A three-stage cryogenic pump device with GM refrigerator as cold source

Abstract

The application discloses a kind of three-stage cryogenic pump devices with GM refrigerator as cold source, including gas inlet pipeline, first adsorption unit, second adsorption unit and gas pumping unit connected with first adsorption unit and second adsorption unit, the gas inlet pipeline is connected with first adsorption unit, the first adsorption unit, second adsorption unit are each provided with independent sealed vacuum cavity and GM refrigerator located in two the cavity, two the cavity structure is connected by pipeline.The application, by setting two GM refrigerators, and separately placed in two vacuum cavities, and setting plug valve between two vacuum cavities, by primary cold plate, secondary cold plate and tertiary cold plate are placed in two independent vacuum cavities, both can realize independent adsorption and fractional analysis of mixed gas to tertiary cold plate, can also reduce system scale, reduce system construction cost.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, and more specifically to a three-stage cryogenic pump device using a GM refrigerator as a cold source. Background Technology

[0002] In the toroidal chamber of a fusion reactor, as the fusion reaction proceeds, deuterium and tritium are gradually consumed, while the amount of helium produced gradually increases. The accumulation of helium and other impurity gases causes the plasma to gradually cool. Therefore, to ensure the fusion reaction continues, exhaust gas (used combustion gas) must be continuously extracted from the toroidal chamber for purification. Because the deuterium-tritium reaction rate in current fusion devices is very low, a large amount of unreacted deuterium and tritium exists in the exhaust gas. From a safety, environmental, and economic perspective, the exhaust gas must be treated to recover the deuterium-tritium fuel. The three-stage cryogenic pump uses a GM refrigerator as the cold source and utilizes the principle of low-temperature condensation and adsorption to treat the exhaust gas. This concept divides the cryogenic pump into three stages. Based on the different condensation and vaporization points of the discharged ash gas, the gas is separated. The specific process is as follows: the first-stage cold plate provides a temperature of 80K for condensing water, hydrocarbons, and carbon oxides; the second-stage cold plate provides a temperature of 15-22K for condensing and adsorbing hydrogen isotopes; and the third-stage cold plate provides a temperature of 4.5K for adsorbing helium. The process of desorption is the reverse of the adsorption process. When the third-stage cold plate is heated to about 30K, helium desorption can be completed; when the second-stage cold plate is heated to about 110K, hydrogen and its isotopes can be desorbed; and when the first-stage cold plate is heated to about 300K, water, hydrocarbons, and carbon oxides can be desorbed. The desorbed gas is transferred to the corresponding collection tank by the pump set, thereby achieving the primary separation of the mixed gas.

[0003] The existing patent document with patent publication number CN107993733B discloses a three-stage cryogenic pump treatment device and method for radioactive exhaust gas from a fusion reactor. The treatment device includes a primary refrigeration unit, a secondary refrigeration unit, a tertiary refrigeration unit, a radiation shielding box, and a vacuum chamber. The separation and recovery of radioactive exhaust gas from the fusion reactor plasma is achieved through a series of steps, including pre-vacuuming of the separation system, primary condensation of the radioactive exhaust gas, secondary condensation of the radioactive exhaust gas, tertiary condensation-adsorption of the radioactive exhaust gas, tertiary desorption of the radioactive exhaust gas, secondary desorption of the radioactive exhaust gas, primary desorption of the radioactive exhaust gas, and simultaneous heating and desorption of the radioactive exhaust gas in multiple stages.

[0004] It employs three two-stage GM refrigerators placed within a single chamber to achieve three-stage cold plate temperatures. However, the main drawback of this single-chamber structure with three refrigerators in the same chamber is that it's difficult to achieve independent adsorption between the secondary and tertiary cold plates. Since the tertiary cold plate also exhibits excellent adsorption properties for hydrogen and its isotopes, it's challenging to achieve independent adsorption of hydrogen (and its isotopes) and helium without physical isolation between the secondary and tertiary cold plates. Even if the three GM refrigerators are placed in three separate chambers separated by valves, independent adsorption and graded desorption of the mixed gas can be achieved relatively well. However, using three refrigerators increases the system size and cost. Summary of the Invention

[0005] The technical problem to be solved by this invention is how to achieve independent adsorption and graded desorption of the mixed gas by the three-stage cold plate, while reducing the system size and lowering the system construction cost.

[0006] The present invention solves the above-mentioned technical problems through the following technical means: a three-stage cryogenic pump device using a GM refrigerator as a cold source, comprising an inlet pipe, a first adsorption unit, a second adsorption unit, and a gas pumping unit connected to the first adsorption unit and the second adsorption unit. The inlet pipe is connected to the first adsorption unit. The first adsorption unit and the second adsorption unit are each provided with an independent and sealed vacuum chamber and a GM refrigerator located in each of the two chambers respectively. The two chamber structures are connected by a pipe, and a gate valve is provided on the pipe. The cold plate of the first adsorption unit includes a primary cold plate and a secondary cold plate connected to the cold head of the refrigerator. The cold plate of the second adsorption unit includes a tertiary cold plate connected to the cold head of the refrigerator. Activated carbon is provided on both the secondary cold plate and the tertiary cold plate.

[0007] By setting up two GM refrigerators and placing them separately in two vacuum chambers, with a gate valve installed between the two vacuum chambers, and placing the primary, secondary, and tertiary cold plates in the two independent vacuum chambers respectively, it is possible to achieve independent adsorption and graded desorption of the mixed gas by the tertiary cold plate, while also reducing the system size and construction cost. Through the setting of the vacuum chambers, the refrigerator cold head, primary cold plate, secondary cold plate, and tertiary cold plate can all be insulated from the outside environment.

[0008] As a preferred technical solution, the first adsorption unit includes a first two-stage GM refrigerator. The first-stage cold head of the first two-stage GM refrigerator is connected to the first-stage cold plate, and the second-stage cold head of the first two-stage GM refrigerator is connected to the second-stage cold plate. The first-stage cold plate covers the outside of the second-stage cold plate. Activated carbon is adhered to the back of the second-stage cold plate, which can adsorb hydrogen and its isotope gases at low temperatures. The first-stage cold plate is connected to a vacuum chamber. Since the first-stage cold plate covers the outside of the second-stage cold plate, after the mixed gas enters the vacuum chamber, it first exchanges heat with the first-stage cold plate and then with the second-stage cold plate. Therefore, the adsorption order is also that the gas is first condensed by the first-stage cold plate and then adsorbed by the second-stage cold plate.

[0009] As a preferred technical solution, the first adsorption unit further includes a first heater, a first temperature sensor, a second heater, and a second temperature sensor. The first-stage cold head is provided with a first heater and a first temperature sensor, and the second-stage cold plate is provided with a second heater and a second temperature sensor.

[0010] As a preferred technical solution, it also includes a control system, which is electrically connected to the first heater, the first temperature sensor, the second heater, and the second temperature sensor, and can precisely control the temperature of the first-stage cold plate and the second-stage cold plate at any temperature between 50K and 300K.

[0011] As a preferred technical solution, the second adsorption unit includes a second two-stage GM refrigerator and a cold shield. The cold shield is connected to the first-stage cold head of the second two-stage GM refrigerator, and the third-stage cold plate is connected to the second-stage cold head of the second two-stage GM refrigerator. The cold shield is connected to the vacuum chamber and is placed on the outside of the third-stage cold plate. Activated carbon is adhered to the back of the third-stage cold plate. By setting up the cold shield, the radiative heat transfer from the environment to the third-stage cold plate is reduced, which is beneficial to increasing the cooling capacity of the second-stage cold head. The refrigerator cold head, cold shield, and third-stage cold plate are insulated from the outside environment by vacuum.

[0012] As a preferred technical solution, the second adsorption unit further includes a third heater, a third temperature sensor, a fourth heater, and a fourth temperature sensor. The cold screen is provided with the third heater and the third temperature sensor, and the three-stage cold plate is provided with the fourth heater and the fourth temperature sensor. The control system is electrically connected to the third heater, the third temperature sensor, the fourth heater, and the fourth temperature sensor.

[0013] As a preferred technical solution, the primary cold plate, secondary cold plate, and tertiary cold plate are all made of oxygen-free copper. Copper has a high thermal conductivity, so the temperature control accuracy and temperature uniformity are very good, which is more conducive to gas adsorption and desorption.

[0014] As a preferred technical solution, the top of the primary cold plate is provided with a herringbone-shaped radiation baffle. Before the mixed gas enters the secondary cold plate from the top of the primary cold plate, it will undergo several reflections and will not directly hit the secondary cold plate. During the reflection process, the mixed gas can be cooled down by sufficient heat exchange, so that most of the impurity gases such as hydrocarbons and carbon oxides are condensed and captured by the primary cold plate.

[0015] As a preferred technical solution, the gas extraction unit includes a gas extraction pipeline, a circulating vacuum pump, and a vacuum pipeline. One end of the gas extraction pipeline is connected to the first adsorption unit and the second adsorption unit respectively, and the other end is connected to an external gas storage device through the circulating vacuum pump. The vacuum pipeline is equipped with a vacuum valve and a vacuum pump.

[0016] As a preferred technical solution, control valves are provided on the air inlet pipe, the gas extraction pipe and the pipes connected to the first adsorption unit and the second adsorption unit.

[0017] The advantages of this invention are:

[0018] (1) In this invention, by setting up two GM refrigerators and placing them separately in two vacuum chambers, and setting a gate valve between the two vacuum chambers, and by placing the first-stage cold plate, the second-stage cold plate and the third-stage cold plate in two independent vacuum chambers respectively, it is possible to achieve independent adsorption and graded desorption of the mixed gas by the third-stage cold plate, and also to reduce the system size and reduce the system construction cost. By setting up the vacuum chambers, the refrigerator cold head, the first-stage cold plate, the second-stage cold plate and the third-stage cold plate can all be insulated from the outside.

[0019] (2) In this invention, by using an electrical connection between the control system, the first heater, the first temperature sensor, the second heater, and the second temperature sensor, the temperature of the first-stage cold plate and the second-stage cold plate can be precisely controlled between 50K and 300K. Similarly, the temperature of the cold screen and the third-stage cold plate can be controlled.

[0020] (3) In this invention, by setting up a cold screen, the radiative heat transfer of the environment to the three-stage cold plate is reduced, which is beneficial to increasing the cooling capacity of the two-stage cold head. The cold head, cold screen, and three-stage cold plate of the refrigerator are insulated from the outside by means of vacuum.

[0021] (4) In this invention, by setting up the herringbone-shaped radiation baffle, the mixed gas will be reflected several times before entering the secondary cold plate from the top of the primary cold plate and will not directly hit the secondary cold plate. During the reflection process, the mixed gas can be cooled down by sufficient heat exchange, so that most of the impurity gases such as hydrocarbons and carbon oxides are condensed and captured by the primary cold plate. Attached Figure Description

[0022] Figure 1This is a schematic diagram of a three-stage cryogenic pump device using a GM refrigerator as a cold source, provided in an embodiment of the present invention.

[0023] Reference numerals: 1. First two-stage GM refrigerator; 2. First vacuum chamber; 3. First-stage cold plate; 4. First heater; 5. First temperature sensor; 6. Second-stage cold plate; 7. Second heater; 8. Second temperature sensor; 9. Second two-stage GM refrigerator; 10. Second vacuum chamber; 11. Cold shield; 12. Third heater; 13. Third temperature sensor; 14. Third-stage cold plate; 15. Fourth heater; 16. Fourth temperature sensor; 17. Gate valve; 18. First solenoid valve; 19. Second solenoid valve; 20. Third solenoid valve; 21. Circulating vacuum pump; 22. Vacuum angle valve; 23. Vacuum pump. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] See Figure 1 A three-stage cryogenic pump device using a GM refrigerator as a cold source includes an inlet pipe, a first adsorption unit, a second adsorption unit, a gas extraction unit connected to the first adsorption unit and the second adsorption unit, and a control system (in this embodiment, a temperature controller is used as an example). The inlet pipe is connected to the first adsorption unit and is used to input a mixed gas. The first adsorption unit and the second adsorption unit are each provided with an independent and sealed vacuum chamber and a GM refrigerator located in each of the two chambers. The two chamber structures are connected by a pipe with a gate valve 17. The cold plate of the first adsorption unit includes a primary cold plate 3 and a secondary cold plate 6 connected to the cold head of the refrigerator. The cold plate of the second adsorption unit includes a tertiary cold plate 14 connected to the cold head of the refrigerator. Activated carbon is provided on both the secondary cold plate 6 and the tertiary cold plate 14.

[0026] See Figure 1The first adsorption unit includes a first two-stage GM refrigerator 1, a first vacuum chamber 2, a first-stage cold plate 3, a first heater 4, a first temperature sensor 5, a second-stage cold plate 6, a second heater 7, and a second temperature sensor 8. All components are located within the first vacuum chamber 2. The first-stage cold head of the first two-stage GM refrigerator 1 is connected to the first-stage cold plate 3, and the second-stage cold head is connected to the second-stage cold plate 6. The first two-stage GM refrigerator 1 provides cooling for both the first-stage and second-stage cold plates, with a minimum temperature less than 50K. The first-stage cold plate 3 covers the outer side of the second-stage cold plate 6. Activated carbon is adhered to the back of the second-stage cold plate 6; this activated carbon is used to adsorb hydrogen and its isotopes at low temperatures. The first-stage cold plate 3 is connected to the vacuum chamber. The first-stage cold head is equipped with a first heater 4 and a first temperature sensor 5. The temperature controller uses the first temperature sensor 5 as feedback to adjust the output power of the first heater 4 to achieve automatic temperature control of the first-stage cold plate 3. The minimum temperature of the second-stage cold plate 6 is less than 10K. The second-stage cold plate 6 is equipped with a second heater 7 and a second temperature sensor 8. The temperature controller uses the second temperature sensor 8 as feedback to adjust the output power of the second heater 7 to achieve automatic temperature control of the second-stage cold plate 6. After the mixed gas enters the first vacuum chamber 2, it contacts the first-stage cold plate 3 and exchanges heat to the temperature of the first-stage cold plate (~80K). At this time, water, hydrocarbons and carbon oxides condense on the first-stage cold plate 3. The remaining gas enters the second-stage cold plate 6. Hydrogen and its isotopes are adsorbed by the second-stage cold plate 6 (~20K). Helium is not adsorbed and remains in the first vacuum chamber 2.

[0027] The second adsorption unit includes a second two-stage GM refrigerator 9, a second vacuum chamber 10, a cold shield 11, a third heater 12, a third temperature sensor 13, a three-stage cold plate 14, a fourth heater 15, and a fourth temperature sensor 16. All of these components are located within the second vacuum chamber 10. The second two-stage GM refrigerator 9 provides cooling to the cold shield 11 and the three-stage cold plate 14. The cold shield 11 is connected to the first-stage cold head of the second two-stage GM refrigerator 9, with a minimum temperature less than 50K. The cold shield 11 is equipped with the third heater 12 and the third temperature sensor 13. The temperature controller uses the third temperature sensor 13 as feedback to adjust the output power of the third heater 12 to achieve automatic temperature control of the cold shield 11. The cold shield 11 is used to reduce... Radial heat transfer between the three-stage cold plate 14 and the environment; the cold shield 11 is connected to the vacuum chamber and surrounds the outside of the three-stage cold plate 14; the three-stage cold plate 14 is connected to the second-stage cold head of the second double-stage GM refrigerator 9; the minimum temperature of the three-stage cold plate 14 is less than 4K; the three-stage cold plate 14 is equipped with a fourth heater 15 and a fourth temperature sensor 16; the temperature controller uses the fourth temperature sensor 16 as feedback to adjust the output power of the fourth heater 15 to achieve automatic temperature control of the three-stage cold plate 14; activated carbon is adhered to the back of the three-stage cold plate 14; the slide valve 17 can be opened to allow unadsorbed helium gas in the first vacuum chamber 2 to enter the second vacuum chamber 10 and be adsorbed by the three-stage cold plate 14 (~4.2K); the first-stage cold plate 3, the second-stage cold plate 6, and the third-stage cold plate 14 are all made of oxygen-free copper; copper has a high thermal conductivity, so the temperature control accuracy and temperature uniformity are very good, which is more conducive to gas adsorption and desorption.

[0028] See Figure 1 The top of the primary cold plate 3 and the cold screen 11 is equipped with a herringbone-shaped radiation baffle. Before the mixed gas enters the secondary cold plate 6 from the top of the primary cold plate 3, it will be reflected several times and will not directly hit the secondary cold plate 6. During the reflection process, the mixed gas can be cooled down by sufficient heat exchange, so that most of the impurity gases such as hydrocarbons and carbon oxides are condensed and captured by the primary cold plate 3. In the second vacuum chamber 10, before the helium gas enters the tertiary cold plate 14 from the top of the cold screen 11, it will be reflected several times and will not directly hit the tertiary cold plate 14. During the reflection process, the helium gas can be cooled down by sufficient heat exchange and is condensed and captured by the tertiary cold plate 14.

[0029] See Figure 1The gas extraction unit includes a gas extraction pipeline, a circulating vacuum pump 21, a vacuum extraction pipeline, a vacuum angle valve 22, and a vacuum pump 23. One end of the gas extraction pipeline is connected to the first adsorption unit and the second adsorption unit, respectively, and the other end is connected to an external gas storage device through the circulating vacuum pump 21. The vacuum extraction pipeline is equipped with a vacuum angle valve 22 and a vacuum pump 23. A first solenoid valve 18 is installed on the inlet pipeline, and a second solenoid valve 19 is installed on the pipeline connecting the gas extraction pipeline to the first adsorption unit. The gas extraction pipeline is connected to the second adsorption unit... A third solenoid valve 20 is installed on the pipeline. Before the device starts cooling down, the vacuum pump 23, the second solenoid valve 19, and the third solenoid valve 20 are opened to evacuate the first adsorption unit, the second adsorption unit, and the pipeline into a vacuum state. This removes impurity gases and provides an insulated working environment for the GM refrigeration unit. The temperature of the first-stage cold plate 3, the second-stage cold plate 6, and the third-stage cold plate 14 is controlled by graded temperature control. After the gas on the corresponding cold plate is desorbed, the desorbed gas is extracted by the circulating vacuum pump 21 in conjunction with the relevant solenoid valve switches and collected into the corresponding collection tank.

[0030] Operating method: Input the mixed gas through the intake pipe. After the mixed gas enters the first vacuum chamber 2, it contacts the first-stage cold plate 3 and exchanges heat to the temperature of the first-stage cold plate 3 (~80K). At this time, water, hydrocarbons and carbon oxides condense on the first-stage cold plate 3. The remaining gas enters the second-stage cold plate 6. Hydrogen and its isotopes are adsorbed by the second-stage cold plate 6 (~20K). Helium is not adsorbed and remains in the first vacuum chamber 2. At this time, open the gate valve 17. The helium that is not adsorbed in the first vacuum chamber 2 enters the second vacuum chamber 10 and is adsorbed by the third-stage cold plate 14 (~4.2K).

[0031] The gas desorption and collection process is as follows: (1) Control the temperature of the third-stage cold plate 14 to desorb helium, open the third solenoid valve 20 and the circulating vacuum pump 21 to pump the desorbed helium into the helium collection tank; (2) Close the third solenoid valve 20, control the temperature of the second-stage cold plate 6 to desorb hydrogen and its isotope gases, open the second solenoid valve 19 and the circulating vacuum pump 21 to pump the desorbed hydrogen and its isotope gases into the hydrogen collection tank; (3) Control the temperature of the first-stage cold plate 3 to desorb impurity gases such as water, hydrocarbons, and carbon oxides, open the second solenoid valve 19 and the circulating vacuum pump 21 to pump the desorbed impurity gases into the impurity gas collection tank.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-stage cryogenic pump device using a GM refrigerator as a cold source, comprising an inlet pipe, a first adsorption unit, and a second adsorption unit, characterized in that, It also includes a gas pumping unit connected to the first adsorption unit and the second adsorption unit. The gas inlet pipe is connected to the first adsorption unit. The first adsorption unit and the second adsorption unit are each provided with an independent and sealed vacuum chamber and a GM refrigerator located in each of the two chambers. The two chamber structures are connected by a pipe. The pipe is provided with a gate valve (17) for controlling the opening and closing of the two chamber structures. The cold plate of the first adsorption unit includes a primary cold plate (3) and a secondary cold plate (6) connected to the cold head of the refrigerator. The cold plate of the second adsorption unit includes a primary cold plate (3) and a secondary cold plate (6) connected to the cold head of the refrigerator. The three-stage cold plate (14) connected to the cold head of the cold machine is provided with activated carbon on both the second-stage cold plate (6) and the third-stage cold plate (14); the gas pumping unit includes a gas pumping pipeline, a circulating vacuum pump (21), and a vacuum pumping pipeline. One end of the gas pumping pipeline is connected to the first adsorption unit and the second adsorption unit respectively, and the other end is connected to an external gas storage device through the circulating vacuum pump (21). The vacuum pumping pipeline is provided with a vacuum angle valve (22) and a vacuum pump (23). The gas inlet pipeline, the gas pumping pipeline and the pipelines connected to the first adsorption unit and the second adsorption unit are all provided with control valves.

2. The three-stage cryogenic pump device using a GM refrigerator as a cold source according to claim 1, characterized in that, The first adsorption unit includes a first dual-stage GM refrigerator (1), the first stage cold head of the first dual-stage GM refrigerator (1) is connected to the first stage cold plate (3), the second stage cold head of the first dual-stage GM refrigerator (1) is connected to the second stage cold plate (6), and the first stage cold plate (3) covers the outside of the second stage cold plate (6). Activated carbon is adhered to the back of the second stage cold plate (6), and the first stage cold plate (3) is connected to the vacuum chamber.

3. A three-stage cryogenic pump device using a GM refrigerator as a cold source according to claim 2, characterized in that, The first adsorption unit also includes a first heater (4), a first temperature sensor (5), a second heater (7), and a second temperature sensor (8). The first-stage cold head is provided with the first heater (4) and the first temperature sensor (5), and the second-stage cold plate (6) is provided with the second heater (7) and the second temperature sensor (8).

4. A three-stage cryogenic pump device using a GM refrigerator as a cold source according to claim 3, characterized in that, It also includes a control system, which is electrically connected to the first heater (4), the first temperature sensor (5), the second heater (7), and the second temperature sensor (8).

5. A three-stage cryogenic pump device using a GM refrigerator as a cold source according to claim 4, characterized in that, The second adsorption unit includes a second dual-stage GM refrigerator (9) and a cold screen (11). The cold screen (11) is connected to the first-stage cold head of the second dual-stage GM refrigerator (9). The third-stage cold plate (14) is connected to the second-stage cold head of the second dual-stage GM refrigerator (9). The cold screen (11) is connected to the vacuum chamber and is wrapped around the outside of the third-stage cold plate (14). Activated carbon is adhered to the back of the third-stage cold plate (14).

6. A three-stage cryogenic pump device using a GM refrigerator as a cold source according to claim 5, characterized in that, The second adsorption unit also includes a third heater (12), a third temperature sensor (13), a fourth heater (15), and a fourth temperature sensor (16). The third heater (12) and the third temperature sensor (13) are provided on the cold screen (11), and the fourth heater (15) and the fourth temperature sensor (16) are provided on the three-stage cold plate (14). The control system is electrically connected to the third heater (12), the third temperature sensor (13), the fourth heater (15), and the fourth temperature sensor (16).

7. A three-stage cryogenic pump device using a GM refrigerator as a cold source according to claim 1, characterized in that, The first-stage cold plate (3), the second-stage cold plate (6), and the third-stage cold plate (14) are all made of oxygen-free copper.

8. A three-stage cryogenic pump device using a GM refrigerator as a cold source according to claim 2, characterized in that, The top of the primary cold plate (3) is provided with a herringbone-shaped radiation barrier.

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