Method and device for separating boron isotope through low-temperature rectification

Abstract

The invention provides a method and device for separating boron isotopes through low-temperature rectification, and relates to the technical field of isotope separation. According to the method for separating the boron isotope through low-temperature rectification, ethylene serves as a circulating medium to provide cold energy and heat energy, continuous operation is adopted, the method is low in equipment investment, easy to operate, large in production capacity, high in product yield and good in economical efficiency, the problem that liquid nitrogen serves as a cooling medium, so that BF3 is solidified and blocks a pipeline can be solved, and the production efficiency is improved. And the problem of high energy consumption caused by incapability of serving as a circulating working medium of a rectifying tower indirect heat pump process due to low critical temperature of the liquid nitrogen can be avoided. The device comprises a first-stage tower, a second-stage tower and a circulating refrigeration device, the circulating refrigeration device takes ethylene as a circulating medium, the system energy consumption of the indirect heat pump double-effect BF3 low-temperature rectification method device taking ethylene as a circulating working medium is greatly reduced, and the pipeline blockage risk is reduced. The number of moving devices in the device is reduced, and long-term stable operation of the device is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of isotope separation, and in particular to a method and device for separating boron isotopes by cryogenic distillation. Background Art

[0002] Boron contains two stable isotopes in nature, boron 10 and boron 11, with natural abundances of 19.78% and 80.22% respectively. High-abundance and high-purity boron 10 is one of the important materials in the nuclear industry (control rods, detectors and chemical control agents, etc.), military equipment (neutron protection) and medical fields (targeted cancer treatment). 11 BF3 products are widely used in chip production and can be used as raw materials for preparing optical fiber preforms in the production of semiconductor devices and integrated circuits.

[0003] There are many methods to enrich boron isotopes, such as: boron trifluoride chemical exchange distillation, boron trifluoride cryogenic distillation, boric acid solution ion exchange, laser separation and adsorption separation. Cryogenic distillation uses the slight difference in saturated vapor pressure between isotope atoms or molecules to achieve the separation of isotope components. The separation of carbon, hydrogen and oxygen isotope systems is achieved through cryogenic separation technology. Studies have found that the BF3 separation factor is 1.008 at normal pressure, and the BF3 separation tower is 1.008 after 480 hours. 10 The concentration of B can reach 95% to 96%. Therefore, BF3 as a separation material has the advantages of large separation factor, stable raw materials, fast separation speed, relatively short equilibrium time, etc., which is simpler to achieve large-scale industrial production.

[0004] However, the process consumes a lot of energy, and has strict requirements on the purification of raw gas, automatic control instruments, equipment processing level, etc., and has extremely high requirements for the insulation of the tower body, and requires strict control of temperature and pressure. How to reduce the energy consumption of this process is the focus of research. At the same time, the boiling point of BF3 at normal pressure is -100℃, and the freezing point is -126.8℃. Liquid nitrogen is commonly used as a cooling medium in industry. The critical temperature of liquid nitrogen is -147℃ and the critical pressure is 3.4MPa. If liquid nitrogen is used as a cooling medium, even if the working pressure of liquid nitrogen is increased, the entire system will still have the risk of BF3 solidification and clogging the pipeline. At the same time, because the critical temperature is much lower than the boiling point of BF3 at normal pressure, liquid nitrogen cannot be used as a circulating working fluid in the indirect heat pump process of the distillation tower, and the cooling capacity of the reboiler at the bottom of the distillation tower cannot be effectively recovered, and the energy consumption of the system cannot be further reduced. Summary of the invention

[0005] The purpose of the present application is to provide a method and device for separating boron isotopes by cryogenic distillation, aiming to solve the problems of BF3 solidification and clogging of pipelines and high energy consumption in existing cryogenic distillation towers using liquid nitrogen as a cooling medium.

[0006] To achieve the above objectives, the present application provides a method for separating boron isotopes by cryogenic distillation, comprising:

[0007] The natural abundance BF3 raw material is introduced into the first stage tower for the first low temperature distillation to obtain the first tower top material and the first tower bottom material, wherein the first tower bottom material is a boron-10 abundance of not less than 99%. 10 BF3 products;

[0008] The first tower top material enters the second tower for a second low temperature distillation to obtain a second tower top material and a second tower bottom material, wherein the second tower top material has a boron-11 abundance of not less than 99%. 11 BF3 product, the second tower bottom material is mixed with the BF3 raw material and then recycled;

[0009] The top pressure of the first tower is 0.25 MPa to 0.65 MPa; the top pressure of the second tower is 0.1 MPa to 0.45 MPa;

[0010] The first-stage tower and the second-stage tower use ethylene as a circulating medium to provide cold and heat.

[0011] In some embodiments, at least one of the following conditions is met:

[0012] A. The bottom temperature and top temperature of the first-stage tower are -65°C to -85°C respectively;

[0013] B. The bottom temperature and top temperature of the second stage tower are -75°C to -95°C respectively;

[0014] C. The second tower bottom material is mixed with the BF3 raw material, and then heated and pressurized in a cold trap and then introduced into the first tower;

[0015] D. When condition C is met, the temperature of the second bottom material after mixing with the BF3 raw material and heating and pressurizing in the cold trap is -65°C to 40°C, and the pressure is 0.25MPa to 1.5MPa;

[0016] E. The environmental vacuum degree of the first stage tower is 0.0001Pa~10Pa.

[0017] In some embodiments, the first stage tower and the second stage tower provide cold and heat using ethylene as the circulating medium, comprising:

[0018] The ethylene is pressurized and heated by a compressor, then cooled by a heat exchanger and cooled by heat exchange with the compressor inlet stream to obtain high-pressure gas-phase ethylene, and the high-pressure gas-phase ethylene is transported to the bottom reboiler of the first-stage tower as a heat source, and condensed into a first liquid-phase ethylene by heat exchange;

[0019] The first liquid phase ethylene is subjected to medium-pressure gas-liquid separation to obtain medium-pressure liquid phase ethylene and first gas phase ethylene, and the medium-pressure liquid phase ethylene is transported to the top condenser of the first-stage tower as a cold source, and evaporated into medium-pressure gas phase ethylene by heat exchange;

[0020] The medium-pressure gas phase ethylene is transported to the bottom reboiler of the second-stage tower as a heat source, and condensed into second liquid phase ethylene by heat exchange;

[0021] The second liquid phase ethylene is subjected to low-pressure gas-liquid separation to obtain low-pressure liquid phase ethylene and second gas phase ethylene, and the low-pressure liquid phase ethylene is transported to the top condenser of the second tower as a cold source, and evaporated into low-pressure gas phase ethylene by heat exchange;

[0022] The low-pressure gas-phase ethylene is mixed with the first gas-phase ethylene and the second gas-phase ethylene to obtain the compressor inlet logistics.

[0023] In some embodiments, at least one of the following conditions is met:

[0024] A. The temperature of ethylene after being pressurized and heated by a compressor is 40℃~160℃ and the pressure is 0.3MPa~1.5MPa;

[0025] B. The temperature after cooling by the heat exchanger is 40°C to 160°C;

[0026] C. The temperature after heat exchange and cooling with the compressor inlet logistics is -70℃~-30℃;

[0027] D. The temperature of the medium-pressure liquid phase ethylene is -57°C to -93°C, and the pressure is 0.15MPa to 1.0MPa;

[0028] E. The temperature of the low-pressure liquid phase ethylene is -67°C to -103°C, and the pressure is 0.1MPa to 0.7MPa;

[0029] F. The temperature of the compressor inlet logistics is -30℃~30℃, and the pressure is 0.1MPa~0.7MPa.

[0030] The present application also provides a device for separating boron isotopes by cryogenic distillation, which is used to perform the above-mentioned method for separating boron isotopes by cryogenic distillation, comprising: a first-stage tower, a second-stage tower and a circulating refrigeration device;

[0031] The first stage tower is provided with a feed inlet in the tower and a 10 The BF3 product extraction port, the top of the first-stage tower is connected to the middle of the second-stage tower, and the top of the second-stage tower is provided with 11 BF3 product extraction port, the bottom of the second-stage tower is connected to the feed port;

[0032] The first-stage tower comprises a first-stage tower condenser arranged at the top of the tower and a first-stage tower reboiler arranged at the bottom of the tower; the second-stage tower comprises a second-stage tower condenser arranged at the top of the tower and a second-stage tower reboiler arranged at the bottom of the tower;

[0033] The circulating refrigeration device is connected with the first-stage tower condenser, the first-stage tower reboiler, the second-stage tower condenser, and the second-stage tower reboiler.

[0034] In some embodiments, the circulating refrigeration device includes: a compressor, a heat exchanger, a medium-pressure gas-liquid separation tank, and a low-pressure gas-liquid separation tank;

[0035] The outlet of the compressor is connected to the heat exchanger, and the inlet of the compressor is connected to the medium-pressure gas-liquid separation tank, the low-pressure gas-liquid separation tank and the second-stage tower condenser;

[0036] The heat exchanger is connected to the first-stage tower reboiler, the medium-pressure gas-liquid separation tank is connected to the first-stage tower condenser and the first-stage tower reboiler, the low-pressure gas-liquid separation tank is connected to the second-stage tower condenser and the second-stage tower reboiler, and the first-stage tower condenser is connected to the second-stage tower reboiler.

[0037] In some embodiments, the heat exchanger includes: a circulating water heat exchanger, a chilled water heat exchanger and a compressor inlet logistics heat exchanger, the circulating water heat exchanger is connected to the outlet of the compressor, the chilled water heat exchanger is connected to the circulating water heat exchanger, the compressor inlet logistics heat exchanger is connected to the chilled water heat exchanger and the first-stage tower reboiler;

[0038] The inlet of the compressor is connected to the medium-pressure gas-liquid separation tank, the low-pressure gas-liquid separation tank and the second-stage tower condenser through the compressor inlet logistics heat exchanger.

[0039] In some embodiments, the medium-pressure gas-liquid separation tank includes: a first inlet, a first tank top outlet, and a first tank bottom outlet; the first-stage tower reboiler is connected to the first inlet, the first tank top outlet is connected to the compressor inlet, and the first tank bottom outlet is connected to the first-stage tower condenser through a first pump.

[0040] In some embodiments, the low-pressure gas-liquid separation tank includes: a second inlet, a second tank top outlet, and a second tank bottom outlet; the second stage tower reboiler is connected to the second inlet, the second tank top outlet is connected to the compressor inlet, and the second tank bottom outlet is connected to the second stage tower condenser through a second pump.

[0041] In some embodiments, the apparatus for separating boron isotopes by cryogenic distillation further comprises at least one of the following structures:

[0042] A. a feed low temperature cold trap, wherein the feed low temperature cold trap is connected to the feed port;

[0043] B. an aluminum polyester film, the aluminum polyester film being wrapped around the surface of the first-stage tower and the second-stage tower;

[0044] C. a tower well vacuum jacket, arranged around the first-stage tower;

[0045] D. When condition C is satisfied, it further comprises an outer jacket, which is arranged outside the vacuum jacket of the tower well.

[0046] Compared with the prior art, the beneficial effects of this application include:

[0047] The method for separating boron isotopes by low-temperature distillation provided in the present application uses ethylene as a circulating medium to provide cold and heat. Since the boiling point of ethylene at normal pressure is -103.7°C, which is much higher than the freezing point of BF3, there is no risk of BF3 solidifying and blocking the pipeline, and the critical temperature of ethylene is 9.2°C, which is much higher than the operating temperature of the BF3 low-temperature distillation method, so that ethylene can be used as a circulating working fluid in the indirect heat pump process of the distillation tower to reduce energy consumption. The method adopts continuous operation, with low equipment investment, simple operation, large production capacity, high product yield, good economy, and can avoid the problem of BF3 solidifying and blocking the pipeline due to the use of liquid nitrogen as a cooling medium, and can also avoid the problem of high energy consumption due to the low critical temperature of liquid nitrogen and being unable to be used as a circulating working fluid in the indirect heat pump process of the distillation tower.

[0048] The device for separating boron isotopes by cryogenic distillation provided in the present application comprises a first-stage tower, a second-stage tower and a circulating refrigeration device, wherein the circulating refrigeration device uses ethylene as a circulating medium. Since the BF3 separation factor is insensitive to changes in pressure, by increasing the operating pressure at the top of the first-stage tower, the liquid circulating ethylene is heated up by the first-stage tower condenser and becomes gaseous ethylene. In the next step, it can be directly used as a heat source for the reboiler of the second-stage tower to provide heat to re-phase into a liquid state, further reducing the energy consumption of the refrigeration device using ethylene as a circulating working fluid. The device is an indirect heat pump double-effect BF3 cryogenic distillation method device using ethylene as a circulating working fluid, which greatly reduces the system energy consumption and reduces the risk of pipeline blockage. The number of moving equipment in the device is reduced, ensuring the long-term stable operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0050] Figure 1 This is a schematic diagram of the apparatus for separating boron isotopes by cryogenic distillation according to the present application.

[0051] Reference numerals:

[0052] 100-device for separating boron isotopes by low-temperature distillation; 10-first-stage tower; 12-first-stage tower condenser; 14-first-stage tower reboiler; 20-second-stage tower; 22-second-stage tower condenser; 24-second-stage tower reboiler; 30-circulating refrigeration device; 31-compressor; 32-heat exchanger; 321-circulating water heat exchanger; 322-chilled water heat exchanger; 323-compressor inlet logistics heat exchanger; 33-medium-pressure gas-liquid separation tank; 331-first inlet; 332-first tank top outlet; 333-first tank bottom outlet; 334-first pump; 34-low-pressure gas-liquid separation tank; 341-second inlet; 342-second tank top outlet; 343-second tank bottom outlet; 344-second pump; 40-feed low-temperature cold trap. DETAILED DESCRIPTION

[0053] As used herein:

[0054] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0055] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0056] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0057] In these examples, parts and percentages are by mass unless otherwise indicated.

[0058] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0059] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0060] The present application provides a method for separating boron isotopes by cryogenic distillation, comprising:

[0061] S100: BF3 raw material with natural abundance is introduced into the first stage tower for first low temperature distillation to obtain first tower top material and first tower bottom material, wherein the first tower bottom material has a boron-10 abundance of not less than 99%. 10 BF3 products.

[0062] S200: The first tower top material enters the second tower for a second low-temperature rectification to obtain a second tower top material and a second tower bottom material, wherein the second tower top material has a boron-11 abundance of not less than 99%. 11 BF3 product, the second tower bottom material is mixed with the BF3 raw material and then recycled.

[0063] Wherein, the tower top pressure of the first tower is 0.25MPa~0.65MPa, for example, it can be 0.25MPa, 0.30MPa, 0.35MPa, 0.40MPa, 0.45MPa, 0.50MPa, 0.55MPa, 0.60MPa, 0.65MPa or any value between 0.25MPa and 0.65MPa; the tower top pressure of the second tower is 0.1MPa~0.45MPa, for example, it can be 0.1MPa, 0.15MPa, 0.20MPa, 0.25MPa, 0.30MPa, 0.35MPa, 0.40MPa, 0.45MPa or any value between 0.1MPa and 0.45MPa.

[0064] The first-stage tower and the second-stage tower use ethylene as a circulating medium to provide cooling and heat. Ethylene can be used as the circulating medium of the first-stage tower and the second-stage tower respectively to provide cooling and heat to the first-stage tower and the second-stage tower respectively, that is, the circulating medium of the first-stage tower and the second-stage tower does not circulate between the two towers, but only circulates in a single tower; ethylene can also be used as the circulating medium of the first-stage tower and the second-stage tower at the same time, that is, ethylene circulates in the device including the first-stage tower and the second-stage tower to provide cooling and heat for the entire device.

[0065] The method for separating boron isotopes by low-temperature distillation provided in the present application uses ethylene as a circulating medium to provide cold and heat. Since the boiling point of ethylene at normal pressure is -103.7°C, which is much higher than the freezing point of BF3, there is no risk of BF3 solidifying and blocking the pipeline, and the critical temperature of ethylene is 9.2°C, which is much higher than the operating temperature of the BF3 low-temperature distillation method, so that ethylene can be used as a circulating working fluid in the indirect heat pump process of the distillation tower to reduce energy consumption. The method adopts continuous operation, with low equipment investment, simple operation, large production capacity, high product yield, good economy, and can avoid the problem of BF3 solidifying and blocking the pipeline due to the use of liquid nitrogen as a cooling medium, and can also avoid the problem of high energy consumption due to the low critical temperature of liquid nitrogen and being unable to be used as a circulating working fluid in the indirect heat pump process of the distillation tower.

[0066] In some embodiments, the bottom temperature and the top temperature of the first tower are respectively -65°C to -85°C, for example, -65°C, -70°C, -75°C, -80°C, -85°C or any value between -65°C and -85°C.

[0067] In some embodiments, the bottom temperature and the top temperature of the second tower are respectively -75°C to -95°C, for example, -75°C, -80°C, -85°C, -90°C, -95°C or any value between -75°C and -95°C.

[0068] In some embodiments, the second tower bottom material is mixed with the BF3 raw material and then heated and pressurized in a cold trap before being passed into the first tower; the temperature of the second tower bottom material after being mixed with the BF3 raw material and then heated and pressurized in a cold trap is -65°C to 40°C, and the pressure is 0.25MPa to 1.5MPa.

[0069] In some embodiments, the environmental vacuum degree of the first-stage tower is 0.0001Pa to 10Pa. The first-stage tower is in a vacuum environment to reduce conductive heat loss.

[0070] In some embodiments, the first stage tower and the second stage tower provide cold and heat using ethylene as the circulating medium, comprising:

[0071] The ethylene is pressurized and heated by a compressor, then cooled by a heat exchanger and cooled by heat exchange with the compressor inlet stream to obtain high-pressure gas-phase ethylene, and the high-pressure gas-phase ethylene is transported to the bottom reboiler of the first-stage tower as a heat source, and condensed into a first liquid-phase ethylene by heat exchange;

[0072] The first liquid phase ethylene is subjected to medium-pressure gas-liquid separation to obtain medium-pressure liquid phase ethylene and first gas phase ethylene, and the medium-pressure liquid phase ethylene is transported to the top condenser of the first-stage tower as a cold source, and evaporated into medium-pressure gas phase ethylene by heat exchange;

[0073] The medium-pressure gas phase ethylene is transported to the bottom reboiler of the second-stage tower as a heat source, and condensed into second liquid phase ethylene by heat exchange;

[0074] The second liquid phase ethylene is subjected to low-pressure gas-liquid separation to obtain low-pressure liquid phase ethylene and second gas phase ethylene, and the low-pressure liquid phase ethylene is transported to the top condenser of the second tower as a cold source, and evaporated into low-pressure gas phase ethylene by heat exchange;

[0075] The low-pressure gas-phase ethylene is mixed with the first gas-phase ethylene and the second gas-phase ethylene to obtain the compressor inlet logistics.

[0076] In some embodiments, the temperature of ethylene after being pressurized and heated by a compressor is 40° C. to 160° C., and the pressure is 0.3 MPa to 1.5 MPa.

[0077] In some embodiments, the temperature after cooling by the heat exchanger is 40°C to 160°C.

[0078] In some embodiments, the temperature of the logistics after heat exchange and cooling with the compressor inlet is -70°C to -30°C.

[0079] In some embodiments, the medium-pressure liquid phase ethylene has a temperature of -57°C to -93°C and a pressure of 0.15 MPa to 1.0 MPa.

[0080] In some embodiments, the temperature of the low-pressure liquid phase ethylene is -67°C to -103°C, and the pressure is 0.1 MPa to 0.7 MPa.

[0081] In some embodiments, the temperature of the compressor inlet logistics is -30°C to 30°C, and the pressure is 0.1 MPa to 0.7 MPa.

[0082] The present application also provides a device 100 for separating boron isotopes by cryogenic distillation, which is used to perform the above-mentioned method for separating boron isotopes by cryogenic distillation. Figure 1 , comprising: a first-stage tower 10, a second-stage tower 20 and a circulating refrigeration device 30;

[0083] The first stage tower 10 is provided with a feed inlet in the tower and a10 The BF3 product extraction port, the top of the first stage tower 10 is connected to the middle of the second stage tower 20, and the top of the second stage tower 20 is provided with 11 BF3 product extraction port, the bottom of the second stage tower 20 is connected to the feed port;

[0084] The first-stage tower 10 includes a first-stage tower condenser 12 disposed at the top of the tower and a first-stage tower reboiler 14 disposed at the bottom of the tower; the second-stage tower 20 includes a second-stage tower condenser 22 disposed at the top of the tower and a second-stage tower reboiler 24 disposed at the bottom of the tower;

[0085] The circulating refrigeration device 30 is connected to the first-stage tower condenser 12 , the first-stage tower reboiler 14 , the second-stage tower condenser 22 , and the second-stage tower reboiler 24 .

[0086] The circulating refrigeration device 30 of the low-temperature distillation and separation of boron isotopes device 100 provided in the present application uses ethylene as the circulating medium. Since the BF3 separation factor is insensitive to changes in pressure, by increasing the operating pressure at the top of the first-stage tower 10, the liquid circulating ethylene is heated by the first-stage tower condenser 12 and becomes gaseous ethylene. In the next step, it can be directly used as a heat source for the second-stage tower reboiler 24 to provide heat to re-phase into a liquid state, further reducing the energy consumption of the refrigeration device using ethylene as the circulating working medium. The device is an indirect heat pump double-effect BF3 low-temperature distillation method device using ethylene as the circulating working medium, which greatly reduces the system energy consumption and reduces the risk of pipeline blockage. The number of moving equipment in the device is reduced, ensuring the long-term stable operation of the device.

[0087] In some embodiments, please refer to Figure 1 The circulating refrigeration device 30 includes: a compressor 31, a heat exchanger 32, a medium-pressure gas-liquid separation tank 33 and a low-pressure gas-liquid separation tank 34;

[0088] The outlet of the compressor 31 is connected to the heat exchanger 32, and the inlet of the compressor 31 is connected to the medium-pressure gas-liquid separation tank 33, the low-pressure gas-liquid separation tank 34 and the second-stage tower condenser 22;

[0089] The heat exchanger 32 is connected to the first-stage tower reboiler 14, the medium-pressure gas-liquid separation tank 33 is connected to the first-stage tower condenser 12 and the first-stage tower reboiler 14, the low-pressure gas-liquid separation tank 34 is connected to the second-stage tower condenser 22 and the second-stage tower reboiler 24, and the first-stage tower condenser 12 is connected to the second-stage tower reboiler 24.

[0090] The compressor 31 pressurizes and heats the ethylene, the heat exchanger 32 cools the pressurized and heated ethylene, and the medium-pressure gas-liquid separation tank 33 and the low-pressure gas-liquid separation tank 34 separate the liquid-phase ethylene.

[0091] In some embodiments, please refer to Figure 1 , the heat exchanger 32 includes: a circulating water heat exchanger 321, a chilled water heat exchanger 322 and a compressor inlet logistics heat exchanger 323, the circulating water heat exchanger 321 is connected to the outlet of the compressor 31, the chilled water heat exchanger 322 is connected to the circulating water heat exchanger 321, the compressor inlet logistics heat exchanger 323 is connected to the chilled water heat exchanger 322 and the first-stage tower reboiler 14;

[0092] The inlet of the compressor 31 is connected to the medium-pressure gas-liquid separation tank 33 , the low-pressure gas-liquid separation tank 34 and the second-stage tower condenser 22 through the compressor inlet logistics heat exchanger 323 .

[0093] The circulating water heat exchanger 321, the chilled water heat exchanger 322 and the compressor inlet logistics heat exchanger 323 can make the ethylene temperature drop more fully.

[0094] In some embodiments, the medium-pressure gas-liquid separation tank 33 includes: a first inlet 331, a first tank top outlet 332, and a first tank bottom outlet 333; the first-stage tower reboiler 14 is connected to the first inlet 331, the first tank top outlet 332 is connected to the inlet of the compressor 31, and the first tank bottom outlet 333 is connected to the first-stage tower condenser 12 through a first pump 334.

[0095] In some embodiments, the low-pressure gas-liquid separation tank 34 includes: a second inlet 341, a second tank top outlet 342, and a second tank bottom outlet 343; the second stage tower reboiler 24 is connected to the second inlet 341, the second tank top outlet 342 is connected to the inlet of the compressor 31, and the second tank bottom outlet 343 is connected to the second stage tower condenser 22 through a second pump 344.

[0096] In some embodiments, the apparatus 100 for separating boron isotopes by cryogenic distillation further comprises a feed cryogenic cold trap 40 , which is connected to the feed port and is used to increase the temperature and pressure of the raw material and the second-stage tower bottom material.

[0097] In some embodiments, the apparatus 100 for separating boron isotopes by cryogenic distillation further comprises an aluminum polyester film, which is wrapped around the surface of the first-stage tower 10 and the second-stage tower 20 to reduce radiation heat loss.

[0098] In some embodiments, the apparatus 100 for separating boron isotopes by cryogenic distillation further comprises a tower well vacuum jacket disposed around the first-stage tower 10, and the well vacuum jacket is evacuated to place the first-stage tower 10 in a vacuum environment to reduce conductive heat loss.

[0099] In some embodiments, the apparatus 100 for separating boron isotopes by cryogenic distillation further comprises an outer jacket, which is disposed outside the vacuum jacket of the tower well and is used to protect the apparatus from corrosion by water and air.

[0100] In some embodiments, the first tower 10 and the second tower 20 are packed towers, and liquid distributors are installed at certain heights to evenly distribute the liquid flowing down from the top of the tower to increase the heat and mass transfer efficiency.

[0101] The operation process of the device 100 for separating boron isotopes by cryogenic distillation is as follows: first, the purified BF3 raw material is mixed with the liquid at the bottom of the second-stage tower 20 and sent to the feed cryogenic cold trap 40, and then sent to the first-stage tower 10 for cryogenic distillation after the cold trap is heated and pressurized, and a high-purity and high-abundance boron isotope is obtained at the bottom of the first-stage tower 10. 10 The BF3 product is sent from the top of the first tower 10 to the second tower 20 for low-temperature distillation by self-pressure, and the top of the second tower 20 obtains high-purity and rich BF3. 11 The BF3 product, the liquid at the bottom of the second tower 20 is circulated and returned to the inlet of the feed low temperature cold trap 40 to be mixed with the fresh raw material.

[0102] The circulating refrigeration device 30 with ethylene as the circulating working fluid provides cold and heat for the low-temperature distillation separation device 100 of boron isotopes. The ethylene after being pressurized and heated by the compressor 31 is cooled by the circulating water heat exchanger 321 and the chilled water heat exchanger 322, and then heat-exchanged with the compressor inlet logistics at the compressor inlet logistics heat exchanger 323 for further cooling. The high-pressure gas-phase ethylene after cooling is sent to the first-stage tower reboiler 14, and is used as a heat source for heat exchange and condensation into liquid-phase ethylene, and then sent to the medium-pressure gas-liquid separation tank 33. The liquid at the bottom of the medium-pressure gas-liquid separation tank 33 is transported to the first-stage tower condenser 12 through the first pump 334, and is used as a cold source for heat exchange and evaporation into medium-pressure gas-phase ethylene. The medium-pressure gas-phase ethylene is then sent to the reboiler at the bottom of the secondary tower, and is used as a heat source for heat exchange and condensation into liquid-phase ethylene, and is sent to the low-pressure gas-liquid separation tank 34. The liquid at the bottom of the low-pressure gas-liquid separation tank 34 is transported to the second-stage tower condenser 22 through the second pump 344, and is used as a cold source for heat exchange and evaporation into low-pressure gas-phase ethylene. The low-pressure gas-phase ethylene is mixed with the top gas of the medium-pressure gas-liquid separation tank 33 and the top gas of the low-pressure gas-liquid separation tank 34, and then is heat exchanged with the high-pressure gas-phase ethylene at the outlet of the compressor 31 at the compressor inlet logistics heat exchanger 323, and then is sent to the inlet of the compressor 31 for pressurization and temperature increase.

[0103] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0104] The composition and flow rate of the raw gas phase used in the following examples and comparative examples are shown in Table 1.

[0105] Table 1 Composition and flow rate of raw gas phase

[0106] raw material <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> flow <![CDATA[BF3]]> 0.198 0.802 3.19kg / h

[0107] Example 1

[0108] The parameters of a device for separating boron isotopes by low-temperature distillation in this embodiment are as follows: the number of theoretical plates of the first-stage tower is 1500, and the operating pressure at the top of the tower is 631 kPa; the number of theoretical plates of the second-stage tower is 1000, and the operating pressure at the top of the tower is 201 kPa.

[0109] Here’s how to do it:

[0110] The purified BF3 raw material (3.19 kg / h, -98 ° C) is mixed with the liquid at the bottom of the second tower 20 (7.0 kg / h, -88 ° C) of the device 100 for separating boron isotopes by cryogenic distillation, and then sent to the feed low-temperature cold trap 40. After the cold trap is heated and pressurized (10.19 kg / h, -50 ° C, 700 kPa), it is sent to the first tower 10 for cryogenic distillation. High-purity and high-abundance boron isotope is obtained at the bottom of the first tower 10. 10 BF3 product (0.625kg / h). The vacuum jacket of the first-stage tower 10 is evacuated, and the vacuum degree is 0.3Pa (absolute pressure). The bottom temperature of the first-stage tower 10 is -68℃, the top temperature is -69℃, and the top pressure of the first-stage tower 10 is 0.63MPa. The top liquid of the first-stage tower 10 is sent to the second-stage tower 20 by self-pressure for low-temperature distillation, and the top of the second-stage tower 20 obtains high-purity and rich 11 The BF3 product (2.565 kg / h) and the second-stage tower 20 bottom liquid (7.0 kg / h, -88°C) are circulated and returned to the inlet of the feed low-temperature cold trap 40 to mix with the fresh raw material. The bottom temperature of the second-stage tower 20 is -88°C, the top temperature is -90°C, and the top pressure is 0.2 MPa.

[0111] The circulating refrigeration device 30 with ethylene as the circulating working fluid provides cooling and heat for the device. The ethylene (512kg / h, 96°C, 901kPa) after being pressurized and heated by the compressor 31 is cooled down (11°C) by the circulating water heat exchanger 321 and the chilled water heat exchanger 322, and then heat-exchanged with the compressor inlet logistics to further cool down (-55°C). The cooled high-pressure gas-phase ethylene is sent to the first-stage tower reboiler 14 (-57°C, load of 53kw), used as a heat source for heat exchange and condensation into liquid-phase ethylene, and sent to the medium-pressure gas-liquid separation tank 33. The liquid at the bottom of the medium-pressure gas-liquid separation tank 33 (448kg / h, -78°C, 369kPa) is transported to the first-stage tower condenser 12 (-78°C, load 53kw) via the first pump 334, and is used as a cold source for heat exchange and evaporation into medium-pressure gas-phase ethylene. The medium-pressure gas-phase ethylene is then sent to the second-stage tower reboiler 24 (-78°C, load 53kw), and is used as a heat source for heat exchange and condensation into liquid-phase ethylene, and is sent to the low-pressure gas-liquid separation tank 34. The liquid at the bottom of the low-pressure gas-liquid separation tank 34 (391kg / h, -103°C, 101kPa) is transported to the second-stage tower condenser 22 (-103°C, load of 53kw) through the second pump 344, and is used as a cold source for heat exchange and evaporation into low-pressure gas-phase ethylene. The low-pressure gas-phase ethylene is mixed with the top gas of the medium-pressure gas-liquid separation tank 33 and the top gas of the low-pressure gas-liquid separation tank 34 (512kg / h, -101°C, 101kPa) and heat-exchanged with the high-pressure gas-phase ethylene at the outlet of the compressor (1°C, 101kPa), and then sent to the compressor inlet for pressurization and temperature increase. The flow rate, pressure and temperature of the circulating ethylene match the device 100 for separating boron isotopes by low-temperature distillation, and meet the device operation requirements. The main energy consumption in the device is the power consumption of the ethylene compressor, which is about 37.5kw.

[0112] The product composition and flow rate of Example 1 are shown in Table 2.

[0113] Table 2 Product composition and flow rate of Example 1

[0114] product <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> flow <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> 0.9907 0.0093 0.625kg / h <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> 0.9980 0.002 2.565kg / h

[0115] Example 2

[0116] The parameters of a device for separating boron isotopes by low-temperature distillation in this embodiment are as follows: the number of theoretical plates of the first-stage tower is 1500, and the operating pressure at the top of the tower is 400 kPa; the number of theoretical plates of the second-stage tower is 1000, and the operating pressure at the top of the tower is 201 kPa.

[0117] Here’s how to do it:

[0118] The purified BF3 raw material (3.19 kg / h, -98 ° C) is mixed with the liquid at the bottom of the second tower 20 (7.0 kg / h, -88 ° C) of the device 100 for separating boron isotopes by cryogenic distillation, and then sent to the feed low-temperature cold trap 40. After the cold trap is heated and pressurized (10.19 kg / h, -50 ° C, 500 kPa), it is sent to the first tower 10 for cryogenic distillation. High-purity and high-abundance boron isotope is obtained at the bottom of the first tower 10. 10 BF3 product (0.625kg / h). The first stage tower 10 is evacuated by vacuum jacket, the vacuum degree is 0.3Pa (absolute pressure), the bottom temperature of the first stage tower 10 is -77℃, the top temperature is -78℃, and the top pressure is 0.40MPa. The top liquid of the first stage tower 10 is sent to the second stage tower 20 by self-pressure for low temperature distillation, and the top of the second stage tower 20 obtains high purity and abundance 11 The BF3 product (2.565 kg / h) and the second-stage tower 20 bottom liquid (7.0 kg / h, -88°C) are circulated and returned to the inlet of the feed low-temperature cold trap 40 to mix with the fresh raw material. The bottom temperature of the second-stage tower 20 is -88°C, the top temperature is -90°C, and the top pressure is 0.2 MPa.

[0119] The circulating refrigeration device 30 with ethylene as the circulating working fluid provides cooling and heat for the device. The ethylene (428kg / h, 84°C, 701kPa) after being pressurized and heated by the compressor 31 passes through the circulating water heat exchanger 321 and the chilled water heat exchanger 322 to be cooled (11°C), and then heat-exchanged with the compressor inlet logistics to be further cooled (-62°C). The cooled high-pressure gas-phase ethylene is sent to the first-stage tower reboiler 14 (-67°C, load of 47kw), used as a heat source for heat exchange and condensation into liquid-phase ethylene, and sent to the medium-pressure gas-liquid separation tank 33. The liquid at the bottom of the medium-pressure gas-liquid separation tank 33 (373kg / h, -83℃, 295kPa) is transported to the first-stage tower condenser 12 (-83℃, load 47kw) via the first pump 334, and is used as a cold source for heat exchange and evaporation to form medium-pressure gas-phase ethylene. The medium-pressure gas-phase ethylene is then sent to the second-stage tower reboiler 24 (-83℃, load 47kw), and is used as a heat source for heat exchange and condensation to form liquid-phase ethylene, and is sent to the low-pressure gas-liquid separation tank 34. The liquid at the bottom of the low-pressure gas-liquid separation tank 34 (348kg / h, -103°C, 101kPa) is transported to the second-stage tower condenser 22 (-103°C, load 47kw) via the second pump 344, and is used as a cold source for heat exchange and evaporation into low-pressure gas-phase ethylene. The low-pressure gas-phase ethylene is mixed with the gas at the top of the medium-pressure gas-liquid separation tank 33 and the gas at the top of the low-pressure gas-liquid separation tank 34 (428kg / h, -101°C, 101kPa), and is heat exchanged with the high-pressure gas-phase ethylene at the outlet of the compressor (1°C, 101kPa), and then sent to the compressor inlet for pressurization and temperature increase. The flow rate, pressure and temperature of the circulating ethylene match the device 100 for separating boron isotopes by low-temperature distillation, and meet the device operation requirements. The main energy consumption in the device is the power consumption of the ethylene compressor, which is about 27.5kw.

[0120] The product composition and flow rate of Example 2 are shown in Table 3. Comparing Example 1 with Example 2, it can be seen that the reduction of the pressure at the top of the first-stage tower can effectively reduce the power consumption of the ethylene compressor. However, the heat transfer temperature difference between the top condenser and the bottom reboiler of the first-stage tower and the second-stage tower is reduced, and the equipment investment is increased.

[0121] Table 3 Product composition and flow rate of Example 2

[0122] product <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> flow <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> 0.9908 0.0098 0.625kg / h <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> 0.9980 0.002 2.565kg / h

[0123] Example 3

[0124] The parameters of the device for separating boron isotopes by low-temperature distillation in this embodiment are as follows: the number of theoretical plates of the first-stage tower is 1500, and the operating pressure at the top of the tower is 600 kPa; the number of theoretical plates of the second-stage tower is 1000, and the operating pressure at the top of the tower is 401 kPa.

[0125] Here’s how to do it:

[0126] The purified BF3 raw material (3.19 kg / h, -98 ° C) is mixed with the liquid (7.0 kg / h, -88 ° C) of the second tower 20 of the device 100 for separating boron isotopes by cryogenic distillation, and then sent to the feed low-temperature cold trap 40. After the cold trap is heated and pressurized (10.19 kg / h, -50 ° C, 700 kPa), it is sent to the first tower 10 for cryogenic distillation. High-purity and abundant boron isotope is obtained at the bottom of the first tower 10. 10 BF3 product (0.625kg / h). The vacuum jacket of the first-stage tower 10 is evacuated, and the vacuum degree is 0.3Pa (absolute pressure). The bottom temperature of the first-stage tower 10 is -69℃, the top temperature is -70℃, and the top pressure is 0.60MPa. The top liquid of the first-stage tower 10 is sent to the second-stage tower 20 by self-pressure for low-temperature distillation. The top of the second-stage tower 20 obtains high-purity and rich 11 The BF3 product (2.565 kg / h) and the liquid at the bottom of the second tower 20 (7.0 kg / h, -77°C) are circulated and returned to the inlet of the feed low temperature cold trap 40 to mix with the fresh raw material. The bottom temperature of the second tower 20 is -77°C, the top temperature is -78°C, and the top pressure is 0.4 MPa.

[0127] The circulating refrigeration device 30 with ethylene as the circulating working fluid provides cooling and heat for the device. The ethylene (566kg / h, 70°C, 651kPa) after being pressurized and heated by the compressor 31 is cooled down (11°C) by the circulating water heat exchanger 321 and the chilled water heat exchanger 322, and then heat-exchanged with the compressor inlet logistics to further cool down (-64°C). The cooled high-pressure gas-phase ethylene is sent to the first-stage tower reboiler 14 (-64°C, load 64kw), used as a heat source for heat exchange and condensation into liquid-phase ethylene, and sent to the medium-pressure gas-liquid separation tank 33. The liquid at the bottom of the medium-pressure gas-liquid separation tank 33 (535kg / h, -73°C, 457kPa) is transported to the first-stage tower condenser 12 (-73°C, load 64kw) via the first pump 334, and is used as a cold source for heat exchange and evaporation into medium-pressure gas-phase ethylene. The medium-pressure gas-phase ethylene is then sent to the second-stage tower reboiler 24 (-73°C, load 64kw), and is used as a heat source for heat exchange and condensation into liquid-phase ethylene, and is sent to the low-pressure gas-liquid separation tank 34. The liquid at the bottom of the low-pressure gas-liquid separation tank 34 (505kg / h, -83°C, 295kPa) is transported to the second-stage tower condenser 22 (-83°C, load 64kw) via the second pump 344, and is used as a cold source for heat exchange and evaporation into low-pressure gas-phase ethylene. The low-pressure gas-phase ethylene is mixed with the gas at the top of the medium-pressure gas-liquid separation tank 33 and the gas at the top of the low-pressure gas-liquid separation tank 34 (566kg / h, -83°C, 295kPa), and is heat exchanged with the high-pressure gas-phase ethylene at the outlet of the compressor (6°C, 295kPa), and then sent to the compressor inlet for pressurization and temperature increase. The flow rate, pressure and temperature of the circulating ethylene match the device 100 for separating boron isotopes by low-temperature distillation, and meet the device operation requirements. The main energy consumption in the device is the power consumption of the ethylene compressor, which is about 15.5kw.

[0128] The product composition and flow rate of Example 3 are shown in Table 4. Comparing Example 1 with Example 3, it can be seen that the increase in the top pressure of the second-stage tower can effectively reduce the power consumption of the ethylene compressor. However, the heat transfer temperature difference between the top condenser and the bottom reboiler of the first-stage tower and the second-stage tower is reduced, and the equipment investment is increased.

[0129] Table 4 Product composition and flow rate of Example 3

[0130] product <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> flow <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> 0.9906 0.0094 0.625kg / h <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> 0.9980 0.002 2.565kg / h

[0131] Comparative Example 1

[0132] The parameters of the device for separating boron isotopes based on low-temperature distillation in this comparative example are as follows: the theoretical plate number of the first-stage tower is 1500, and the tower top operating pressure is 201 kPa; the theoretical plate number of the second-stage tower is 1000, and the tower top operating pressure is 201 kPa.

[0133] Here’s how to do it:

[0134] The purified BF3 raw material (3.19kg / h, -98℃) is mixed with the liquid at the bottom of the secondary tower of the BF3 cryogenic distillation device (2.5kg / h, -88℃) and sent to the feed cryogenic cold trap. After the cold trap is heated and pressurized (5.69kg / h, -50℃, 300kPa), it is sent to the primary tower for cryogenic distillation. High-purity and abundant BF3 is obtained at the bottom of the primary tower. 10 BF3 product (0.625kg / h). The vacuum jacket of the first tower well is evacuated, the vacuum degree is 0.3Pa (absolute pressure), the bottom temperature of the first tower is -88°C, the top temperature is -90°C, and the pressure at the top of the first tower is 0.20MPa. The liquid at the top of the first tower is sent to the second tower by self-pressure for low-temperature distillation, and the top of the second tower obtains high-purity and rich 11 BF3 product (2.565kg / h), secondary tower bottom liquid (2.5kg / h, -88°C) are circulated and returned to the inlet of the feed low temperature cold trap to mix with fresh raw materials. The temperature at the bottom of the secondary tower is -88°C, the temperature at the top of the tower is -90°C, and the pressure at the top of the secondary tower is 0.2MPa. The load of the reboiler and condenser at the bottom of the first tower is 34kw, and the load of the reboiler and condenser at the bottom of the second tower is 54kw. Comparative Example 1 uses liquid nitrogen as the cooling medium and electric heating at the bottom of the tower, which consumes 1.1t / h of liquid nitrogen and 88kw of electricity.

[0135] The product composition and flow rate of Comparative Example 1 are shown in Table 5. Comparing Example 1 with Comparative Example 1, it can be seen that there is no significant difference in the product composition and flow rate of the two. However, Comparative Example 1 uses liquid nitrogen as the cooling medium and electric heating is used at the bottom of the tower, which consumes 1.1t / h of liquid nitrogen and 88kw of electricity. Calculated based on liquid nitrogen of 800 yuan / t and electricity price of 0.66 yuan / kWh, the operating cost is 938.1 yuan / hour; the main energy consumption in the device in Example 1 is the power consumption of the ethylene compressor, which is about 37.5kw, and the operating cost is 24.8 yuan / hour. Compared with the liquid nitrogen cooling process in Comparative Example 1, the operating cost is reduced by 97.36%.

[0136] Table 5 Product composition and flow rate of comparative example 1

[0137] product <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> flow <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> 0.9905 0.0095 0.625kg / h <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> 0.9980 0.002 2.565kg / h

[0138] Comparative Example 2

[0139] The parameters of the device for separating boron isotopes based on low-temperature distillation in this comparative example are as follows: the theoretical plate number of the first-stage tower is 1500, and the tower top operating pressure is 201 kPa; the theoretical plate number of the second-stage tower is 1000, and the tower top operating pressure is 201 kPa.

[0140] Here’s how to do it:

[0141] The purified BF3 raw material (3.19kg / h, -98℃) is mixed with the liquid at the bottom of the secondary tower of the BF3 cryogenic distillation device (2.5kg / h, -88℃) and sent to the feed cryogenic cold trap. After the cold trap is heated and pressurized (5.69kg / h, -50℃, 300kPa), it is sent to the primary tower for cryogenic distillation. High-purity and abundant BF3 is obtained at the bottom of the primary tower. 10 BF3 product (0.625kg / h). The vacuum jacket of the first tower well is evacuated, the vacuum degree is 0.3Pa (absolute pressure), the bottom temperature of the first tower is -88℃, the top temperature is -90℃, and the pressure of the first tower top is 0.20MPa. The liquid at the top of the first tower is sent to the second tower by self-pressure for low-temperature distillation, and the top of the second tower obtains high-purity and rich 11 BF3 product (2.565kg / h), secondary tower bottom liquid (2.5kg / h, -88℃) are circulated and returned to the inlet of the feed low temperature cold trap to mix with fresh raw materials. The bottom temperature of the secondary tower distillation tower is -88℃, the top temperature is -90℃, and the secondary tower top pressure is 0.2MPa. The load of the reboiler and condenser at the bottom of the first tower is 34kw, and the load of the reboiler and condenser at the bottom of the second tower is 54kw. The refrigeration device using ethylene as the working fluid provides heat and cold for the low temperature distillation device at the same time. The main energy consumption in the device is the power consumption of the ethylene compressor, which is about 42.2kw.

[0142] The product composition and flow rate of Comparative Example 2 are shown in Table 6. Comparing Example 1 with Comparative Example 2, it can be seen that there is no significant difference in the product composition and flow rate of the two. However, in Comparative Example 2, the refrigeration device using ethylene as the working fluid has an ethylene compressor power consumption of 42.2kw and an operating cost of 27.9 yuan / hour. The main energy consumption in the device in Example 1 is the ethylene compressor power consumption, which is about 37.5kw, and the operating cost is 24.8 yuan / hour. Compared with the refrigeration device process using ethylene as the working fluid in Comparative Example 2, the operating cost is reduced by 11.1%.

[0143] Table 6 Product composition and flow rate of comparative example 2

[0144] product <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> flow <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> 0.9905 0.0095 0.625kg / h <h2 style=";text-align:left;direction:ltr"><![CDATA[ <h2 style=";text-align:left;direction:ltr"> 11 <h2 style=";text-align:left;direction:ltr"> BF3]]><h2 style=";text-align:left;direction:ltr"> 0.9980 0.002 2.565kg / h

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0146] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for separating boron isotopes by cryogenic distillation, characterized in that: include: The natural abundance BF3 raw material is introduced into the first stage tower for the first low temperature distillation to obtain the first tower top material and the first tower bottom material, wherein the first tower bottom material is a boron-10 abundance of not less than 99%. 10 BF3 products; The first tower top material enters the second tower for a second low temperature distillation to obtain a second tower top material and a second tower bottom material, wherein the second tower top material has a boron-11 abundance of not less than 99%. 11 BF3 product, the second tower bottom material is mixed with the BF3 raw material and then recycled; The top pressure of the first tower is 0.25 MPa to 0.65 MPa; the top pressure of the second tower is 0.1 MPa to 0.45 MPa; The first-stage tower and the second-stage tower use ethylene as a circulating medium to provide cold and heat.

2. The method for separating boron isotopes by cryogenic distillation according to claim 1, characterized in that: At least one of the following conditions is met: A. The bottom temperature and top temperature of the first-stage tower are -65°C to -85°C respectively; B. The bottom temperature and top temperature of the second stage tower are -75°C to -95°C respectively; C. The second tower bottom material is mixed with the BF3 raw material, and then heated and pressurized in a cold trap and then introduced into the first tower; D. When condition C is met, the temperature of the second bottom material after mixing with the BF3 raw material and heating and pressurizing in the cold trap is -65°C to 40°C, and the pressure is 0.25MPa to 1.5MPa; E. The environmental vacuum degree of the first stage tower is 0.0001Pa~10Pa.

3. The method for separating boron isotopes by cryogenic distillation according to claim 1 or 2, characterized in that: The first stage tower and the second stage tower use ethylene as the circulating medium to provide cold and heat including: The ethylene is pressurized and heated by a compressor, then cooled by a heat exchanger and cooled by heat exchange with the compressor inlet stream to obtain high-pressure gas-phase ethylene, and the high-pressure gas-phase ethylene is transported to the bottom reboiler of the first-stage tower as a heat source, and condensed into a first liquid-phase ethylene by heat exchange; The first liquid phase ethylene is subjected to medium-pressure gas-liquid separation to obtain medium-pressure liquid phase ethylene and first gas phase ethylene, and the medium-pressure liquid phase ethylene is transported to the top condenser of the first-stage tower as a cold source, and evaporated into medium-pressure gas phase ethylene by heat exchange; The medium-pressure gas phase ethylene is transported to the bottom reboiler of the second-stage tower as a heat source, and condensed into second liquid phase ethylene by heat exchange; The second liquid phase ethylene is subjected to low-pressure gas-liquid separation to obtain low-pressure liquid phase ethylene and second gas phase ethylene, and the low-pressure liquid phase ethylene is transported to the top condenser of the second tower as a cold source, and evaporated into low-pressure gas phase ethylene by heat exchange; The low-pressure gas-phase ethylene is mixed with the first gas-phase ethylene and the second gas-phase ethylene to obtain the compressor inlet logistics.

4. The method for separating boron isotopes by cryogenic distillation according to claim 3, characterized in that: At least one of the following conditions is met: A. The temperature of ethylene after being pressurized and heated by a compressor is 40℃~160℃ and the pressure is 0.3MPa~1.5MPa; B. The temperature after cooling by the heat exchanger is 40°C to 160°C; C. The temperature after heat exchange and cooling with the compressor inlet logistics is -70℃~-30℃; D. The temperature of the medium-pressure liquid phase ethylene is -57°C to -93°C, and the pressure is 0.15MPa to 1.0MPa; E. The temperature of the low-pressure liquid phase ethylene is -67°C to -103°C, and the pressure is 0.1MPa to 0.7MPa; F. The temperature of the compressor inlet logistics is -30℃~30℃, and the pressure is 0.1MPa~0.7MPa.

5. A device for separating boron isotopes by cryogenic distillation, used for carrying out the method for separating boron isotopes by cryogenic distillation according to any one of claims 1 to 4, characterized in that: include: First stage tower, second stage tower and circulating refrigeration device; The first stage tower is provided with a feed inlet in the tower and a 10 The BF3 product extraction port, the top of the first-stage tower is connected to the middle of the second-stage tower, and the top of the second-stage tower is provided with 11 BF3 product extraction port, the bottom of the second-stage tower is connected to the feed port; The first-stage tower comprises a first-stage tower condenser arranged at the top of the tower and a first-stage tower reboiler arranged at the bottom of the tower; the second-stage tower comprises a second-stage tower condenser arranged at the top of the tower and a second-stage tower reboiler arranged at the bottom of the tower; The circulating refrigeration device is connected with the first-stage tower condenser, the first-stage tower reboiler, the second-stage tower condenser, and the second-stage tower reboiler.

6. The device for separating boron isotopes by cryogenic distillation according to claim 5, characterized in that: The circulating refrigeration device comprises: a compressor, a heat exchanger, a medium-pressure gas-liquid separation tank and a low-pressure gas-liquid separation tank; The outlet of the compressor is connected to the heat exchanger, and the inlet of the compressor is connected to the medium-pressure gas-liquid separation tank, the low-pressure gas-liquid separation tank and the second-stage tower condenser; The heat exchanger is connected to the first-stage tower reboiler, the medium-pressure gas-liquid separation tank is connected to the first-stage tower condenser and the first-stage tower reboiler, the low-pressure gas-liquid separation tank is connected to the second-stage tower condenser and the second-stage tower reboiler, and the first-stage tower condenser is connected to the second-stage tower reboiler.

7. The device for separating boron isotopes by cryogenic distillation according to claim 6, characterized in that: The heat exchanger comprises: a circulating water heat exchanger, a chilled water heat exchanger and a compressor inlet logistics heat exchanger, wherein the circulating water heat exchanger is connected to the outlet of the compressor, the chilled water heat exchanger is connected to the circulating water heat exchanger, and the compressor inlet logistics heat exchanger is connected to the chilled water heat exchanger and the first-stage tower reboiler; The inlet of the compressor is connected to the medium-pressure gas-liquid separation tank, the low-pressure gas-liquid separation tank and the second-stage tower condenser through the compressor inlet logistics heat exchanger.

8. The device for separating boron isotopes by cryogenic distillation according to claim 6, characterized in that: The medium-pressure gas-liquid separation tank includes: a first inlet, a first tank top outlet, and a first tank bottom outlet; the first-stage tower reboiler is connected to the first inlet, the first tank top outlet is connected to the compressor inlet, and the first tank bottom outlet is connected to the first-stage tower condenser through a first pump.

9. The device for separating boron isotopes by cryogenic distillation according to claim 6, characterized in that: The low-pressure gas-liquid separation tank includes: a second inlet, a second tank top outlet, and a second tank bottom outlet; the second-stage tower reboiler is connected to the second inlet, the second tank top outlet is connected to the compressor inlet, and the second tank bottom outlet is connected to the second-stage tower condenser through a second pump.

10. The device for separating boron isotopes by cryogenic distillation according to claim 5, characterized in that: The device for separating boron isotopes by cryogenic distillation further comprises at least one of the following structures: A. a feed low temperature cold trap, wherein the feed low temperature cold trap is connected to the feed port; B. an aluminum polyester film, the aluminum polyester film being wrapped around the surface of the first-stage tower and the second-stage tower; C. a tower well vacuum jacket, arranged around the first-stage tower; D. When condition C is satisfied, it further comprises an outer jacket, which is arranged outside the vacuum jacket of the tower well.

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