A non-powered temperature-adjustable cold trap

Abstract

The present invention discloses an unpowered adjustable temperature cold trap, which belongs to the technical field of cooling devices and solves the problem that the existing liquid nitrogen cold trap cannot accurately and continuously adjust the freezing temperature according to the experimental needs. The unpowered adjustable temperature cold trap includes: a first freezing space, which is configured to accommodate a first freezing medium; a second freezing space, which is placed in the first freezing space and is configured to accommodate a second freezing medium, and the temperature of the second freezing medium is higher than that of the first freezing medium; the second freezing space has a first inlet and a first outlet, the first inlet is for the second freezing medium to flow in, and the first outlet is for the second freezing medium to flow out; a third freezing space is placed in the second freezing space, and the third freezing space has a second inlet and a second outlet, the second inlet is for the mixed gas containing the target gas to flow in, and the second outlet is connected to the downstream test gas path. The present invention realizes the accurate and continuous adjustment of the freezing temperature of the cold trap.

Description

Technical Field

[0001] The present application belongs to the technical field of cooling devices, and in particular relates to a non-powered temperature-adjustable cold trap. Background Art

[0002] A cold trap is a cooling device used to collect gases within a certain melting point range. Common cold traps use a U-shaped tube, which is directly placed in a container containing a refrigerant. When the mixed gas passes through the U-shaped tube, the gas with a high melting point becomes solid, and the gas with a low melting point passes through the U-shaped tube, which plays a role in gas separation. When the frozen solid needs to be turned into a gas, the U-shaped tube needs to be removed from the refrigerant to achieve sublimation of the solid to gas at a natural temperature, or the U-shaped tube needs to be heated by a heating device to accelerate the sublimation process.

[0003] However, since the freezing temperature of the liquid cryogen is fixed, such as the freezing temperature of pure liquid nitrogen cryogen in the prior art is -196°C, and the freezing temperature range of liquid nitrogen and ethanol mixed cryogens in different proportions is -120°C to -60°C, the freezing environment temperature of the U-shaped tube is also fixed, which cannot meet the freezing needs between -196°C and -120°C. At the same time, during the test process, the freezing temperature cannot be accurately and continuously adjusted according to the experimental needs, and it is difficult to separate different gases with similar melting points. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a non-powered temperature-adjustable cold trap to solve the above technical problems existing in the prior art.

[0005] The object of the present invention is achieved in that:

[0006] A non-powered temperature-adjustable cold trap, comprising:

[0007] a first freezing space configured to contain a first freezing medium;

[0008] A second freezing space is disposed in the first freezing space and is configured to contain a second freezing medium, wherein the temperature of the second freezing medium is higher than that of the first freezing medium; the second freezing space has a first inlet and a first outlet, wherein the first inlet is for the second freezing medium to flow in, and the first outlet is for the second freezing medium to flow out;

[0009] The third freezing space is disposed in the second freezing space. The third freezing space has a second inlet and a second outlet. The second inlet is for the mixed gas containing the target gas to flow in. The second outlet is connected to the downstream test gas path.

[0010] Furthermore, the second freezing space and the third freezing space have the same shape, and their axes coincide with each other.

[0011] Furthermore, the second freezing space and the third freezing space are both U-shaped spaces.

[0012] Furthermore, the first freezing medium is liquid nitrogen, and the second freezing medium is nitrogen at room temperature.

[0013] Furthermore, it comprises a liquid nitrogen barrel and an outer tube and an inner tube, wherein the accommodation space in the liquid nitrogen barrel is a first freezing space, the inner space of the outer tube is a second freezing space, and the inner space of the inner tube is a third freezing space.

[0014] Furthermore, a sealed space is formed between the inner wall of the outer tube and the outer wall of the inner tube, and the two end openings of the inner tube extend out of the two end openings of the outer tube; wherein the first inlet and the first outlet are arranged on the side wall of the outer tube and are connected to the sealed space; and the second inlet and the second outlet are located at the two end openings of the inner tube.

[0015] Furthermore, it also includes a nitrogen source, which is connected to the first inlet of the second freezing space through a gas supply pipe.

[0016] Furthermore, a flow valve is provided on the air supply pipe.

[0017] Further, at least a portion of the air supply pipe is located in the first freezing medium of the first freezing space.

[0018] Furthermore, the diameter of the outer tube is 20-40 mm, the diameter of the inner tube is 5-7 mm, and the diameter of the air supply tube is 2-3 mm.

[0019] Furthermore, the temperature adjustment range in the third freezing space is -90°C to -160°C.

[0020] Furthermore, there are multiple second freezing spaces, which are arranged layer by layer from the inside to the outside, and an annular ventilation space is formed between two adjacent second freezing spaces. Each annular ventilation space is provided with a first inlet and a first outlet.

[0021] Furthermore, the first inlet of each annular ventilation space is connected to the air supply pipe through a branch air pipe, and each of the branch air pipes is provided with a branch flow valve.

[0022] Furthermore, from outside to inside, the distance between the inner walls of two adjacent second freezing spaces decreases successively.

[0023] Furthermore, a temperature sensor is provided on the outer wall of the inner tube for real-time monitoring of the temperature inside the inner tube.

[0024] Furthermore, it also includes a nitrogen collecting device, which has a gas collecting space and a gas collecting port and an exhaust port connected to the gas collecting space; the gas collecting space is provided with a temperature sensor, the gas collecting port is connected to the first outlet of the outer tube, and the exhaust port is connected to the nitrogen source through a nitrogen replenishment path, so as to replenish the nitrogen in the gas collecting space to room temperature into the nitrogen source.

[0025] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0026] a) The non-powered adjustable temperature cold trap provided by the present invention, by placing the third freezing space in the second freezing space, uses the first freezing medium in the first freezing space to freeze the second freezing medium flowing in the second freezing space, thereby realizing indirect freezing of the third freezing space by the first freezing medium. At the same time, since the second freezing medium in the second space is flowing, the freezing temperature in the second freezing space can be accurately and continuously adjusted by adjusting the nitrogen flow rate, flow rate and nitrogen temperature supplied to the second freezing space, and no additional thermal power is required during the adjustment process.

[0027] b) The non-powered adjustable temperature cold trap provided by the present invention comprises a liquid nitrogen barrel and an outer tube and an inner tube, a sealed space is formed between the inner tube and the outer tube, the liquid nitrogen in the liquid nitrogen barrel directly cools the nitrogen in the gas supply pipe and the sealed space, and the low-temperature nitrogen in the annular space freezes the mixed gas in the inner tube. The non-powered adjustable temperature cold trap has a simple structure, is easy to operate, has a low cost, and can be unattended. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this specification. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0029] Figure 1 A schematic diagram of the structure of the non-powered temperature-adjustable cold trap provided by the present invention;

[0030] Figure 2 A schematic diagram of the structural arrangement of the inner tube and the outer tube of the unpowered temperature-adjustable cold trap provided by the present invention.

[0031] Reference numerals:

[0032] 1-liquid nitrogen barrel; 2-outer tube; 21-nitrogen inlet; 22-nitrogen outlet; 3-inner tube; 31-air inlet; 32-air outlet; 4-sealed space; 5-air supply pipe; 6-nitrogen source; 7-flow valve. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] To facilitate understanding of the embodiments of the present application, further explanation will be given below with reference to specific embodiments in conjunction with the accompanying drawings. The embodiments do not constitute a limitation on the embodiments of the present application.

[0035] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connected" should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or an integral connection can be a mechanical connection, or an electrical connection, can be a direct connection, or can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] The terms "top", "bottom", "above", "lower", and "on" used throughout the description are relative to the relative positions of components of a device, such as the relative positions of the top and bottom substrates within a device. It is understood that devices are multifunctional regardless of their orientation in space.

[0037] Example 1

[0038] A specific embodiment of the present invention, as Figure 1 to Figure 2 As shown, a non-powered temperature-adjustable cold trap is disclosed, comprising:

[0039] a first freezing space configured to contain a first freezing medium;

[0040] A second freezing space is disposed in the first freezing space and is configured to contain a second freezing medium, wherein the temperature of the second freezing medium is higher than that of the first freezing medium; the second freezing space has a first inlet and a first outlet, wherein the first inlet is for the second freezing medium to flow in, and the first outlet is for the second freezing medium to flow out;

[0041] The third freezing space is placed in the second freezing space, and the third freezing space has a second inlet and a second outlet. The second inlet is for the mixed gas containing the target gas to flow in, and the second outlet is connected to the downstream test gas circuit. The unfrozen gas flows out from the second outlet, and the gas sublimated by the frozen solid when heated flows out from the second outlet.

[0042] In one optional embodiment, the first freezing medium is liquid nitrogen, and the temperature of the liquid nitrogen is -196°C; the second freezing medium is nitrogen gas.

[0043] In this embodiment, the unpowered adjustable temperature cold trap further includes a nitrogen source 6, which is connected to the first inlet of the second freezing space through a gas supply pipe 5. Optionally, the nitrogen provided by the nitrogen source 6 is at room temperature, and when in use, the coiled part of the nitrogen gas supply pipeline 5 is placed in the first freezing medium to cool the room temperature nitrogen, thereby enabling accurate and continuous adjustment of the freezing temperature in the second freezing space without the need for additional thermal power.

[0044] In one of the optional embodiments, a flow valve 7 is provided on the air supply pipe 5, and the flow rate and flow velocity of nitrogen in the air supply pipe 5 can be controlled by the flow valve 7 according to the diameters of the inner tube 3 and the outer tube 2, and the temperature of the nitrogen in the air supply pipe 5 can be controlled at the same time, so as to achieve accurate, continuous and dynamic adjustment of the freezing temperature in the second freezing space, that is, to adjust the temperature in the third freezing space, and the temperature adjustment range is -90°C to -160°C, and the adjustment accuracy is not higher than 1°C, so as to meet the purpose of precise temperature control.

[0045] In one of the optional embodiments, at least a portion of the gas supply pipe 5 is located in the first freezing medium of the first freezing space. For example, the gas supply pipe 5, which is at least about 60 cm long, is immersed in a -196°C liquid nitrogen barrel, and the gas supply pipe 5 is in contact with liquid nitrogen for refrigeration. The nitrogen gas with reduced temperature is supplied into the sealed space 4 between the outer tube 2 and the inner tube 3 through the nitrogen inlet 21, and flows out from the nitrogen outlet 22. The first freezing medium of the first freezing space and the supplied low-temperature nitrogen gas jointly cool the inner tube 3, thereby freezing the target gas in the inner tube 3. In this process, the supplied nitrogen gas plays a heating role. By immersing part of the nitrogen gas supply pipe in liquid nitrogen to reduce the heating rate, the freezing temperature is made more stable. In this embodiment, by placing a portion of the gas supply pipe 5 in the first freezing medium, the first freezing medium is used to cool the nitrogen gas flowing in the gas supply pipe 5, the temperature difference between the nitrogen temperature and the set target temperature is reduced, and the low temperature of the third freezing space is made more stable. At the same time, the freezing temperature can be accurately adjusted by adjusting the nitrogen gas flow rate and flow rate supplied.

[0046] Furthermore, the air supply pipe 5 is a hose, and the air supply pipe 5 is coiled in the first freezing space, and the coiled part is located in the first freezing medium. By coiling most of the air supply pipe 5 and placing it in the first freezing medium, the cooling time of the nitrogen in the air supply pipe 5 can be extended, ensuring that the temperature of the nitrogen supplied to the second freezing space reaches a lower target temperature, and the temperature of the low-temperature nitrogen supplied can also be kept consistent.

[0047] In one optional embodiment, the second freezing space is the same shape as the third freezing space, and the axes of the two coincide. Exemplarily, the second freezing space and the third freezing space are both U-shaped spaces. This structural setting enables the third freezing space to be located at the center of the second freezing space, and the second freezing medium around the third freezing space is evenly distributed, ensuring that the freezing effect at different positions of the third freezing space is the same, which helps to improve the control accuracy of the cold trap temperature.

[0048] In this embodiment, the unpowered adjustable temperature cold trap includes a liquid nitrogen barrel 1 and an outer tube 2 and an inner tube 3; wherein the accommodating space in the liquid nitrogen barrel 1 is a first freezing space, the inner space of the outer tube 2 is a second freezing space, and the inner space of the inner tube 3 is a third freezing space.

[0049] Specifically, if Figure 2 As shown, the outer tube 2 and the inner tube 3 are both U-shaped tubes, a sealed space 4 is formed between the inner wall of the outer tube 2 and the outer wall of the inner tube 3, the tube mouth of the outer tube 2 is sealed and connected to the outer wall of the inner tube 3, and the two end tube mouths of the inner tube 3 extend out of the two end tube mouths of the outer tube 2; wherein, the first inlet and the first outlet are arranged on the side wall of the outer tube 2 and are connected to the sealed space 4, the first inlet is a nitrogen inlet 21, and the first outlet is a nitrogen outlet 22; the second inlet and the second outlet are located at the two end tube mouths of the inner tube 3, one end of the inner tube 3 is an air inlet 31, and the other end is an air outlet 32, that is, the second inlet is an air inlet 31, and the second outlet is an air outlet 32.

[0050] In this embodiment, the diameter of the outer tube 2 is 20-40 mm, the diameter of the inner tube 3 is 5-7 mm, and the diameter of the air supply tube 5 is 2-3 mm. For example, the diameter of the inner tube 3 is 6.35 mm, and the diameter of the air supply tube 5 is 1.6 mm.

[0051] In one optional embodiment, the number of the second freezing spaces is multiple, and the multiple second freezing spaces are arranged layer by layer from the inside to the outside, and an annular ventilation space is formed between two adjacent second freezing spaces, and each annular ventilation space is provided with a first inlet and a first outlet, that is, each annular ventilation space is provided with a nitrogen inlet 21 and a nitrogen outlet 22, and each annular ventilation space is independently introduced with nitrogen, and the nitrogen flow rate supplied to each annular ventilation space can be set differently. Further, the first inlet of each annular ventilation space is connected to the air supply pipe 5 through a branch air pipe, and each of the branch air pipes is provided with a branch flow valve. By setting up multiple independently arranged second freezing spaces, by controlling the nitrogen flow rate, flow rate and nitrogen temperature in different second freezing spaces, multi-stage and step-by-step temperature control can be achieved, so that the cooling temperature of the second freezing space can be more accurately and continuously adjusted and controlled.

[0052] In one of the optional embodiments, the volumes of the multiple annular ventilation spaces are different, and each annular ventilation space is independent and not connected to each other. From the outside to the inside, the distance between the inner walls of two adjacent second freezing spaces decreases successively. By setting the volumes of the multiple annular ventilation spaces differently, and increasing the distance between the inner walls of the annular ventilation spaces successively from the inside to the outside, the annular ventilation space closer to the third freezing space is narrower, and is more sensitive to the nitrogen temperature, flow rate, and flow rate inside it. Therefore, the nitrogen temperature, flow rate, and flow rate in the annular ventilation space can be adjusted successively from the outside to the inside, so as to improve the precise regulation of the freezing temperature in the third freezing space and further improve the temperature control accuracy.

[0053] In one of the optional implementations, a first temperature sensor is provided on the outer wall of the inner tube 3 for monitoring the temperature inside the inner tube 3 in real time.

[0054] In one optional embodiment, the unpowered adjustable temperature cold trap further includes a nitrogen collection device, which has a gas collection space and a gas collection port and an exhaust port connected to the gas collection space; the gas collection space is provided with a second temperature sensor, the gas collection port is connected to the first outlet of the outer tube 2, and the exhaust port is connected to the nitrogen source 6 through a nitrogen replenishment path, so as to replenish the nitrogen in the gas collection space that has been restored to room temperature into the nitrogen source 6. This structural setting can realize the recycling of nitrogen, which is helpful to achieve unattended operation.

[0055] In one of the optional embodiments, the unpowered adjustable temperature cold trap includes multiple cold trap units, each cold trap unit includes an outer tube 2 and an inner tube 3, at least two cold trap units are connected in series to the test gas circuit, and in two adjacent cold trap units, the inner tube air outlet of one cold trap unit is connected to the inner tube air inlet of another cold trap unit through an air circuit, and the outer tube nitrogen inlet of each cold trap unit is connected to the nitrogen source 6 through an independent air circuit. Exemplarily, the unpowered adjustable temperature cold trap includes a first cold trap unit and a second cold trap unit connected in the direction of air flow, the first cold trap unit includes a first outer tube and a first inner tube, the first outer tube has a first nitrogen inlet and a first nitrogen outlet, the first inner tube has a first air inlet and a first air outlet; the second cold trap unit includes a second outer tube and a second inner tube, the second outer tube has a second nitrogen inlet and a second nitrogen outlet, the second inner tube has a second air inlet and a second air outlet; wherein, the first nitrogen inlet is connected to the air supply pipe 5 through a first sub-air path, and a first flow valve is provided on the first sub-air path; the second nitrogen inlet is connected to the air supply pipe 5 through a second sub-air path, and a second flow valve is provided on the second sub-air path; the first air inlet is connected to the air outlet of the target gas production device, the first air outlet is connected to the second air inlet of the second inner tube through an air guide tube, and the second air outlet of the second inner tube is connected to the downstream test air path. By setting up multiple cold trap units in series, the nitrogen flow, flow rate and temperature of each unit are independently controlled. Therefore, not only can the target gas be frozen and enriched twice, but also two cold trap temperatures can be set as needed to achieve the sequential separation of different types of target gases in one cold trap gas path.

[0056] During implementation, nitrogen of a certain temperature is supplied from the nitrogen inlet 21 to the sealed space 4 between the outer tube 2 and the inner tube 3 by the nitrogen source 6. Since a part of the gas supply pipe 5 is located in liquid nitrogen, the nitrogen is cooled by the liquid nitrogen before being supplied to the sealed space 4. The nitrogen flow rate in the gas supply pipe 5 is controlled by adjusting the flow valve 7. In combination with the temperature of the supplied nitrogen, the nitrogen supplied to the sealed annular space 4 can maintain a specific temperature, thereby forming a freezing environment for the inner tube 3. The mixed gas containing the target gas enters the inner tube 3 from the gas inlet 31. Since the inner tube 3 is in the low temperature environment of the sealed space 4, the target gas is frozen at the bottom of the inner tube 3 during the mixed gas flowing through the inner tube 3, and the remaining non-target gas flows out from the gas outlet 32. When it is necessary to sublimate the solid substance into a gaseous state, the outer tube 2, the inner tube 3 and the gas supply pipe 5 are taken out of the liquid nitrogen barrel, placed in the air, and sublimated into a gaseous state at room temperature, or the nitrogen flow rate in the gas supply pipe 5 is increased by the flow valve 7 to increase the temperature of the cold trap to sublimate it into a gaseous state.

[0057] Compared with the prior art, the unpowered temperature-adjustable cold trap provided in this embodiment has at least one of the following beneficial effects:

[0058] 1. By placing the third freezing space in the second freezing space, the first freezing medium in the first freezing space is used to freeze the second freezing medium flowing in the second freezing space, thereby realizing indirect freezing of the third freezing space by the first freezing medium. At the same time, since the second freezing medium in the second space is flowing, the freezing temperature in the second freezing space can be accurately and continuously adjusted by adjusting the nitrogen flow rate, flow rate and nitrogen temperature supplied to the second freezing space.

[0059] 2. The unpowered adjustable temperature cold trap includes a liquid nitrogen barrel and an outer tube and an inner tube. A sealed space is formed between the inner tube and the outer tube. The liquid nitrogen in the liquid nitrogen barrel directly cools the nitrogen in the gas supply pipe and the sealed space, and the low-temperature nitrogen in the annular space freezes the mixed gas in the inner tube. The unpowered adjustable temperature cold trap has a simple structure, is easy to operate, has a low cost, and can be unattended.

[0060] 3. By setting up multiple independently arranged second freezing spaces and controlling the nitrogen flow rate, flow rate and nitrogen temperature in different second freezing spaces, multi-stage and step-by-step temperature control can be achieved, so that the cooling temperature of the second freezing space can be adjusted and controlled more accurately and continuously.

[0061] 4. By setting the volumes of multiple annular ventilation spaces differently and increasing the distance between the inner walls of the annular ventilation spaces from the inside to the outside, the annular ventilation space closer to the third freezing space is narrower and more sensitive to the nitrogen temperature, flow rate and flow rate inside it. Therefore, the nitrogen temperature, flow rate and flow rate in the annular ventilation space can be adjusted from the outside to the inside, thereby improving the precise adjustment of the freezing temperature in the third freezing space and further improving the temperature control accuracy.

[0062] 5. By setting up multiple cold trap units in series, the nitrogen flow, flow rate and temperature of each unit are independently controlled, which can not only freeze and enrich the target gas multiple times, but also set two cold trap temperatures as needed to achieve the sequential separation of different types of target gases in one cold trap gas path.

[0063] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation method of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A non-powered temperature-adjustable cold trap, characterized in that: include: a first freezing space configured to contain a first freezing medium; A second freezing space is disposed in the first freezing space and is configured to contain a second freezing medium, wherein the temperature of the second freezing medium is higher than that of the first freezing medium; the second freezing space has a first inlet and a first outlet, wherein the first inlet is for the second freezing medium to flow in, and the first outlet is for the second freezing medium to flow out; A third freezing space is disposed in the second freezing space, the third freezing space having a second inlet and a second outlet, the second inlet is for a mixed gas containing a target gas to flow in, and the second outlet is connected to a downstream test gas path; a nitrogen source (6), the nitrogen source (6) being connected to the first inlet of the second freezing space via a gas supply pipe (5); At least a portion of the air supply pipe (5) is located in the first freezing medium of the first freezing space.

2. The unpowered temperature-adjustable cold trap according to claim 1, characterized in that: The second freezing space and the third freezing space have the same shape, and their axes coincide with each other.

3. The unpowered temperature-adjustable cold trap according to claim 2, characterized in that: The second freezing space and the third freezing space are both U-shaped spaces.

4. The unpowered temperature-adjustable cold trap according to any one of claims 1 to 3, characterized in that: The first freezing medium is liquid nitrogen, and the second freezing medium is nitrogen at room temperature.

5. The unpowered temperature-adjustable cold trap according to claim 4, characterized in that: The invention comprises a liquid nitrogen barrel (1) and a sleeved outer tube (2) and an inner tube (3), wherein the accommodating space in the liquid nitrogen barrel (1) is a first freezing space, the inner space of the outer tube (2) is a second freezing space, and the inner space of the inner tube (3) is a third freezing space.

6. The unpowered temperature-adjustable cold trap according to claim 5, characterized in that: A sealed space (4) is formed between the inner wall of the outer tube (2) and the outer wall of the inner tube (3), and the two end openings of the inner tube (3) extend out of the two end openings of the outer tube (2); Wherein, the first inlet and the first outlet are arranged on the side wall of the outer tube (2) and are connected to the sealed space (4); The second inlet and the second outlet are located at the two end openings of the inner tube (3).

7. The unpowered temperature-adjustable cold trap according to claim 1, characterized in that: The air supply pipe (5) is provided with a flow valve (7).

8. The unpowered temperature-adjustable cold trap according to claim 5, characterized in that: The diameter of the outer tube (2) is 20-40 mm, the diameter of the inner tube (3) is 5-7 mm, and the diameter of the air supply tube (5) is 2-3 mm; The temperature adjustment range in the third freezing space is -90°C to -160°C.

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