High and low temperature control device for temperature swing adsorption separation of krypton-85 in atmosphere

Abstract

The invention discloses a high and low temperature control device for krypton-85 temperature swing adsorption separation in the atmosphere. The high and low temperature control device comprises a refrigerating machine, a helium compressor, a vacuum chamber, a vacuum pump, an activated carbon adsorption trap, a heating piece, a heat insulation piece and an adjusting assembly. The refrigerating machine is mounted on the vacuum chamber, a cold head of the refrigerating machine extends into the vacuum chamber, and the refrigerating machine is connected with the helium compressor; the adjusting assembly is arranged in the vacuum chamber, the heat insulation part is arranged on the adjusting assembly, the heating part is arranged on the heat insulation part and fixedly connected with the activated carbon adsorption trap, the activated carbon adsorption trap is arranged opposite to a cold head of the refrigerator, and the adjusting assembly drives the activated carbon adsorption trap to be attached to or separated from the cold head of the refrigerator; the vacuum pump is communicated with the vacuum chamber. The high and low temperature control device is simple in structure, and high and low temperature control in the krypton-85 temperature swing adsorption separation process can be rapidly and effectively achieved.

Description

Technical Field

[0001] This invention relates to the field of temperature control technology, and in particular to a high and low temperature control device for the temperature-variable adsorption and separation of krypton-85 in the atmosphere. Background Technology

[0002] Krypton-85 is a radioactive isotope of krypton with a half-life of approximately 10.76 years. It primarily originates from man-made emissions from nuclear power plants and nuclear fuel reprocessing plants. With the development of nuclear energy, krypton-85 has been accumulating in the atmosphere. To assess the environmental and public health impacts of the nuclear industry, environmental monitoring of krypton-85 in the atmosphere, especially around nuclear facilities and in gaseous effluents from these facilities, is necessary.

[0003] Because krypton is present in very small amounts in the air, approximately 1.14 ppm, monitoring krypton-85 requires the separation and enrichment of the sample gas. The conventional krypton separation and enrichment procedure is as follows: first, molecular sieves are used to remove water and carbon dioxide from the gas; then, coconut shell activated carbon is used at liquid nitrogen temperature (-196℃) to adsorb the purified nitrogen, oxygen, krypton, and methane; subsequently, helium is used for temperature-switching purging at dry ice-ethanol temperature (-80℃); finally, desorption is performed above 200℃, and the gas is then separated by a chromatographic column. Throughout this temperature-switching separation process, the activated carbon trap needs to withstand stable temperature control at ultra-low temperatures of -196℃ to -80℃ to 200℃. Simultaneously, to meet the requirements for separating large volumes (approximately 0.5 cubic meters) of air containing krypton, it is usually necessary to use two coconut shell activated carbon traps connected in series for krypton separation. These requirements pose a significant challenge to the high and low temperature control of the activated carbon traps.

[0004] To address the challenge of maintaining stable ultra-low and high temperatures in activated carbon traps during krypton separation and enrichment, Chinese Patent Application No. 201620921205.8 discloses a low-temperature adsorption-desorption device for krypton in air, and Chinese Patent Application No. 202411521770.0 discloses a liquid nitrogen thermostat and temperature control method for monitoring Kr-85 in gaseous effluents. Both of these methods employ a combination of liquid nitrogen and electric heating for high and low temperature control of the activated carbon traps. However, these methods consume a large amount of liquid nitrogen and have low automation. Chinese Patent Application No. 202022276419.3 discloses an electrically cooled sampling device that uses helium as a heat transfer medium and vacuuming to control the cooling and heating of each adsorption trap. However, this solution has a complex structure, requires multiple vacuum chambers, and utilizes helium for indirect cooling, resulting in low heat transfer efficiency and slow temperature control.

[0005] Therefore, the existing technology still needs to be improved and enhanced.

[0006] Invention Patent Content In view of the shortcomings of the prior art, the purpose of this invention is to provide a high and low temperature control device for temperature-switching adsorption and separation of krypton-85 in the atmosphere, which aims to solve the problems of complex structure and poor high and low temperature control effect of existing krypton-85 temperature-switching adsorption and enrichment devices.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A high-low temperature control device for temperature-dependent adsorption and separation of krypton-85 in the atmosphere includes: a refrigerator, a helium compressor, a vacuum chamber, a vacuum pump, an activated carbon adsorption trap, a heating element, a heat insulation element, and an adjustment assembly. The refrigerator is mounted on the vacuum chamber, with its cold head extending into the interior of the vacuum chamber. The refrigerator is connected to the helium compressor. The adjustment assembly is disposed within the vacuum chamber, the heat insulation element is disposed on the adjustment assembly, the heating element is disposed on the heat insulation element, and the heating element is fixedly connected to the activated carbon adsorption trap. The activated carbon adsorption trap is positioned opposite to the cold head of the refrigerator. The adjustment assembly causes the activated carbon adsorption trap to come into contact with or separate from the cold head of the refrigerator. The vacuum pump is connected to the vacuum chamber.

[0008] The helium compressor and the refrigerator are connected by two pipelines. One pipeline supplies compressed helium to the refrigerator, and the other pipeline returns depressurized helium to the helium compressor.

[0009] One-way valves and pressure gauges are installed on both pipelines connecting the helium compressor and the refrigeration unit.

[0010] The adjustment assembly includes a drive assembly and a stage. The drive assembly is used to move the activated carbon adsorption trap on the stage to fit or separate from the cold head of the refrigerator.

[0011] The stage is horizontally positioned inside the vacuum chamber. The cold head of the refrigerator extends into the vacuum chamber from the upper end. The drive assembly drives the upper end of the activated carbon adsorption trap on the stage to move vertically and either come into contact with or separate from the cold head of the refrigerator.

[0012] The activated carbon adsorption trap and the heating element are bonded and fixed together with thermally conductive adhesive.

[0013] The high and low temperature control device for temperature-dependent adsorption and separation of krypton-85 in the atmosphere also includes a temperature sensor disposed on the activated carbon adsorption trap.

[0014] The inner wall of the vacuum chamber is provided with a heat insulation layer, and a vacuum gauge is installed on the vacuum chamber to detect the vacuum level inside the vacuum chamber in real time.

[0015] Compared to existing technologies, this invention provides a high- and low-temperature control device for temperature-dependent adsorption and separation of krypton-85 in the atmosphere, comprising: a refrigerator, a helium compressor, a vacuum chamber, a vacuum pump, an activated carbon adsorption trap, a heating element, a heat insulation element, and an adjustment component; the refrigerator is mounted on the vacuum chamber, with its cold head extending into the interior of the vacuum chamber, and the refrigerator is connected to the helium compressor; the adjustment component is disposed within the vacuum chamber, the heat insulation element is disposed on the adjustment component, the heating element is disposed on the heat insulation element, and the heating element is fixedly connected to the activated carbon adsorption trap, the activated carbon adsorption trap being positioned opposite the cold head of the refrigerator, and the adjustment component causing the activated carbon adsorption trap to be in contact with or separate from the cold head of the refrigerator; the vacuum pump is connected to the vacuum chamber.

[0016] In this application, the regulating component drives the activated carbon adsorption trap to contact the cold head of the refrigerator, so that the activated carbon adsorption trap adsorbs krypton-85 under low temperature conditions to achieve the enrichment of krypton-85; the regulating component drives the activated carbon adsorption trap away from the cold head of the refrigerator and heats the activated carbon adsorption trap through the heating element to achieve the desorption of krypton-85 in the activated carbon adsorption trap; the structure is simple and can quickly and effectively achieve high and low temperature control in the krypton-85 temperature-switching adsorption and separation process. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the high and low temperature control device for temperature-variable adsorption and separation of krypton-85 in the atmosphere, provided by this invention patent.

[0018] Attached icon number 1. Refrigeration unit, 2. Helium compressor, 3. Vacuum chamber, 4. Vacuum pump, 5. Activated carbon adsorption trap, 6. Heating element, 7. Heat insulation element, 8. Adjustment component. Detailed Implementation

[0019] To make the purpose, technical solution, and effects of this invention patent clearer and more explicit, the following detailed description of this invention patent is provided with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this invention patent and are not intended to limit this invention patent.

[0020] It should be noted that when a component is referred to as being "mounted on," "fixed to," or "set on" another component, it can be directly on the other component or may have an intervening component present. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or may have an intervening component present.

[0021] It should also be noted that the directional terms such as left, right, up, and down in the embodiments of this invention are only relative concepts or are based on the normal use of the product, and should not be considered as restrictive.

[0022] This invention patent provides a high and low temperature control device for temperature-dependent adsorption and separation of krypton-85 in the atmosphere. Please refer to [link / reference]. Figure 1 The system includes: a refrigerator 1, a helium compressor 2, a vacuum chamber 3, a vacuum pump 4, an activated carbon adsorption trap 5, a heating element 6, a heat insulation element 7, and an adjustment assembly 8. The refrigerator 1 is mounted on the vacuum chamber 3, and the cold head of the refrigerator 1 extends into the interior of the vacuum chamber 3. The refrigerator 1 is connected to the helium compressor 2. The adjustment assembly 8 is disposed within the vacuum chamber 3. The heat insulation element 7 is disposed on the adjustment assembly 8. The heating element 6 is disposed on the heat insulation element 7, and the heating element 6 is fixedly connected to the activated carbon adsorption trap 5. The activated carbon adsorption trap 5 is disposed opposite to the cold head of the refrigerator 1. The adjustment assembly 8 drives the activated carbon adsorption trap 5 to be in contact with or separate from the cold head of the refrigerator 1. The vacuum pump 4 is connected to the vacuum chamber 3.

[0023] In this application, the regulating component 8 drives the activated carbon adsorption trap 5 to contact the cold head of the refrigerator 1, so that the activated carbon adsorption trap 5 adsorbs krypton-85 under low temperature conditions to achieve the enrichment of krypton-85; the regulating component 8 drives the activated carbon adsorption trap 5 away from the cold head of the refrigerator 1 and heats the activated carbon adsorption trap 5 through the heating element 6 to achieve the desorption of krypton-85 in the activated carbon adsorption trap 5; the structure is simple and can quickly and effectively achieve high and low temperature control in the krypton-85 temperature-switching adsorption and separation process. The refrigerator 1 is mounted on top of the vacuum chamber 3 via a vacuum-sealed flange, with the cold head of the refrigerator 1 extending into the vacuum chamber 3. The insulation component 7 is made of polytetrafluoroethylene, zirconia ceramic, or other insulating materials to prevent heat transfer from the heating element 6 to the regulating component 8, thus preventing heat loss and protecting the regulating component 8 from high and low temperature shocks. The insulation component 7 can be screwed onto the regulating component 8. The heating element 6 can be a heating rod (e.g., an armored heating rod), which is embedded in the groove of the insulation component 7. The upper surface of the heating rod is flush with the insulation component 7, ensuring that the insulation component 7 provides insulation and protects the regulating component 8 from shocks. Thermal shock; the activated carbon adsorption trap 5 is a cylindrical structure filled with 80-200 mesh coconut shell activated carbon. The surface roughness of its top plane in contact with the cold head of the refrigerator 1 is ≤Ra1.6 to ensure tightness during bonding; the vacuum pump 4 is a rotary vane type or molecular pump, connected to the vacuum chamber 3 via a metal bellows, with a flange at the connection point. A sealing ring is installed in the flange groove, and if necessary, a small amount of vacuum silicone grease is applied to the surface of the sealing ring to enhance the sealing performance at the connection point and ensure the stability of the vacuum level in the vacuum chamber 3. The specific connection structure between the metal bellows and the vacuum pump 4 and the vacuum chamber 3 is prior art and will not be described in detail here. In this application, the refrigerator 1 is a Gifford-McMahon refrigerator 1, which uses the adiabatic gas release expansion principle to achieve refrigeration. The specific structure and principle are prior art.

[0024] Furthermore, the helium compressor 2 is connected to the refrigerator 1 through two pipelines. One pipeline supplies compressed helium to the refrigerator 1, and the other pipeline returns depressurized helium to the helium compressor 2.

[0025] In this application, the helium compressor 2 is connected to the refrigerator 1 via a pressure-resistant stainless steel pipeline. Two pipes form a helium circulation path, supplying compressed helium to the refrigerator 1 as its working medium. The depressurized helium returns to the compressor for recompression and reuse, achieving helium circulation and ensuring the refrigerator 1 continuously and stably generates cooling capacity to meet the temperature requirements of the activated carbon adsorption trap 5 during the low-temperature adsorption stage. During the circulation process, some of the energy carried by the helium during depressurization and return can be recovered and reused by the compressor, reducing energy loss, improving the overall energy efficiency of the device, and lowering operating costs. The closed helium circulation pipeline effectively prevents helium leakage, maintains stable helium pressure and flow rate within the system, ensures stable cooling performance of the refrigerator 1, and thus guarantees the temperature control accuracy of the activated carbon adsorption trap 5, improving the efficiency and stability of krypton-85 separation. The principle and related structure of the helium compressor 2 in recovering depressurized helium, as well as the working principle and structure of the refrigerator 1, are prior art and will not be elaborated upon here. The accompanying drawings are only schematic diagrams showing the connection between the helium compressor 2 and the refrigerator 1, and do not show the two pipelines.

[0026] Furthermore, both the helium compressor 2 and the refrigerator 1 are equipped with one-way valves (not shown in the figure) and pressure gauges (not shown in the figure). The one-way valves on the pipelines prevent helium backflow, ensuring the stability of the helium circulation between the refrigerator 1 and the helium compressor 2, and avoiding a decrease in refrigeration efficiency due to gas backflow; the pressure gauges can monitor the pipeline pressure in real time, ensuring that the system operates within a safe pressure range and reducing the risk of equipment failure.

[0027] Furthermore, the adjustment component 8 includes a drive component and a stage. The drive component is used to drive the activated carbon adsorption trap 5 on the stage to contact or separate from the cold head of the refrigerator 1. The drive component can be a linear module composed of a servo motor, a ball screw, and a linear guide rail, connected by a coupling to form a transmission chain. The combination of the servo motor and the ball screw achieves high-precision drive, ensuring stable contact pressure between the activated carbon adsorption trap 5 and the cold head, and avoiding cold loss due to poor contact. The linear guide rail ensures smooth movement of the stage and prevents damage from collision between the activated carbon adsorption trap 5 and the cold head. The specific structure of the drive component is designed based on existing technology, and its principle and specific structure belong to existing technology. The drive component can be rigidly connected to the stage by bolts to meet the load-bearing requirements of components such as the activated carbon adsorption trap 5 and the heating element 6. Of course, the drive component can also adopt hydraulic or pneumatic transmission, which is not limited here, and its specific structure belongs to existing technology.

[0028] Furthermore, the stage is horizontally positioned inside the vacuum chamber 3, and the cold head of the refrigerator 1 extends into the vacuum chamber 3 from the upper end of the vacuum chamber 3. The driving assembly drives the upper end of the activated carbon adsorption trap 5 on the stage to move vertically and to come into contact with or separate from the cold head of the refrigerator 1.

[0029] In this embodiment, the refrigerator 1 is installed above the vacuum chamber 3, with the cold head of the refrigerator 1 extending into the vacuum chamber 3. The drive assembly is installed on the upper inner wall of the vacuum chamber 3. The stage is connected to the drive assembly and is horizontally positioned within the vacuum chamber 3. The cold head of the refrigerator 1 is located directly above the activated carbon adsorption trap 5. A heat insulation component 7, a heating component 6, and the activated carbon adsorption trap 5 are sequentially arranged on the stage. The drive assembly can drive the stage to move vertically, allowing the activated carbon adsorption trap 5 on the stage to contact or move away from the cold head of the refrigerator 1. When the device is working, the vacuum pump 4 is first turned on to evacuate the vacuum chamber 3, bringing it into a vacuum state (e.g., vacuum degree ≤ 1× 10⁻⁶). The process involves several steps: First, the helium compressor 2 and the refrigerator 1 begin operation, lowering the temperature of the cold head of the refrigerator 1 to -196°C. Then, the activated carbon adsorption trap 5 on the stage is moved upwards by the drive assembly until it is in close contact with the cold head of the refrigerator 1, further reducing its temperature to -196°C. After adsorption, the temperature of the activated carbon adsorption trap 5 is maintained at -80°C by adjusting the heating power of the heating element 6, providing a variable temperature purging range. Next, the drive assembly moves the activated carbon adsorption trap 5 downwards, separating it from the cold head of the refrigerator 1. The heating element 6 heats the activated carbon adsorption trap 5, rapidly raising its temperature from -80°C to 200°C in a short time, thus completing the desorption. This process separates the activated carbon adsorption trap 5 from the cold head of the refrigerator 1, preventing damage to the refrigerator 1 when the activated carbon adsorption trap 5 is heated to a high temperature.

[0030] Furthermore, the activated carbon adsorption trap 5 and the heating element 6 are bonded and fixed together using thermally conductive adhesive. Bonding the activated carbon and heating element 6 with thermally conductive adhesive improves heat transfer efficiency, allowing heat from the heating element 6 to be quickly transferred to the activated carbon adsorption trap 5, ensuring uniform and rapid heating.

[0031] Furthermore, the high and low temperature control device for the temperature-dependent adsorption and separation of krypton-85 in the atmosphere also includes a temperature sensor (not shown in the figure) disposed on the activated carbon adsorption trap 5. In this embodiment, the temperature sensor can be a thermocouple sensor or other temperature sensor with a probe. It can be fixed to the activated carbon adsorption trap 5 by means of thermally conductive adhesive (e.g., thermally conductive silicone, epoxy resin, etc.) or mechanical fixation (e.g., clamping, screw fixing, etc.) to ensure stable installation of the temperature sensor. A small hole (slightly larger than the diameter of the thermocouple) is reserved on the activated carbon adsorption trap 5. The probe of the temperature sensor is inserted into the activated carbon filling layer inside the activated carbon adsorption trap 5 through the small hole. The direct contact method allows the temperature sensor to respond quickly to the temperature change of the activated carbon adsorption trap 5, avoiding temperature measurement delay or deviation caused by poor contact. After insertion, the gap is sealed with a high-temperature resistant sealing material (such as ceramic sealant) to prevent gas leakage from affecting the adsorption efficiency. Of course, alternatively, a patch-type temperature sensor can also be used, which is bonded to the outer wall of the activated carbon adsorption trap 5 with thermally conductive adhesive.

[0032] Furthermore, the inner wall of the vacuum chamber 3 is provided with a heat insulation layer (not shown in the figure), and a vacuum gauge is installed on the vacuum chamber 3 to monitor the vacuum level inside the vacuum chamber 3 in real time. The heat insulation layer can be made of aerogel felt, which is adhered to the inner wall of the vacuum chamber 3 with high-temperature resistant adhesive. The aerogel felt heat insulation layer and the high vacuum environment form a double insulation, which can reduce the loss of cold energy. Together with the vacuum pump 4 to maintain the high vacuum environment, it further enhances the insulation effect and reduces the cooling energy consumption. The vacuum gauge monitors the vacuum level in real time to ensure that the vacuum chamber 3 is always in a low heat transfer state, ensuring the temperature stability of the activated carbon adsorption trap 5.

[0033] In summary, this invention provides a high-low temperature control device for temperature-dependent adsorption and separation of krypton-85 in the atmosphere, comprising: a refrigerator, a helium compressor, a vacuum chamber, a vacuum pump, an activated carbon adsorption trap, a heating element, a heat insulation element, and a mechanical motion device; the refrigerator is mounted on the vacuum chamber, with its cold head extending into the interior of the vacuum chamber, and the refrigerator is connected to the helium compressor; the mechanical motion device is disposed within the vacuum chamber, the heat insulation element is disposed on the mechanical motion device, the heating element is disposed on the heat insulation element, and the heating element is fixedly connected to the activated carbon adsorption trap; the activated carbon adsorption trap is disposed opposite to the cold head of the refrigerator, and the mechanical motion device drives the activated carbon adsorption trap to adhere to or separate from the cold head of the refrigerator; the vacuum pump is connected to the vacuum chamber.

[0034] In this application, a mechanical motion device drives the activated carbon adsorption trap to contact the cold head of the refrigerator, so that the activated carbon adsorption trap adsorbs krypton-85 under low temperature conditions to achieve the enrichment of krypton-85; the mechanical motion device drives the activated carbon adsorption trap away from the cold head of the refrigerator and heats the activated carbon adsorption trap through a heating element to achieve the desorption of krypton-85 in the activated carbon adsorption trap; the structure is simple and can quickly and effectively achieve high and low temperature control in the krypton-85 temperature-switching adsorption and separation process.

[0035] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solution and inventive concept of this patent, and all such substitutions or modifications should fall within the protection scope of the claims appended to this patent.

Claims

1. A high and low temperature control device for temperature-variable adsorption and separation of krypton-85 in the atmosphere, characterized in that, include: The system comprises a refrigerator, a helium compressor, a vacuum chamber, a vacuum pump, an activated carbon adsorption trap, a heating element, a heat insulation element, and an adjustment assembly. The refrigerator is mounted on the vacuum chamber, with its cold head extending into the interior of the vacuum chamber. The refrigerator is connected to the helium compressor. The adjustment assembly is located within the vacuum chamber, the heat insulation element is mounted on the adjustment assembly, and the heating element is mounted on the heat insulation element and fixedly connected to the activated carbon adsorption trap. The activated carbon adsorption trap is positioned opposite to the cold head of the refrigerator. The adjustment assembly causes the activated carbon adsorption trap to come into contact with or separate from the cold head of the refrigerator. The vacuum pump is connected to the vacuum chamber.

2. The high and low temperature control device for temperature-variable adsorption and separation of krypton-85 in the atmosphere according to claim 1, characterized in that, The helium compressor and the refrigerator are connected by two pipelines. One pipeline supplies compressed helium to the refrigerator, and the other pipeline returns depressurized helium to the helium compressor.

3. The high and low temperature control device for temperature-variable adsorption and separation of krypton-85 in the atmosphere according to claim 2, characterized in that, One-way valves and pressure gauges are installed on both pipelines connecting the helium compressor and the refrigeration unit.

4. The high and low temperature control device for temperature-variable adsorption and separation of krypton-85 in the atmosphere according to claim 1, characterized in that, The adjustment assembly includes a drive assembly and a stage. The drive assembly is used to move the activated carbon adsorption trap on the stage to fit or separate from the cold head of the refrigerator.

5. The high and low temperature control device for temperature-variable adsorption and separation of krypton-85 in the atmosphere according to claim 4, characterized in that, The stage is horizontally positioned inside the vacuum chamber. The cold head of the refrigerator extends into the vacuum chamber from the upper end. The drive assembly drives the upper end of the activated carbon adsorption trap on the stage to move vertically and either come into contact with or separate from the cold head of the refrigerator.

6. The high and low temperature control device for temperature-variable adsorption and separation of krypton-85 in the atmosphere according to claim 1, characterized in that, The activated carbon adsorption trap and the heating element are bonded and fixed together with thermally conductive adhesive.

7. The high and low temperature control device for temperature-variable adsorption and separation of krypton-85 in the atmosphere according to claim 1, characterized in that, It also includes a temperature sensor disposed on the activated carbon adsorption trap.

8. The high and low temperature control device for temperature-variable adsorption and separation of krypton-85 in the atmosphere according to claim 1, characterized in that, The inner wall of the vacuum chamber is provided with a heat insulation layer, and a vacuum gauge is installed on the vacuum chamber to detect the vacuum level inside the vacuum chamber in real time.

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