4, open the gas mass flowmeter 3, use the pressure reducing valve 1 to adjust the isotope gas inlet pressure to the target pressure, open the inlet valve 4 to allow the isotope gas to enter the mixing chamber 5. When the mixed gas is not very stable or when cleaning the mixing chamber 5 and the previous pipeline, open the drain valve 6 and close the mixing chamber stop valve 7 to drain the above gas.

[0067] Step 7: When the temperature reaches the target temperature, there are no other gas impurities in the adsorption column, and the isotope mixture is ready, the test can begin. Before the test, close the exhaust valve 6 and the purge gas inlet valve 4. At the same time, open the mixing chamber stop valve 7 to allow the isotope mixture to enter the adsorption column 16 through the pre-cooling tube 15. Open the three-way ball valve 21 and the mass spectrometer valve 25, and close the vacuum valve 24. The adsorption column outlet gas will enter the mass spectrometer for detection. Since the mass spectrometer has a small gas demand, most of the gas will pass through valve 21 and enter the gas storage tank 22. When both components have broken through the adsorption column and the mass spectrometer signals of H2 and D2 no longer change, the isotope dynamic column penetration experiment is completed.

[0068] Step 8: After completing the above steps, open the gas line vacuum pump 23 and gas line vacuum pump valve 24, close the inlet valve 4, the gas mixing chamber shutoff valve 7, and the solenoid valve 8, and raise the temperature of the adsorption column to 473K to regenerate the adsorbent in a high-temperature vacuum. Repeat the above low-temperature dynamic gas separation test with the regenerated adsorbent to perform an adsorption column cycle experiment, such as dynamic column penetration separation of gas mixtures at other temperatures or with different isotopes.

[0069] There are two aspects to the high-temperature regeneration of the adsorbent. 1. Before the adsorption column is heated up, the adsorption column can be quickly heated up through the temperature storage system. The temperature controller 19 connected to the metal temperature storage block 29 is turned on to pre-heat the metal temperature storage block 29 and raise the temperature of the temperature storage block 29 to 500K. At this time, the temperature conduction valve 28 is opened to connect the heat storage metal block 29 with heat storage to the cold head 17 through the temperature conduction pipe 27, and the heat is quickly transferred to the cold head 17, thereby realizing the rapid heating of the adsorption column on the cold head 17. When the values ​​of the temperature sensors 14 of the cold head 17 and the temperature storage metal block 29 are consistent, the temperature conduction valve 28 is closed. At this time, the rapid heating process ends, and the temperature is then increased through the temperature controller 19 connected to the cold head 17 to continue to further heat and regenerate the adsorption column.

[0070] 2. After the low-temperature dynamic gas separation test is completed, but before the adsorption column is heated, the thermal conduction valve 28 of the thermal storage system is opened. At this point, the thermal storage metal block 29, which has a higher temperature than the cold head, is connected to the cold head 17 via the thermal conduction tube 27. This rapidly transfers the cold energy from the cold head 17 to the thermal storage metal block 29, thereby recovering the cold energy from the cold head 17. When the temperature sensors 14 of the cold head and the thermal storage metal block match, the thermal conduction valve 28 is closed, and the cold energy recovery process ends. The recovered cold energy is used for the next rapid cooling process. After recovery, the temperature of the adsorption column has risen, effectively heating the adsorption column rapidly. The temperature controller 19 connected to the cold head 17 then raises the temperature, allowing the column to continue to be regenerated by further heating. When the in-situ regeneration of the adsorption column is complete and the next round of testing is underway, the cold energy recovered from the thermal storage metal block can be transferred back to the cold head for subsequent adsorption column cycling experiments. For example, after testing at 40K, this cycle can be repeated for subsequent 60K and 77K cycles.

[0071] Attachment Figure 3 It is the dynamic column penetration curve of H2 / D2 mixed gas at 40K, 60K and 77K. Figure 2 As can be seen, the adsorption capacity of the adsorbent increases as the dynamic breakthrough temperature decreases. Due to the enhanced quantum effect at low temperatures, the separation time of H2 and D2 gradually increases with decreasing temperature. Furthermore, the roll-up of the column breakthrough curve caused by the competitive adsorption of H2 and D2 becomes increasingly apparent with decreasing temperature.

[0072] Example 3

[0073] In order to further determine the selectivity of the adsorbent in the adsorption column for H2 / D2, this device can be used to perform temperature-programmed desorption to observe the strength of the adsorbent's interaction with H2 / D2.

[0074] After step seven in Example 2, open the purge gas mass flowmeter 3, purge gas inlet valve 4, and drain valve 6, and close the gas mixing chamber shut-off valve 7. At this point, the purge gas will clean the easily desorbed components in the adsorption column 16 and the mixed gas in the pipelines connected to the front and rear of the adsorption column at the target low temperature. Then, set the cold head heating program to increase the temperature to 200K at a rate of 3°C / min. During the heating, the porous material in the adsorption column 16 will selectively desorb the adsorbed isotope gas, and the purge will bring the desorbed isotope gas into the mass spectrometer. Finally, use a mass spectrometer to detect the gas purged from the adsorption column. At this time, open the three-way ball valve 21 to divert the large flow of purge gas.

[0075] Attachment Figure 3 It is the low temperature programmed desorption curve after the dynamic column penetration curve of H2 / D2 mixture at 40K, 60K and 77K. Figure 3 It can be seen that the concentration of desorbed deuterium increases with decreasing temperature, which is consistent with the results of the dynamic breakthrough curve. At 40K, the purity of D2 can reach 89.6%.

Claims

1. A low-temperature adsorption separation system for isotope gases, characterized by: Including isotope gas control system, low temperature control system, adsorption column and gas detection system; The isotope gas control system comprises isotope gas and a gas mixing chamber (5), wherein the isotope gas is respectively connected to the inlet of the gas mixing chamber (5); The low-temperature control system includes a refrigerator (18), a temperature controller (19) and a vacuum cover (12); a plurality of gas pre-cooling tubes (15) are wound around the cold head (17) of the refrigerator (18); the outlet of the gas mixing chamber (5) is connected to the lower end of the pre-cooling tube (15); the upper end of the pre-cooling tube (15) is connected to the air inlet of the adsorption column (16); the adsorption column (16) is placed on the cold head (17); the temperature controller (19) is connected to the cold head (17); the cold head (17) and the adsorption column (16) are placed in the vacuum cover (12); the adsorption column (16) and the cold head (17) are each provided with a temperature sensor (14); the low-temperature controllable range is 4.2-300 K; the gas detection system includes a mass spectrometer (26); the mass spectrometer (26) is connected to the air outlet of the adsorption column (16); The isotope gas control system further includes a purge gas, and the outlet of the gas mixing chamber (5) is connected to the purge gas and then to the lower end of the pre-cooling tube (15); the gas outlet of the adsorption column (16) is connected to the gas storage tank (22), the mass spectrometer (26) and the gas pipeline vacuum pump (23) through a three-way ball valve (21); The invention also includes a temperature storage system for temperature pre-storage, including a temperature storage metal block (29) and a vacuum cover (12), wherein the temperature storage metal block (29) is connected to the cold head (17) through a temperature conducting pipe (27), and a temperature conducting valve (28) is provided on the temperature conducting pipe (27). By controlling the temperature conducting valve (28), the opening and closing of the cold or heat transport between the temperature storage metal block (29) and the cold head (17) are realized, and the temperature storage metal block (29) is respectively connected to the refrigerator (18), the temperature controller (19) and the temperature sensor (14), and the temperature storage metal block (29) and the temperature conducting pipe (27) are placed in the vacuum cover (12).

2. The isotope gas low-temperature adsorption separation system according to claim 1, characterized in that: The adsorption column (16) is a disc-type adsorption column, with wing-like structures on both sides of the adsorption column. The bottom of the butterfly-type adsorption column is a flat plate structure to increase its contact surface with the cold head. The wing-like structure in the disc-type adsorption column is fixedly connected to the cold head (17) by screws.

3. A separation method of the separation system according to any one of claims 1 to 2, characterized in that: Including isotope low temperature dynamic column breakthrough test, including the following steps: S1: fresh adsorbent is loaded into the adsorption column (16), and then the adsorption column (16) filled with the adsorbent is fixed to the cold head (17) and connected to the pipeline; S2 purges or vacuums the adsorbent to remove impurities from the adsorbent; S3: Install the vacuum cover (12), reduce the vacuum degree in the cavity of the vacuum cover (12) to below 1 Pa, and then continue to evacuate for more than 20 minutes; S4 turns on the refrigerator (18) and the temperature controller (19) connected to the cold head (17), sets the target temperature and starts cooling, and keeps the purge gas or vacuum running during the cooling process; when the target temperature is reached, stops the purge or vacuum; S5 first introduces pure component isotope gases into the gas mixing chamber for mixing, and then passes them into the adsorption column that has been cooled to the target temperature to achieve adsorption and separation of the isotope gases. The isotope gas concentration at the outlet of the adsorption column is detected by mass spectrometry to determine whether the adsorbent has the dynamic separation performance of the isotope gases.

4. The separation method according to claim 3, wherein: The method further includes performing rapid cooling before cooling: turning on the refrigerator (18) and the temperature controller (19) connected to the metal temperature storage block (29) to pre-cool the metal temperature storage block (29); the pre-cooling temperature is calculated based on the actual use temperature of the adsorption column, so that the temperature is pre-stored; the temperature guide valve (28) is opened to connect the temperature storage metal block (29) with cold energy to the cold head (17) through the temperature guide pipe (27); the cold energy is quickly transferred to the cold head (17), thereby achieving rapid cooling of the adsorption column (16) on the cold head (17); when the values ​​of the temperature sensors (14) of the cold head (17) and the temperature storage metal block (29) are consistent, the temperature guide valve (28) is closed, and the rapid cooling process ends.

5. The separation method according to claim 3 or 4, wherein: The method also includes opening the temperature conducting valve (28) after the test to transfer the cold energy of the cold head (17) to the metal temperature storage block (29) through the temperature conducting tube (27) for cold energy recovery, and performing subsequent isotope low-temperature dynamic column breakthrough test.

6. The separation method according to claim 5, wherein: It also includes low temperature program thermal desorption test, including the following steps: After the isotope low-temperature dynamic column breakthrough test is completed, S1 opens the purge gas to enter the adsorption column (16) to purge the adsorbent, and the concentration of the desorbed isotope is monitored online by mass spectrometry (26); S2 When the adsorbent surface and the weakly interacting isotopes are purged clean, the adsorption column is subjected to programmed temperature increase. During the temperature increase, the purge gas continuously purges the adsorbent, and the mass spectrometer (26) monitors the isotope gas desorbed by the temperature increase online to obtain a low-temperature programmed temperature desorption curve of the isotope gas in the adsorbent, which is used to determine the interaction force and adsorption site between the adsorbent and the isotope gas.

7. The separation method according to claim 3 or 4, wherein: Also included is the regeneration of the adsorbent after completion of the isotope low temperature dynamic column breakthrough test by purge, high temperature, vacuum, or high temperature vacuum.

8. The separation method according to claim 7, wherein: During high-temperature or high-temperature vacuum regeneration, the method also includes rapid heating before heating: opening the temperature controller (19) connected to the metal temperature storage block (29) to preheat the metal temperature storage block (29), the preheating temperature is calculated according to the actual use temperature of the adsorption column, so that heat is pre-stored, opening the temperature conducting valve (28) to connect the heat storage metal block (29) with heat storage to the cold head (17) through the temperature conducting pipe (27), and quickly transferring heat to the cold head (17), thereby achieving rapid heating of the adsorption column (16) on the cold head (17), when the values ​​of the temperature sensors (14) of the cold head (17) and the temperature storage metal block (29) are consistent, closing the temperature conducting valve (28), and the rapid heating process ends at this time; or opening the temperature conducting valve (28) to transfer the coldness of the cold head (17) to the metal temperature storage block (29) through the temperature conducting pipe (27), and at the same time, the temperature of the adsorption column (16) has risen, which is equivalent to rapidly heating the adsorption column (16).

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