A rectification system and method for producing boron isotopes
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI ZHENGFAN TECH
- Filing Date
- 2025-04-10
- Publication Date
- 2026-08-07
AI Technical Summary
[0004]本申请的目的在于提供一种生产硼同位素的精馏系统以及方法，该精馏系统能够解决精馏塔在制备硼同位素的过程中容易因BF3“结冰”导致无法正常运行的问题
[0033]上述技术方案中，将压缩机的压缩比限定在上述范围，以使得氮气达到再沸器时温度维持在-55~-95℃的范围内，从而便于和液态的三氟化硼进行热交换并使其气化。
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Figure CN120132390B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of boron isotope preparation technology, and more specifically, to a distillation system and method for producing boron isotopes. Background Technology
[0002] Currently, existing methods for boron isotope separation and enrichment include cryogenic distillation, chemical exchange distillation, ion exchange chromatography, laser distillation, and centrifugation. Industrial applications primarily focus on chemical exchange distillation and cryogenic distillation. Among these, the mainstream technology in chemical exchange distillation is the anisole complex exchange method. This method has a complex process, high operational requirements, and the presence of moisture during distillation is difficult to avoid, with the generated byproduct (HF) being highly corrosive. In contrast, cryogenic distillation mainly employs BF3 distillation. Since F has only one stable isotope and B has only two stable isotopes, only [the remaining isotope] is present during the entire separation process. 11 BF3 and 10 BF3 contains two substances (specifically, collected at the bottom). 10 BF3, Top Collection 11 BF3 has a relatively simple composition, and no chemical changes or byproducts are generated during the separation process, resulting in products with fewer impurities and higher purity. Furthermore, low-temperature distillation is easy to scale up. Therefore, low-temperature distillation is expected to become the most ideal preparation process for the industrial production of boron isotopes in the future.
[0003] However, in the process of preparing boron isotopes using cryogenic distillation, the separation coefficient is only 1.0075, and reflux condensation must be carried out between the melting point (-127℃) and normal boiling point (-101℃) of BF3. Currently, liquid nitrogen is commonly used as a refrigerant; however, the temperature of liquid nitrogen is usually -198℃, which can easily cause BF3 to "freeze" inside the distillation column during the preparation process (i.e., gaseous BF3 turns into a solid after cooling), thus making it difficult for the distillation column to operate normally. Summary of the Invention
[0004] The purpose of this application is to provide a distillation system and method for producing boron isotopes, which can solve the problem that the distillation column is prone to malfunction due to BF3 "icing" during the preparation of boron isotopes.
[0005] The embodiments of this application are implemented as follows: In a first aspect, embodiments of this application provide a distillation system for producing boron isotopes, including a distillation column and a condensation device. The distillation column includes a column body, a BF3 condenser located at the top of the column body, and a reboiler located at the bottom of the column body. The condensation device includes a liquid nitrogen storage tank and an intermediate condenser. The liquid nitrogen storage tank is connected to a liquid nitrogen source, and the intermediate condenser is connected to a gaseous medium source. The intermediate condenser has a first heat exchange zone and a second heat exchange zone, which are connected. The first heat exchange zone is configured to exchange heat with the liquid nitrogen provided by the liquid nitrogen storage tank, such that the gaseous medium located in the first heat exchange zone is at least partially cooled and liquefied after heat exchange to obtain a liquid medium, which is then collected in the second heat exchange zone. The second heat exchange zone is configured to exchange heat with the gaseous BF3 in the BF3 condenser using the liquid medium, such that the liquid medium provided by the second heat exchange zone is heated and vaporized after heat exchange and returns to the first heat exchange zone.
[0006] In the above technical solution, a condensation device is added to the conventional distillation column in the distillation system. Specifically, the condensation device includes a liquid nitrogen storage tank and an intermediate condenser. The liquid nitrogen storage tank is connected to a liquid nitrogen source, and the intermediate condenser is connected to a gaseous medium source. The intermediate condenser has a first heat exchange zone and a second heat exchange zone connected in series. The first heat exchange zone is configured to exchange heat with the liquid nitrogen provided by the liquid nitrogen storage tank, so that the gaseous medium located in the first heat exchange zone is at least partially cooled and liquefied after heat exchange to obtain a liquid medium, which then collects in the second heat exchange zone. The second heat exchange zone is configured to utilize... The liquid medium exchanges heat with the gaseous BF3 in the BF3 condenser, causing the liquid medium provided by the second heat exchange zone to heat up and vaporize after the heat exchange and return to the first heat exchange zone. By adding an intermediate condenser, that is, using the heat exchange medium in the intermediate condenser as an intermediate bridge, the heat exchange medium that exchanges heat with the gaseous BF3 in the BF3 condenser is not liquid nitrogen but a liquid medium with a temperature higher than liquid nitrogen (obtained by liquefaction of the gaseous medium after heat exchange with liquid nitrogen). This solves the problem that the distillation column is prone to malfunction due to BF3 "icing" during the preparation of boron isotopes.
[0007] In some alternative implementations, along the height of the tower, from top to bottom, the liquid nitrogen storage tank, the intermediate condenser, and the BF3 condenser are connected in sequence, wherein the first heat exchange zone is located at the top of the intermediate condenser, the second heat exchange zone is located at the bottom of the intermediate condenser, the liquid nitrogen storage tank is connected to the first heat exchange zone, and the BF3 condenser is connected to the second heat exchange zone.
[0008] In the above technical solution, the liquid nitrogen storage tank, intermediate condenser and BF3 condenser are connected sequentially from top to bottom, that is, the three are set up as a whole, which has the advantages of a more compact overall structure and less space occupation.
[0009] In some alternative implementations, the liquid nitrogen storage tank is fitted within the first heat exchange zone, and the second heat exchange zone is fitted within the BF3 condenser. The liquid nitrogen storage tank and the first heat exchange zone, as well as the second heat exchange zone and the BF3 condenser, are connected by corresponding connection surfaces as heat exchange sites.
[0010] In some alternative implementations, the first heat exchange zone is fitted onto the liquid nitrogen storage tank, and the BF3 condenser is fitted onto the second heat exchange zone. The liquid nitrogen storage tank and the first heat exchange zone, as well as the second heat exchange zone and the BF3 condenser, are connected by corresponding surfaces as heat exchange sites.
[0011] In the above technical solution, the liquid nitrogen storage tank, intermediate condenser and BF3 condenser are nested in sequence with the connection surface as the heat exchange site, which has the advantages of compact overall structure, reasonable layout, high connection stability and high heat exchange efficiency. At the same time, this arrangement can also make it easier for the heat exchange medium contained in the intermediate condenser to self-circulate, that is, the gaseous medium at the top cools down and turns into liquid medium and collects at the bottom, and the liquid medium at the bottom heats up and turns into gaseous medium and returns to the top.
[0012] In some alternative implementations, the liquid nitrogen storage tank is also equipped with a pressure detection unit and / or a temperature detection unit.
[0013] In the above technical solution, after heat exchange, the pressure and temperature inside the liquid nitrogen storage tank will rise. The liquid nitrogen storage tank is equipped with a pressure detection unit and / or a temperature detection unit to realize real-time monitoring of the state inside the liquid nitrogen storage tank, so as to facilitate the determination of whether new liquid nitrogen needs to be added based on the pressure and temperature indicators.
[0014] In some alternative implementations, along the height of the tower body from top to bottom, the intermediate condenser includes a first heat exchange zone and a second heat exchange zone, and a feed zone located between them, the inner diameter of the feed zone being smaller than the inner diameter of the first heat exchange zone and the inner diameter of the second heat exchange zone.
[0015] In the above technical solution, the material conveying zone in the intermediate condenser does not participate in heat exchange. It is set to have an inner diameter smaller than that of the first and second heat exchange zones at both ends, that is, the whole is in the form of being small in the middle and large at both ends. This can reduce manufacturing materials and reduce manufacturing costs. At the same time, it also makes the intermediate condenser have a high heat exchange efficiency.
[0016] In some alternative implementations, along the height direction of the tower body, the conveying zone includes a buffer section and equal-diameter conveying sections located at both ends of the buffer section, and the inner diameter of the buffer section is larger than the inner diameter of the equal-diameter conveying sections. The equal-diameter conveying section at the upper end is connected to the first heat exchange zone, and the equal-diameter conveying section at the lower end is connected to the second heat exchange zone.
[0017] In the above technical solution, the conveying zone is set up in the form of a buffer section and a constant diameter conveying section. The inner diameter of the buffer section is larger than that of the constant diameter conveying section. That is, the conveying zone is generally large in the middle and small at both ends. The buffer section can temporarily store a part of the liquid medium, which can better maintain the temperature stability of the distillation column when the liquid nitrogen is insufficient.
[0018] In some alternative implementations, the nitrogen outlet of the liquid nitrogen storage tank is connected to the heat exchange medium inlet of the reboiler via a compressor.
[0019] In the above technical solution, the nitrogen outlet of the liquid nitrogen storage tank is connected to the heat exchange medium inlet of the reboiler, that is, the nitrogen generated after the liquid nitrogen heat exchange is used as the heat source of the reboiler to realize the secondary utilization of nitrogen and save manufacturing costs. At the same time, the nitrogen outlet of the liquid nitrogen storage tank and the heat exchange medium inlet of the reboiler are connected through a compressor, which facilitates the adjustment of the nitrogen temperature so that the nitrogen has a more suitable temperature after arriving at the reboiler, thereby better heating the liquid boron trifluoride and vaporizing it.
[0020] In some alternative implementations, the liquid nitrogen storage tank, the intermediate condenser, and the BF3 condenser are spaced apart. The internal cavity of the intermediate condenser is used to communicate with a gaseous medium source. A first heat exchange zone is located at the top of the intermediate condenser, and a second heat exchange zone is located at the bottom of the intermediate condenser. The side wall of the cavity corresponding to the first heat exchange zone has a first fluid channel that can exchange heat with the cavity. The first fluid channel is connected to the liquid nitrogen storage tank to allow liquid nitrogen to be introduced into the first fluid channel, so that the gaseous medium in the first heat exchange zone is at least partially cooled and liquefied after heat exchange and collects in the second heat exchange zone. The side wall of the cavity corresponding to the second heat exchange zone has a second fluid channel, which is configured to transport the liquid medium to the BF3 condenser for heat exchange with the gaseous BF3 in the BF3 condenser, and also to allow the liquid medium to heat up and vaporize after heat exchange and return to the first heat exchange zone.
[0021] In the above technical solution, the liquid nitrogen storage tank, intermediate condenser and BF3 condenser are all distributed at intervals, that is, set in a separate form and connected by pipelines for heat exchange, which facilitates the assembly and layout of the distillation system when there is not enough vertical space.
[0022] Secondly, embodiments of this application provide a method for producing boron isotopes, using a distillation system as provided in the first aspect embodiment, comprising the following steps: The raw material is fed into the column for distillation. First, liquid nitrogen from the liquid nitrogen storage tank is used to exchange heat with the gaseous medium in the first heat exchange zone. After the heat exchange, the gaseous medium in the first heat exchange zone is at least partially cooled and liquefied to obtain a liquid medium, which is then collected in the second heat exchange zone. The liquefaction temperature of the gaseous medium is -100 to -120°C. Then, the liquid medium in the second heat exchange zone is used to exchange heat with the gaseous BF3 in the BF3 condenser. After the heat exchange, the liquid medium provided by the second heat exchange zone is heated and vaporized, and then returns to the first heat exchange zone.
[0023] In the above technical solution, the method for producing boron isotopes uses a distillation system as provided in the first aspect embodiment. Since it adds an intermediate condenser to the conventional distillation column, and the liquefaction temperature of the heat exchange medium in the intermediate condenser is -100~-120℃, the overall heat exchange process is as follows: liquid nitrogen first exchanges heat with the gaseous medium to cool the gaseous medium and liquefy it into a liquid medium with a temperature close to -100℃. Then, the liquid medium exchanges heat with the gaseous BF3 in the BF3 condenser. This ensures that the heat exchange medium exchanging heat with the gaseous BF3 in the BF3 condenser is not liquid nitrogen but a liquid medium with a temperature of around -100℃, thereby solving the problem of "icing" inside the distillation column caused by liquid nitrogen directly exchanging heat with the gaseous BF3 in the BF3 condenser.
[0024] In some alternative embodiments, the gaseous medium includes a heat exchange gaseous medium and a buffer gaseous medium, wherein the volume ratio of the buffer gaseous medium is greater than that of the heat exchange gaseous medium, wherein the heat exchange gaseous medium is selected from at least one of nitrogen trifluoride, carbon tetrafluoride, methane, ethylene and oxygen, and the buffer gaseous medium is selected from at least one of hydrogen, neon and helium.
[0025] In the above technical solution, the gaseous medium is composed of the above-mentioned heat exchange gaseous medium and buffer gaseous medium, and the volume ratio of the buffer gaseous medium is greater than that of the heat exchange gaseous medium. This makes the overall pressure change of the gaseous medium smaller during liquefaction and vaporization (pressure change will cause temperature change), thereby keeping the temperature of the first heat exchange zone and the second heat exchange zone of the intermediate condenser within a suitable range, which helps to improve the stability of the distillation system.
[0026] In some alternative implementations, the pressure inside the intermediate condenser is 1 to 50 bar after the heat exchange gaseous medium in the intermediate condenser is liquefied.
[0027] Optionally, the heat exchange gaseous medium is oxygen, and after the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure inside the intermediate condenser is 5~10 bar.
[0028] Optionally, the heat exchange gaseous medium is ethylene, and after the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure inside the intermediate condenser is 1~2 bar.
[0029] Optionally, the heat exchange gaseous medium is nitrogen trifluoride and / or carbon tetrafluoride, and the pressure inside the intermediate condenser is 2~6 bar after the heat exchange gaseous medium in the intermediate condenser is liquefied.
[0030] Optionally, the heat exchange gaseous medium is methane, and after the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure in the intermediate condenser is 15~30 bar.
[0031] In the above technical solution, after the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure inside the intermediate condenser is controlled within the above range so that the temperature of the liquid medium is closer to -100℃, thereby more accurately controlling the temperature of the distillation column at a suitable separation temperature; furthermore, for different types of heat exchange gaseous medium, the pressure of the gaseous medium after liquefaction is limited within the above range, which can make the temperature of the liquid medium even closer to -100℃.
[0032] In some alternative implementations, the nitrogen outlet of the liquid nitrogen storage tank is connected to the heat exchange medium inlet of the reboiler via a compressor, and the compressor has a compression ratio of 2 to 20.
[0033] In the above technical solution, the compression ratio of the compressor is limited to the above range so that the temperature of the nitrogen gas is maintained in the range of -55~-95℃ when it reaches the reboiler, thereby facilitating heat exchange with liquid boron trifluoride and causing it to vaporize. Attached Figure Description
[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0035] Figure 1 This is a schematic diagram of the structure of the first distillation system provided in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of a second distillation system provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a first type of intermediate condenser provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a second type of intermediate condenser provided in an embodiment of this application; Figure 5This is a schematic diagram of the structure of the third distillation system provided in the embodiments of this application; Figure 6 This is a schematic diagram of the structure of the fourth distillation system provided in the embodiments of this application.
[0036] Icons: 10-Distillation system; 100-Distillation column; 110-Column body; 120-BF3 condenser; 130-Reboiler; 140-Insulating diaphragm; 200-Condensation unit; 210-Liquid nitrogen storage tank; 220-Intermediate condenser; 221-First heat exchange zone; 222-Second heat exchange zone; 223-Feeding zone; 223a-Buffer section; 223b-Equal diameter feeding section; 300-Compressor; 400-First stage vacuum hood; 500-Second stage vacuum hood. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0038] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0039] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0040] In the description of this application, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0041] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0042] In the existing technology, liquid nitrogen is usually used directly as the heat exchange medium of BF3 condenser in the process of preparing boron isotopes by low temperature distillation. Since the temperature of liquid nitrogen is usually -198℃, it is easy for BF3 to "freeze" in the distillation column during the preparation process, which in turn makes it difficult for the distillation column to operate normally.
[0043] Based on this, the inventors discovered through research that by optimizing the structure of conventional distillation columns (i.e., the column body, the BF3 condenser at the top of the column body, and the reboiler at the bottom of the column body), specifically by adding an intermediate condenser, so that the heat exchange medium that exchanges heat with the gaseous BF3 in the BF3 condenser is not liquid nitrogen but other media with a temperature higher than liquid nitrogen, the problem that the distillation column is prone to malfunction due to BF3 "icing" during the preparation of boron isotopes can be solved.
[0044] The following is a detailed description of a distillation system and method for producing boron isotopes according to this application.
[0045] See Figure 1 In a first aspect, embodiments of this application provide a distillation system 10 for producing boron isotopes, including a distillation column 100 and a condenser 200. The distillation column 100 includes a column body 110, a BF3 condenser 120 located at the top of the column body 110, and a reboiler 130 located at the bottom of the column body 110 (wherein, a feed channel is provided in the middle of the column body 110, and a discharge port is provided at the top and bottom of the column body 110 respectively); the condenser 200 includes a liquid nitrogen storage tank 210 and an intermediate condenser 220. The liquid nitrogen storage tank 210 is connected to a liquid nitrogen source, and the intermediate condenser 220 is connected to a gaseous medium source. The 20 has a first heat exchange zone 221 and a second heat exchange zone 222, which are connected. The first heat exchange zone 221 is configured to exchange heat with the liquid nitrogen provided by the liquid nitrogen storage tank 210, so that the gaseous medium in the first heat exchange zone 221 is at least partially cooled and liquefied after heat exchange to obtain a liquid medium and collect in the second heat exchange zone 222. The second heat exchange zone 222 is configured to exchange heat with the gaseous BF3 in the BF3 condenser 120 using the liquid medium, so that the liquid medium provided by the second heat exchange zone 222 is heated and vaporized after heat exchange and returns to the first heat exchange zone 221.
[0046] In this application, a condensing device 200 is added to the distillation system 10 based on the conventional distillation column 100. Specifically, the condensing device 200 includes a liquid nitrogen storage tank 210 and an intermediate condenser 220. The liquid nitrogen storage tank 210 is connected to a liquid nitrogen source, and the intermediate condenser 220 is connected to a gaseous medium source. The intermediate condenser 220 has a first heat exchange zone 221 and a second heat exchange zone 222 connected to each other. The first heat exchange zone 221 is configured to exchange heat with the liquid nitrogen provided by the liquid nitrogen storage tank 210, so that the gaseous medium located in the first heat exchange zone 221 is at least partially cooled and liquefied after heat exchange to obtain a liquid medium, which then collects in the second heat exchange zone 222. Zone 222 is configured to exchange heat with gaseous BF3 in the BF3 condenser 120 using a liquid medium, so that the liquid medium provided by the second heat exchange zone 222 heats up and vaporizes after heat exchange and returns to the first heat exchange zone 221. By adding an intermediate condenser 220, that is, using the heat exchange medium in the intermediate condenser 220 as an intermediate bridge, the heat exchange medium that exchanges heat with the gaseous BF3 in the BF3 condenser 120 is not liquid nitrogen but a liquid medium with a temperature higher than liquid nitrogen (obtained by liquefaction after heat exchange between the gaseous medium and liquid nitrogen), thereby solving the problem that the distillation column 100 is prone to malfunction due to BF3 "icing" during the preparation of boron isotopes.
[0047] It should be noted that the heat exchange medium in the intermediate condenser 220 always circulates between the gaseous and liquid states. Specifically, in the first heat exchange zone 221, the medium cools down and changes from a gaseous state to a liquid state, which then collects in the second heat exchange zone 222. After the liquid medium exchanges heat with the gaseous BF3 in the BF3 condenser 120, it heats up again and changes back to a gaseous state, returning to the first heat exchange zone 221. Therefore, it is only necessary to introduce the heat exchange medium into the intermediate condenser 220 once.
[0048] It should be noted that the relative positional relationship between the intermediate condenser 220 and the BF3 condenser 120 is not limited. For example, they can be set up separately or as a single unit. The specific arrangement can be adjusted according to actual needs.
[0049] See Figure 1 As an example, along the height direction of the tower body 110, from top to bottom, the liquid nitrogen storage tank 210, the intermediate condenser 220 and the BF3 condenser 120 are connected in sequence. The first heat exchange zone 221 is located at the top of the intermediate condenser 220, the second heat exchange zone 222 is located at the bottom of the intermediate condenser 220, the liquid nitrogen storage tank 210 is connected to the first heat exchange zone 221, and the BF3 condenser 120 is connected to the second heat exchange zone 222.
[0050] In this embodiment, the liquid nitrogen storage tank 210, the intermediate condenser 220 and the BF3 condenser 120 are connected sequentially from top to bottom, that is, the three are set up as a whole, which has the advantages of a more compact overall structure and less space occupation.
[0051] It should be noted that the heat exchange method of the liquid nitrogen storage tank 210, the intermediate condenser 220 and the BF3 condenser 120 is not limited. For example, the heat exchange can be carried out at the connection surface or through pipeline connection and heat exchange. The specific method can be adapted according to actual needs.
[0052] See Figure 1 As an example, the liquid nitrogen storage tank 210 is fitted into the first heat exchange zone 221, and the second heat exchange zone 222 is fitted into the BF3 condenser 120. The liquid nitrogen storage tank 210 and the first heat exchange zone 221, and the second heat exchange zone 222 and the BF3 condenser 120, are connected by corresponding surfaces as heat exchange sites.
[0053] In this embodiment, the liquid nitrogen storage tank 210, the intermediate condenser 220, and the BF3 condenser 120 are arranged in a nested manner with the connecting surface as the heat exchange site. This arrangement has the advantages of a relatively compact overall structure, a reasonable layout, high connection stability, and high heat exchange efficiency. At the same time, this arrangement also makes it easier for the heat exchange medium contained in the intermediate condenser 220 to self-circulate. That is, the gaseous medium at the top cools down and turns into a liquid medium and collects at the bottom, while the liquid medium at the bottom heats up and turns into a gaseous medium and returns to the top.
[0054] See Figure 2 In other possible implementations, the first heat exchange zone 221 may be fitted onto the liquid nitrogen storage tank 210, and the BF3 condenser 120 may be fitted onto the second heat exchange zone 222. The liquid nitrogen storage tank 210 and the first heat exchange zone 221, as well as the second heat exchange zone 222 and the BF3 condenser 120, may use corresponding connecting surfaces as heat exchange sites.
[0055] As an example, the liquid nitrogen storage tank 210 is also equipped with a pressure detection unit and / or a temperature detection unit.
[0056] In this embodiment, after heat exchange, the pressure and temperature inside the liquid nitrogen storage tank 210 will both rise. The liquid nitrogen storage tank 210 is equipped with a pressure detection unit and / or a temperature detection unit to realize real-time monitoring of the state inside the liquid nitrogen storage tank 210, so as to facilitate the determination of whether new liquid nitrogen needs to be added based on the pressure and temperature indicators.
[0057] See Figure 3As an example, along the height direction of the tower body 110, from top to bottom, the intermediate condenser 220 includes a first heat exchange zone 221 and a second heat exchange zone 222 and a conveying zone 223 located between them. The inner diameter of the conveying zone 223 is smaller than the inner diameter of the first heat exchange zone 221 and the inner diameter of the second heat exchange zone 222.
[0058] In this embodiment, the material conveying zone 223 in the intermediate condenser 220 does not participate in heat exchange. Its inner diameter is set to be smaller than the inner diameter of the first heat exchange zone 221 and the second heat exchange zone 222 at both ends. That is, the whole presents a form that is small in the middle and large at both ends. This can reduce manufacturing materials and reduce manufacturing costs. At the same time, it also makes the intermediate condenser 220 have a high heat exchange efficiency.
[0059] See Figure 4 ,in, Figure 4 The liquid level in the text indicates that a portion of the liquid medium is temporarily stored in the buffer section 223a. As an example, along the height direction of the tower body 110, the conveying zone 223 includes a buffer section 223a and equal-diameter conveying sections 223b located at both ends of the buffer section 223a. The inner diameter of the buffer section 223a is larger than the inner diameter of the equal-diameter conveying section 223b. The equal-diameter conveying section 223b located at the upper end is connected to the first heat exchange zone 221, and the equal-diameter conveying section 223b located at the lower end is connected to the second heat exchange zone 222.
[0060] In this embodiment, the conveying zone 223 is configured as a combination of a buffer section 223a and a constant-diameter conveying section 223b. The inner diameter of the buffer section 223a is larger than that of the constant-diameter conveying section 223b. That is, the conveying zone 223 is generally large in the middle and small at both ends. The buffer section 223a can temporarily store a portion of the liquid medium, which can better maintain the temperature stability of the distillation column 100 when the liquid nitrogen is insufficient.
[0061] It should also be noted that the preparation of boron isotopes by cryogenic distillation requires a large amount of refrigerant, resulting in high costs. Therefore, reducing costs and increasing efficiency is a major challenge for this preparation method. Based on this, the structure of the cryogenic distillation system 10 can be further optimized.
[0062] See Figure 5 As an example, the nitrogen outlet of the liquid nitrogen storage tank 210 is connected to the heat exchange medium inlet of the reboiler 130 via a compressor 300.
[0063] In this embodiment, the nitrogen outlet of the liquid nitrogen storage tank 210 is connected to the heat exchange medium inlet of the reboiler 130, that is, the nitrogen generated after the liquid nitrogen heat exchange is used as the heat source of the reboiler 130 to realize the secondary utilization of nitrogen and save manufacturing costs. At the same time, the nitrogen outlet of the liquid nitrogen storage tank 210 and the heat exchange medium inlet of the reboiler 130 are connected through the compressor 300, which facilitates the adjustment of the nitrogen temperature so that the nitrogen has a more suitable temperature after arriving at the reboiler 130, thereby better heating the liquid boron trifluoride and vaporizing it.
[0064] It should be noted that, according to statistics, reusing the nitrogen gas after liquid nitrogen heat exchange as the heat exchange medium in the reboiler 130 can reduce energy consumption by about 20%. Furthermore, if photovoltaic power generation and energy storage technologies can be combined with the cryogenic distillation system 10 in the future, energy consumption is expected to be further reduced.
[0065] As an example, the liquid nitrogen storage tank 210, the intermediate condenser 220, and the BF3 condenser 120 are all spaced apart. The internal cavity of the intermediate condenser 220 is used to communicate with a gaseous medium source. A first heat exchange zone 221 is located at the top of the intermediate condenser 220, and a second heat exchange zone 222 is located at the bottom of the intermediate condenser 220. The side wall of the cavity corresponding to the first heat exchange zone 221 has a first fluid channel that can exchange heat with the cavity. The first fluid channel is connected to the liquid nitrogen storage tank 210 to store the liquid nitrogen. The fluid is introduced into the first fluid channel, so that the gaseous medium located in the first heat exchange zone 221 is at least partially cooled and liquefied after heat exchange and collects into the second heat exchange zone 222. The cavity has a second fluid channel on the side wall corresponding to the second heat exchange zone 222. The second fluid channel is configured to transport the liquid medium to the BF3 condenser 120 for heat exchange with the gaseous BF3 in the BF3 condenser 120, and also to allow the liquid medium to heat up and vaporize after heat exchange and return to the first heat exchange zone 221.
[0066] In this embodiment, the liquid nitrogen storage tank 210, the intermediate condenser 220 and the BF3 condenser 120 are all distributed at intervals, that is, they are set in a separate form and connected and heat exchanged through pipes, which facilitates the assembly and layout of the distillation system 10 when there is not enough vertical space.
[0067] It should be noted that structural or functional units in the distillation system 10 that are not specifically described or limited can be set up in accordance with conventional choices in the art.
[0068] As an example, the height of the tower body 110 is 50~300 m, the inner diameter of the tower body 110 is 10~150 mm, and the tower body 110 can be a single piece with the same inner diameter, or it can be a splicing of multiple tower sections with gradually decreasing inner diameters.
[0069] It should be noted that the tower body 110 can be a plate tower or a packed tower, and the tower body 110 is provided with liquid distribution devices that are spaced apart along the height direction of the tower body 110. The liquid distribution devices can be nozzle type, disc type, pipe type, trough type or trough-disc type.
[0070] As an example, the theoretical number of plates in tower 110 is 1800 to 3600.
[0071] See Figure 6 As an example, the distillation system 10 also includes a first-stage vacuum shroud 400 and a second-stage vacuum shroud 500, both of which are connected to a vacuum unit. The distillation column 100 and the condenser 200 are both located inside the first-stage vacuum shroud 400, and the second-stage vacuum shroud 500 is installed outside the first-stage vacuum shroud 400.
[0072] See Figure 6 As an example, the outer wall of the tower body 110 is also covered with a heat insulation membrane 140, wherein the heat insulation membrane 140 may be a single-sided sprayed metal film, a plastic film or a corrugated sprayed aluminum film.
[0073] As an example, the distillation system 10 is made of materials such as stainless steel, copper, or titanium alloy, which are resistant to low temperatures and boron trifluoride corrosion.
[0074] Secondly, embodiments of this application provide a method for producing boron isotopes, using a distillation system as provided in the first aspect embodiment, comprising the following steps: The raw material is fed into the column for distillation. First, liquid nitrogen from the liquid nitrogen storage tank is used to exchange heat with the gaseous medium in the first heat exchange zone. After the heat exchange, the gaseous medium in the first heat exchange zone is at least partially cooled and liquefied to obtain a liquid medium, which is then collected in the second heat exchange zone. The liquefaction temperature of the gaseous medium is -100 to -120°C. Then, the liquid medium in the second heat exchange zone is used to exchange heat with the gaseous BF3 in the BF3 condenser. After the heat exchange, the liquid medium provided by the second heat exchange zone is heated and vaporized, and then returns to the first heat exchange zone.
[0075] In this application, the method for producing boron isotopes uses a distillation system as provided in the first aspect embodiment. Since it adds an intermediate condenser to the conventional distillation column, and the liquefaction temperature of the heat exchange medium in the intermediate condenser is -100~-120℃, the overall heat exchange process is as follows: liquid nitrogen first exchanges heat with the gaseous medium to cool the gaseous medium and liquefy it into a liquid medium with a temperature close to -100℃, and then exchanges heat with the gaseous BF3 in the BF3 condenser through the liquid medium. This ensures that the heat exchange medium that exchanges heat with the gaseous BF3 in the BF3 condenser is not liquid nitrogen but a liquid medium with a temperature of around -100℃, thereby solving the problem of "icing" inside the distillation column caused by liquid nitrogen directly exchanging heat with the gaseous BF3 in the BF3 condenser.
[0076] As an example, the gaseous medium includes a heat exchange gaseous medium and a buffer gaseous medium, and the volume ratio of the buffer gaseous medium is greater than that of the heat exchange gaseous medium. The heat exchange gaseous medium is selected from at least one of nitrogen trifluoride, carbon tetrafluoride, methane, ethylene and oxygen, and the buffer gaseous medium is selected from at least one of hydrogen, neon and helium.
[0077] In this embodiment, the gaseous medium is composed of the aforementioned heat exchange gaseous medium and buffer gaseous medium, and the volume ratio of the buffer gaseous medium is greater than that of the heat exchange gaseous medium. This ensures that the overall pressure change of the gaseous medium is small during liquefaction and vaporization (pressure change will cause temperature change), thereby maintaining the temperature of the first and second heat exchange zones of the intermediate condenser within a suitable range, which helps to improve the stability of the distillation system.
[0078] As an example, after the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure inside the intermediate condenser is 1 to 50 bar, for example, but not limited to any one of the following pressures or any range between two: 1 bar, 5 bar, 10 bar, 20 bar, 30 bar, 40 bar and 50 bar.
[0079] In this embodiment, after the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure inside the intermediate condenser is controlled within the aforementioned range so that the temperature of the liquid medium is closer to -100°C, thereby more accurately controlling the temperature of the distillation column at a suitable separation temperature.
[0080] As an example, the heat exchange gaseous medium is oxygen, and after the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure in the intermediate condenser is 5 to 10 bar, for example, but not limited to any one of 5 bar, 6 bar, 7 bar, 8 bar, 9 bar and 10 bar or any range between two of them.
[0081] As an example, the heat exchange gaseous medium is ethylene, and after the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure in the intermediate condenser is 1 to 2 bar, for example, but not limited to any one of the pressures of 1 bar, 1.2 bar, 1.4 bar, 1.6 bar, 1.8 bar and 2.0 bar or any range between two of them.
[0082] As an example, the heat exchange gaseous medium is carbon tetrafluoride and / or nitrogen trifluoride, and after liquefaction, the pressure inside the intermediate condenser is 2 to 6 bar, for example, but not limited to any one of 2 bar, 2.5 bar, 3 bar, 3.5 bar, 4 bar, 4.5 bar, 5 bar, 5.5 bar and 6 bar or any range between two of them.
[0083] As an example, the heat exchange gaseous medium is methane, and after the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure in the intermediate condenser is 15~30 bar, for example, but not limited to any one of 15 bar, 18 bar, 20 bar, 22 bar, 24 bar, 26 bar, 28 bar and 30 bar or any range between two of them.
[0084] In this embodiment, for different types of heat exchange gaseous media, the pressure of the gaseous media after liquefaction is limited to the above range, which makes the temperature of the liquid medium closer to -100°C.
[0085] As an example, the nitrogen outlet of the liquid nitrogen storage tank is connected to the heat exchange medium inlet of the reboiler via a compressor, and the compression ratio of the compressor is 2 to 20, for example, but not limited to any one of the compression ratios of 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 or any range between the two.
[0086] In this embodiment, the compression ratio of the compressor is limited to the above-mentioned range so that the temperature of the nitrogen gas is maintained in the range of -55 to -95°C when it reaches the reboiler, thereby facilitating heat exchange with liquid boron trifluoride and causing it to vaporize.
[0087] As an example, the tower body is provided with liquid distribution devices that are spaced apart along the height of the tower body, so that the pressure drop inside the tower body is 0.5~250 Pa / m.
[0088] In this embodiment, limiting the pressure drop within the tower body to the aforementioned range helps reduce energy consumption and production costs.
[0089] As an example, the theoretical number of plates in the tower is 1800 to 3600, so that the reflux ratio of the tower is 200 to 1000.
[0090] As an example, in the distillation process, the ratio of distillate to feed is set to 0.75 to 0.95.
[0091] As an example, the distillation system also includes a first-stage vacuum hood and a second-stage vacuum hood, both of which are connected to a vacuum unit. The distillation column and condenser are located inside the first-stage vacuum hood, while the second-stage vacuum hood is fitted outside it. The vacuum level inside the first-stage vacuum hood is 10. -2 ~10 -4 Pa, the vacuum level inside the second-stage vacuum chamber is 10. -1 ~10 -3 Pa.
[0092] It should be noted that processes or steps not specifically described or limited during production can be set according to conventional methods in this field.
[0093] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A distillation system for producing boron isotopes, characterized in that, include: A distillation column, the distillation column comprising a column body and a BF3 condenser located at the top of the column body and a reboiler located at the bottom of the column body; A condensation device includes a liquid nitrogen storage tank and an intermediate condenser. The liquid nitrogen storage tank is connected to a liquid nitrogen source, and the intermediate condenser is connected to a gaseous medium source. The intermediate condenser has a first heat exchange zone and a second heat exchange zone, which are connected. The first heat exchange zone is configured to exchange heat with the liquid nitrogen provided by the liquid nitrogen storage tank, such that the gaseous medium located in the first heat exchange zone is at least partially cooled and liquefied after heat exchange to obtain a liquid medium, which then collects in the second heat exchange zone. The second heat exchange zone is configured to exchange heat with the gaseous BF3 in the BF3 condenser using the liquid medium, such that the liquid medium provided by the second heat exchange zone is heated and vaporized after heat exchange and returns to the first heat exchange zone. Along the height direction of the tower body, from top to bottom, the liquid nitrogen storage tank, the intermediate condenser, and the BF3 condenser are connected in sequence, wherein the first heat exchange zone is located at the top of the intermediate condenser, the second heat exchange zone is located at the bottom of the intermediate condenser, the liquid nitrogen storage tank is connected to the first heat exchange zone, and the BF3 condenser is connected to the second heat exchange zone; Along the height direction of the tower body, from top to bottom, the intermediate condenser includes a first heat exchange zone and a second heat exchange zone and a material conveying zone located between them. The inner diameter of the material conveying zone is smaller than the inner diameter of the first heat exchange zone and the inner diameter of the second heat exchange zone. The liquid nitrogen storage tank, the intermediate condenser, and the BF3 condenser are all spaced apart. The internal cavity of the intermediate condenser is used to communicate with the gaseous medium source. The first heat exchange zone is located at the top of the intermediate condenser, and the second heat exchange zone is located at the bottom of the intermediate condenser. The cavity has a first fluid channel on the side wall corresponding to the first heat exchange zone, which is capable of exchanging heat with the cavity. The first fluid channel is connected to the liquid nitrogen storage tank to allow liquid nitrogen to be introduced into the first fluid channel, so that the gaseous medium located in the first heat exchange zone will at least partially cool down and liquefy after heat exchange and collect in the second heat exchange zone. The cavity has a second fluid channel on the side wall corresponding to the second heat exchange zone. The second fluid channel is configured to transport the liquid medium to the BF3 condenser for heat exchange with the gaseous BF3 in the BF3 condenser, and also to allow the liquid medium to heat up and vaporize after heat exchange and return to the first heat exchange zone.
2. The distillation system for producing boron isotopes according to claim 1, characterized in that, The liquid nitrogen storage tank is fitted into the first heat exchange zone, and the second heat exchange zone is fitted into the BF3 condenser. The liquid nitrogen storage tank and the first heat exchange zone, as well as the second heat exchange zone and the BF3 condenser, are connected by corresponding surfaces as heat exchange sites.
3. The distillation system for producing boron isotopes according to claim 1, characterized in that, The first heat exchange zone is fitted onto the liquid nitrogen storage tank, and the BF3 condenser is fitted onto the second heat exchange zone. The liquid nitrogen storage tank and the first heat exchange zone, as well as the second heat exchange zone and the BF3 condenser, are connected by corresponding surfaces as heat exchange sites.
4. The distillation system for producing boron isotopes according to any one of claims 1 to 3, characterized in that, The liquid nitrogen storage tank is also equipped with a pressure detection unit and / or a temperature detection unit.
5. The distillation system for producing boron isotopes according to claim 1, characterized in that, Along the height direction of the tower body, the material conveying zone includes a buffer section and equal-diameter material conveying sections located at both ends of the buffer section, and the inner diameter of the buffer section is larger than the inner diameter of the equal-diameter material conveying sections. The equal-diameter material conveying section located at the upper end is connected to the first heat exchange zone, and the equal-diameter material conveying section located at the lower end is connected to the second heat exchange zone.
6. The distillation system for producing boron isotopes according to any one of claims 1 to 3, characterized in that, The nitrogen outlet of the liquid nitrogen storage tank is connected to the heat exchange medium inlet of the reboiler via a compressor.
7. A method for producing boron isotopes, characterized in that, Production using the distillation system as described in any one of claims 1 to 6 includes the following steps: The raw material is transported into the column for distillation. First, the liquid nitrogen provided by the liquid nitrogen storage tank is used to exchange heat with the gaseous medium in the first heat exchange zone. After the heat exchange, the gaseous medium in the first heat exchange zone is at least partially cooled and liquefied to obtain the liquid medium, which is then collected in the second heat exchange zone. The liquefaction temperature of the gaseous medium is -100~-120℃. Then, the liquid medium located in the second heat exchange zone is used to exchange heat with the gaseous BF3 in the BF3 condenser, so that the liquid medium provided by the second heat exchange zone is heated and vaporized after the heat exchange and returns to the first heat exchange zone.
8. The method for producing boron isotopes according to claim 7, characterized in that, The gaseous medium includes a heat exchange gaseous medium and a buffer gaseous medium, and the volume ratio of the buffer gaseous medium is greater than that of the heat exchange gaseous medium. The heat exchange gaseous medium is selected from at least one of nitrogen trifluoride, carbon tetrafluoride, methane, ethylene and oxygen, and the buffer gaseous medium is selected from at least one of hydrogen, neon and helium.
9. The method for producing boron isotopes according to claim 8, characterized in that, After the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure inside the intermediate condenser is 1~50 bar.
10. The method for producing boron isotopes according to claim 9, characterized in that, The heat exchange gaseous medium is oxygen, and the pressure inside the intermediate condenser after the heat exchange gaseous medium is liquefied is 5~10 bar.
11. The method for producing boron isotopes according to claim 9, characterized in that, The heat exchange gaseous medium is ethylene, and the pressure inside the intermediate condenser after the heat exchange gaseous medium is liquefied is 1~2 bar.
12. The method for producing boron isotopes according to claim 9, characterized in that, The heat exchange gaseous medium is nitrogen trifluoride and / or carbon tetrafluoride, and the pressure inside the intermediate condenser after liquefaction of the heat exchange gaseous medium is 2~6 bar.
13. The method for producing boron isotopes according to claim 9, characterized in that, The heat exchange gaseous medium is methane, and after the heat exchange gaseous medium in the intermediate condenser is liquefied, the pressure inside the intermediate condenser is 15~30 bar.
14. The method for producing boron isotopes according to any one of claims 7 to 13, characterized in that, The nitrogen outlet of the liquid nitrogen storage tank is connected to the heat exchange medium inlet of the reboiler via a compressor, and the compression ratio of the compressor is 2 to 20.