Method and system for separating hydrogen isotopes with low energy consumption

Abstract

The invention provides a low-energy-consumption hydrogen isotope separation method and system, and relates to the technical field of hydrogen isotope enrichment. The method comprises the following steps: sequentially carrying out multi-stage rectification on a liquid ammonia raw material to obtain rectified liquid ammonia and a hydrogen isotope compound; the hydrogen isotope compound comprises ND3; a heat source for rectification comprises industrial waste heat. Compared with a conventional method for preparing the isotope from water, the method has the advantages that the liquid ammonia is selected as the raw material based on the reasons of large separation factor, appropriate operation temperature, stable raw material, no corrosion and the like of the liquid ammonia, the hydrogen isotope compound is prepared through multi-stage rectification, and the method is simple to operate, low in investment, high in production capacity, high in product yield and good in economical efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of hydrogen isotope enrichment, and in particular to a method and system for separating hydrogen isotopes with low energy consumption. Background Art

[0002] There are three isotopes of hydrogen: protium H, deuterium D, and tritium T, of which tritium is radioactive. Hydrogen isotopes are widely used in the fields of medicine, nuclear energy, and national defense. For example, in medical research, deuterium-substituted drugs can improve the efficacy and duration of drug action by using the principle that deuterium slows down metabolism; in heavy water nuclear reactors that generate nuclear fission energy, heavy water is used as a moderator and coolant; in fusion reactors, which are considered to be the ultimate energy source for mankind, energy is mainly generated by deuterium and tritium nuclear fusion reactions; in the field of national defense, deuterium and tritium are important materials for nuclear weapons (hydrogen bombs). In addition, in academic research, deuterium and tritium are also tracer elements that track the participation of hydrogen in certain physical and chemical processes. However, the relative abundance of hydrogen isotopes D and T in nature is extremely low, with a relative abundance of D of about 0.0156% and a relative abundance of T of less than 0.001%.

[0003] There are many methods for enriching hydrogen isotopes, such as distillation, membrane distillation, dual-temperature exchange, electrolysis, etc. Distillation is the earliest method for separating heavy water by using the slight difference in saturated vapor pressure between isotope atoms or molecules. 2 O / HDO) and hydrogen sulfide (H 2 The difference in the hydrogen isotope exchange reaction rate between S / HDS) with temperature changes, but the energy cost of this method is high, and the hydrogen sulfide process faces problems such as corrosion and wastewater discharge. The study found that NH 3 / NH 2 The D separation factor is 1.04 under normal pressure. As a separation material, it has the advantages of large separation factor, stable raw materials, and non-corrosiveness. It is simpler to achieve large-scale industrial production. The energy consumption of ammonia distillation (heat pump method) is 3500kwh / kg, that is, the energy consumption of producing 1 kilogram of heavy water is 3500 kWh. How to further reduce the energy consumption of the system has become a research focus.

[0004] In the process of industrial production, a large amount of thermal energy is often dissipated into the environment in the form of waste heat, resulting in a huge waste of energy. Taking the petrochemical industry as an example, after the circulating cooling water cools the process logistics, the heat is discharged into the environment through the cooling tower. At present, the waste heat utilization of circulating water is mainly achieved through heat pump technology, which converts low-grade waste heat or waste heat into high-grade thermal energy, thereby realizing heating of the surrounding areas. Therefore, how to effectively utilize industrial waste heat (such as circulating cooling water) has also become a research focus. Summary of the invention

[0005] The purpose of this application is to provide a method and system for separating hydrogen isotopes with low energy consumption to solve the above-mentioned problems.

[0006] To achieve the above objectives, the first aspect of the present application provides a method for separating hydrogen isotopes with low energy consumption, comprising:

[0007] The liquid ammonia raw material is sequentially subjected to multi-stage distillation to obtain distilled liquid ammonia and hydrogen isotope compounds;

[0008] The hydrogen isotope compound includes ND 3 ;

[0009] The heat source for the distillation includes industrial waste heat.

[0010] Optionally, the purity of the liquid ammonia raw material is greater than or equal to 99.5%.

[0011] Optionally, the ND 3 The abundance is 98%-99.9%.

[0012] Optionally, the method for separating hydrogen isotopes with low energy consumption satisfies at least one of the following conditions:

[0013] A. The temperature for gathering the hydrogen isotope compound is 10°C-60°C;

[0014] B. Aggregation The temperature of the liquid ammonia after distillation is 9°C-60°C, and the pressure is 0.5MPa-2.6MPa.

[0015] Optionally, the temperature at which the distilled liquid ammonia is gathered is lower than the temperature at which the hydrogen isotope compound is gathered.

[0016] Optionally, the multi-stage distillation includes a first distillation, a second distillation, a third distillation, a fourth distillation and a fifth distillation performed sequentially;

[0017] The liquid ammonia raw material is subjected to the first distillation to obtain liquid ammonia after the first distillation and a first hydrogen isotope compound. The first hydrogen isotope compound is subjected to the second distillation to obtain liquid ammonia after the second distillation and a second hydrogen isotope compound. The second hydrogen isotope compound is subjected to the third distillation to obtain liquid ammonia after the third distillation and a third hydrogen isotope compound. The third hydrogen isotope compound is subjected to the fourth distillation to obtain liquid ammonia after the fourth distillation and a fourth hydrogen isotope compound. The fourth hydrogen isotope compound is subjected to the fifth distillation to obtain the distilled liquid ammonia and the hydrogen isotope compound.

[0018] Optionally, the second distilled liquid ammonia, the third distilled liquid ammonia, the fourth distilled liquid ammonia, and the distilled liquid ammonia are each independently returned to the previous stage of distillation treatment.

[0019] A second aspect of the present application provides a system for separating hydrogen isotopes with low energy consumption, comprising multiple stages of distillation devices connected in sequence.

[0020] Optionally, the multi-stage distillation device includes a first distillation device, a second distillation device, a third distillation device, a fourth distillation device, and a fifth distillation device connected in sequence;

[0021] The first distillation device, the second distillation device, the third distillation device, the fourth distillation device and the fifth distillation device each independently include a distillation tower, a reboiler, a condenser, a separator tank, a reflux pump, and a feed pump.

[0022] Optionally, the distillation tower has a theoretical plate number of 200-400.

[0023] Compared with the prior art, the beneficial effects of this application include:

[0024] The low-energy method for separating hydrogen isotopes provided in the present application is compared with the conventional method of preparing isotopes using water. Based on the reasons that liquid ammonia has a large separation factor, suitable operating temperature, stable raw materials, and is non-corrosive, the present application selects liquid ammonia as the raw material and prepares hydrogen isotope compounds through multi-stage distillation. The method has low investment, simple operation, large production capacity, high product yield, and good economy.

[0025] The low-energy system for separating hydrogen isotopes provided in the present application constructs a liquid ammonia distillation device using industrial waste heat as a heat source to achieve hydrogen isotope separation. At the same time, the system energy consumption is greatly reduced, and there are no problems such as corrosion and wastewater discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 Schematic diagram of the system for low-energy separation of hydrogen isotopes provided in this application. DETAILED DESCRIPTION

[0028] As used herein:

[0029] "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.

[0030] 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.

[0031] 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.

[0032] In these examples, parts and percentages are by mass unless otherwise indicated.

[0033] "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.

[0034] "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).

[0035] At present, the main industrial method for producing heavy water in the world is the GS dual-temperature hydrogen sulfide exchange method, which relies on water (H 2 O / HDO) and hydrogen sulfide (H 2 The difference in the hydrogen isotope exchange reaction rate between S / HDS) with temperature changes, but the energy cost of this method is high, and the hydrogen sulfide process faces problems such as corrosion and wastewater discharge. The study found that NH 3 / NH 2The D separation factor is 1.04 at normal pressure. As a separation material, it has the advantages of large separation factor, stable raw materials, and non-corrosiveness, which makes it easier to achieve large-scale industrial production. The energy consumption of ammonia distillation (heat pump method) is 3500kwh / kg, that is, the energy consumption of producing 1 kg of heavy water is 3500 kWh, which is lower than the GS dual-temperature hydrogen sulfide exchange method. However, since the GS dual-temperature hydrogen sulfide exchange method is currently the mainstream solution, although the energy consumption is lower than the GS dual-temperature hydrogen sulfide exchange method, if industrial waste heat is not used, considering the comprehensive energy consumption, investment and technical maturity, the energy consumption of ammonia distillation (heat pump method) is not considered by capital.

[0036] Based on this, the first aspect of the present application provides a method for separating hydrogen isotopes with low energy consumption, comprising:

[0037] The liquid ammonia raw material is sequentially subjected to multi-stage distillation to obtain distilled liquid ammonia and hydrogen isotope compounds;

[0038] The hydrogen isotope compound includes ND 3 ;

[0039] It should be noted that due to the continuous enrichment of deuterium isotopes (D), an isotope exchange reaction will occur, and the reaction formula is:

[0040] Formula 1: 2NH 2 D→NH 3 +NHD 2 ;

[0041] Formula 2: 2NHD 2 →ND 3 +NH 2 D;

[0042] The equilibrium constant of formula 1 at 25°C is 2.94, and the equilibrium constant of formula 2 at 25°C is 2.9. The equilibrium time is long enough to finally obtain high-abundance ND 3 product;

[0043] Among them, isotope exchange is the process of isotope redistribution in the system. When the physical and chemical states of the system do not change, isotope exchange occurs between different molecules, within the same molecule and between different phases, and between the same atoms or isotope atoms. Isotope exchange reactions are reversible, and like general chemical reactions, the extent of the reaction can be expressed by the equilibrium constant. This is an equimolecular reaction, and the chemical components do not change before and after the reaction. Only the concentration of isotopes is redistributed among the chemical components. Therefore, in the first to fifth towers, in the multi-stage distillation process, NH 3 NH 2 D. NHD 2 ND 3 The concentration changes, and thus the isotope exchange reaction occurs accordingly;

[0044] The heat source for the distillation includes industrial waste heat.

[0045] It should be noted that industrial waste heat can become a heat source for distillation, which can achieve effective energy utilization and further reduce energy consumption. Industrial waste heat refers to solid, liquid or gaseous substances that carry heat generated in industrial production. For example, industrial waste heat includes but is not limited to process logistics, steam, hot water, circulating water and other heat sources.

[0046] In some embodiments, the purity of the liquid ammonia raw material is greater than or equal to 99.5%.

[0047] Optionally, the purity of the liquid ammonia raw material may be 99.5%, 99.9%, 99.99%, 99.999% or any value greater than or equal to 99.5%.

[0048] In some embodiments, the ND 3 The abundance is 98%-99.9%.

[0049] Optional, ND 3 The abundance can be 98%, 99%, 99.9% or any value between 98% and 99.9%.

[0050] In some embodiments, the method for separating hydrogen isotopes with low energy consumption satisfies at least one of the following conditions:

[0051] A. The temperature for gathering the hydrogen isotope compound is 10°C-60°C;

[0052] Optionally, the temperature of the aggregated hydrogen isotope compound may be 10°C, 20°C, 30°C, 40°C, 50°C, 60°C or any value between 10°C and 60°C;

[0053] B. Aggregation The temperature of the liquid ammonia after distillation is 9°C-60°C, and the pressure is 0.5MPa-2.6MPa.

[0054] Optionally, the temperature of the liquid ammonia after aggregation and distillation can be 9°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C or any value between 9°C and 60°C, and the pressure can be 0.5MPa, 1MPa, 1.5MPa, 2.6MPa or any value between 0.5MPa and 2.6MPa.

[0055] In some embodiments, the temperature at which the distilled liquid ammonia is accumulated is lower than the temperature at which the hydrogen isotope compound is accumulated.

[0056] In some embodiments, the multi-stage distillation includes a first distillation, a second distillation, a third distillation, a fourth distillation, and a fifth distillation performed sequentially;

[0057] The liquid ammonia raw material is subjected to the first distillation to obtain liquid ammonia after the first distillation and a first hydrogen isotope compound. The first hydrogen isotope compound is subjected to the second distillation to obtain liquid ammonia after the second distillation and a second hydrogen isotope compound. The second hydrogen isotope compound is subjected to the third distillation to obtain liquid ammonia after the third distillation and a third hydrogen isotope compound. The third hydrogen isotope compound is subjected to the fourth distillation to obtain liquid ammonia after the fourth distillation and a fourth hydrogen isotope compound. The fourth hydrogen isotope compound is subjected to the fifth distillation to obtain the distilled liquid ammonia and the hydrogen isotope compound.

[0058] It should be noted that the low-energy method for separating hydrogen isotopes provided in this application is achieved by matching the logistics of industrial waste heat and the flow rate, pressure and temperature of the cooling medium with the liquid ammonia distillation device.

[0059] In some embodiments, the second distilled liquid ammonia, the third distilled liquid ammonia, the fourth distilled liquid ammonia, and the distilled liquid ammonia are each independently returned to the previous distillation process.

[0060] A second aspect of the present application provides a system for separating hydrogen isotopes with low energy consumption, comprising multiple stages of distillation devices connected in sequence.

[0061] In some embodiments, Figure 1 As shown, the multi-stage distillation device includes a first distillation device 100, a second distillation device 200, a third distillation device 300, a fourth distillation device 400, and a fifth distillation device 500 which are connected in sequence;

[0062] Exemplarily, the first distillation device 100 includes a distillation tower 110, a reboiler 120, a condenser 130, a separator 140, a reflux pump 150, and a feed pump 160;

[0063] The distillation tower 110 includes a first inlet, a second inlet, a third inlet, a fourth inlet, a first outlet, and a second outlet;

[0064] The first inlet is used to feed liquid ammonia to be distilled;

[0065] The first outlet is provided at the bottom of the distillation tower 110, and is used to transport the product obtained after the distillation. It should be noted that the first outlet is also connected to the inlet of the reboiler 120, and the outlet of the reboiler 120 is connected to the second inlet, and is used to provide heat when the distillation tower is working;

[0066] The second outlet is provided at the top of the distillation tower 110, and is connected to the condenser 130, the liquid separator 140 and the reflux pump 150 in sequence. The outlet of the reflux pump 150 is connected to the third inlet of the distillation tower 110 to form a circulation of the cooling medium. It should be noted that the outlet of the reflux pump 150 is also used to discharge the liquid nitrogen out of the first distillation device 100;

[0067] The fourth inlet is connected to the first outlet of the reflux pump 250 and is used to return the distilled liquid ammonia to the distillation tower 110 for processing.

[0068] The second distillation device 200 includes a distillation tower 210, a reboiler 220, a condenser 230, a liquid separator 240, a reflux pump 250, and a feed pump 260;

[0069] The third distillation device 300 includes a distillation tower 310, a reboiler 320, a condenser 330, a liquid separator 340, a reflux pump 350, and a feed pump 360;

[0070] The fourth distillation device 400 includes a distillation tower 410, a reboiler 420, a condenser 430, a liquid separator 440, a reflux pump 450, and a feed pump 460;

[0071] The fifth distillation device 500 includes a distillation tower 510, a reboiler 520, a condenser 530, a liquid separator 540, and a reflux pump 550;

[0072] The second distillation device 200, the third distillation device 300, the fourth distillation device 400, the fifth distillation device 500 are similar in structure to the first distillation device 100;

[0073] Among them, a feed pump is set at the inlet and outlet between each distillation device to transport the bottom distillation product to the next distillation tower for processing. In some embodiments, the fifth distillation device 500 is the last stage distillation device, and the first outlet of the distillation tower 510 directly outputs the distillation product, and a pump is not required.

[0074] In some embodiments, the distillation tower has a theoretical plate number of 200-400.

[0075] Optionally, the number of theoretical plates of the distillation tower can be 200, 250, 300, 400 or any integer between 200-400.

[0076] It should be noted that the setting of the distillation tower is mainly based on the heat grade provided by industrial waste heat. The operating parameters of the distillation tower are designed through parameters such as the temperature of conventional industrial waste heat. The basic principle is to make good use of industrial waste heat and achieve low energy consumption.

[0077] It should also be noted that the large number of theoretical plates required for isotopic enrichment of liquid ammonia results in the tower being too tall, so tower cascade technology is used to effectively reduce the height of each distillation tower by increasing the tower diameter.

[0078] 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.

[0079] The gas phase composition and feed flow rate of the liquid ammonia raw material used in the examples and comparative examples are specifically shown in Table 1.

[0080] Table 1 Liquid ammonia raw materials

[0081]

[0082] Example 1

[0083] This embodiment provides a method for separating hydrogen isotopes with low energy consumption, which specifically includes:

[0084] S1: Liquid ammonia raw material (49.5℃ 125kg / h) is sent to the first-stage tower for distillation. The top of the first-stage tower produces liquid ammonia product (NH 2 D accounts for 0.0305%, 124.992kg / h), and low-abundance NH 2 D product (NH 2 D accounts for 0.296%, ND 3 Proportion: 2.46×10 -9 %), the bottom temperature of the first-stage distillation tower is 20°C, the top temperature is 18°C, and the top pressure of the first-stage tower is 0.8MPa;

[0085] S2: The liquid at the bottom of the first tower is pumped to the top of the second tower for distillation, and a higher abundance of NH 2 D product (NH 2 D accounts for 1.38%, ND 3 Proportion: 1.07×10 -8 %), secondary tower top liquid (NH 2 D accounts for 0.232%) and is returned to the bottom inlet of the first-stage distillation tower. The bottom temperature of the second-stage distillation tower is 20°C, the top temperature is 18°C, and the top pressure of the second-stage tower is 0.8MPa;

[0086] S3: The liquid at the bottom of the secondary tower is pumped to the top of the tertiary tower for distillation, and a higher abundance of NH 2 D product (NH2 D℃ accounts for 4.88%, ND 3 Proportion: 1.77×10 -7 %), liquid at the top of the third tower (NH 2 D accounts for 1.16%) and is sent back to the bottom entrance of the secondary tower. The bottom temperature of the tertiary tower is 20°C, the top temperature is 18°C, and the top pressure of the tertiary tower is 0.8MPa;

[0087] S4: The liquid at the bottom of the third tower is pumped to the top of the fourth tower for distillation, and a higher abundance of NH 2 D product (NH 2 D accounts for 9.97%, ND 3 0.33%), the top liquid of the fourth tower (NH 2 D accounts for 1.77%) and is returned to the bottom entrance of the third-stage distillation tower. The bottom temperature of the fourth-stage distillation tower is 20°C, the top temperature is 18°C, and the top pressure of the fourth-stage tower is 0.8MPa;

[0088] S5: The liquid at the bottom of the fourth tower is pumped to the top of the fifth tower for distillation, and high-abundance ND is obtained at the bottom of the fifth tower. 3 Products (ND 3 99.9%, 8g / h), five-stage tower top liquid (NH 2 D accounts for 4.94%) and is sent back to the bottom entrance of the fourth-stage distillation tower. The bottom temperature of the fifth-stage distillation tower is 22°C, the top temperature is 18°C, and the top pressure of the fifth-stage tower is 0.8MPa.

[0089] This embodiment uses industrial circulating water to provide heat source for the system. The reboiler of the liquid ammonia distillation system needs to provide a total of 1112kw of heat. The circulating water supply temperature is cooled from 32°C to 28°C, and the circulating water supply flow rate is 240t / h.

[0090] Since the tower top temperature is 18°C, the distillation tower top cooler is provided with cooling capacity by logistics such as chilled water. The chilled water temperature is raised from 7°C to 12°C, and the chilled water flow rate is 192t / h.

[0091] Example 2

[0092] The difference from Example 1 is that the heat source is negative pressure steam (12 kPa, 50°C), the system reboiler needs to provide a total of 1112 kW of heat, the negative pressure steam is cooled from 50°C to 28°C and becomes liquid, and the negative pressure steam flow rate is 1.6 t / h.

[0093] Example 3

[0094] The difference from Example 1 is that the heat source is hot water (80°C), the system reboiler needs to provide a total of 1112kw of heat, the hot water is cooled from 80°C to 50°C and becomes liquid, and the hot water flow rate is 32t / h.

[0095] Example 4

[0096] This embodiment provides a method for separating hydrogen isotopes with low energy consumption, which specifically includes:

[0097] S1: Liquid ammonia raw material with a purity of 99.5% (49.5℃ 125kg / h) is sent to a primary distillation tower for distillation. The top of the primary distillation tower produces a liquid ammonia product (NH 2 D accounts for 0.0353%), and the bottom of the primary distillation tower obtains low-abundance NH 2 D product (NH 2 D accounts for 0.279%, ND 3 Proportion: 2.44×10 -9 %), the bottom temperature of the primary distillation tower is 42.5°C, the top temperature is 41.2°C, and the top pressure is 1.6MPa;

[0098] S2: The bottom liquid of the primary distillation tower is pumped to the secondary distillation tower for distillation. The bottom of the secondary distillation tower obtains a higher abundance of NH 2 D product (NH 2 D accounts for 1.33%, ND 3 Proportion X1.56×10 -7 %)), the top liquid of the secondary distillation tower (NH 2 D accounts for 0.234% and is returned to the primary distillation tower. The bottom temperature of the secondary distillation tower is 42.5°C, the top temperature is 41.2°C, and the top pressure of the secondary tower is 1.6MPa.

[0099] S3: The bottom liquid of the secondary distillation tower is pumped to the tertiary distillation tower for distillation. The bottom of the tertiary distillation tower obtains a higher abundance of NH 2 D product (NH 2 D accounts for 5.90%, ND 3 Proportion: 6.15×10 -5 %), the top liquid of the three-stage distillation tower (NH 2 D accounts for 1.17%) and is sent back to the secondary distillation tower. The bottom temperature of the tertiary distillation tower is 42.5°C, the top temperature is 41.2°C, and the top pressure of the tertiary tower is 1.6MPa.

[0100] S4: The bottom liquid of the three-stage distillation tower is pumped to the four-stage three-stage distillation tower for distillation. The bottom of the four-stage distillation tower obtains a higher abundance of NH 2 D product (NH 2D accounts for 14.2%, ND 3 The top liquid of the four-stage distillation tower (NH 2 D accounts for 3.72%) and is sent back to the three-stage distillation tower. The bottom temperature of the four-stage distillation tower is 42.5°C, the top temperature is 41.2°C, and the top pressure of the four-stage distillation tower is 1.6MPa;

[0101] S5: The bottom liquid of the four-stage distillation tower is pumped to the five-stage distillation tower for distillation. The bottom of the five-stage distillation tower is used to obtain high-abundance ND 3 Products (ND 3 99.9%, 6g / h), the top liquid of the five-stage distillation tower (NH 2 D accounts for 10.3%) and is returned to the fourth-stage tower for distillation. The bottom temperature of the fifth-stage distillation tower is 44.0°C, the top temperature is 41.2°C, and the top pressure is 1.6MPa.

[0102] This embodiment uses negative pressure steam (20kPa, 60°C) to provide a heat source for the system. The system reboiler needs to provide a total of 1112kw of heat. The temperature of the negative pressure steam drops from 60°C to 50°C and turns into a liquid phase. The flow rate of the negative pressure steam is 1.7t / h.

[0103] Since the tower top temperature is 41°C, the tower top cooler is provided with cooling capacity by circulating water and other logistics. The circulating water temperature is raised from 32°C to 37°C, and the circulating water flow rate is 192t / h.

[0104] Example 5

[0105] The difference from Example 4 is that the hot water temperature is cooled from 90° C. to 70° C., and the hot water flow rate is 48 t / h.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 4 is that a heat pump process is used to provide a heat source for the liquid ammonia distillation method. The gas phase at the top of each distillation tower is compressed and used as a reboiler heat source. After cooling, it returns to the top of each tower. The total power consumption of the compressor is 33kw.

[0108] Comparing Example 4 with Comparative Example 1, it can be seen that there is no difference in product composition and flow rate between the two, but the operation cost of Comparative Example 1 is 21.8 yuan / hour based on the electricity price of 0.66 yuan / kWh; the main energy consumption in the device in Example 4 is negative pressure steam, but because it is industrial waste heat, it has little application value. Compared with the heat pump process in Comparative Example 1, the operation cost and difficulty are greatly reduced. Since there is no need to invest in heat pump compressor equipment, the initial investment is reduced.

[0109] Comparative Example 2

[0110] The difference between this comparative example and Example 1 is that the bottom temperature of the distillation tower is 4.1°C.

[0111] Obtained ND 3 The purity of the product is 99.9%, but the product flow rate is 10 g / h.

[0112] Comparative Example 3

[0113] The difference between this comparative example and Example 1 is that the bottom temperature of the distillation tower is 65°C.

[0114] Obtained ND 3 The purity of the product was 26.5%.

[0115] analyze:

[0116] From the above experiments, we can know that the lower the bottom temperature of the distillation tower, the greater the separation factor. Under the condition of the same product purity, the product flow rate increases and the production capacity increases. However, the corresponding top temperature also decreases, and the cooling capacity of the top condenser needs to consume more energy. The higher the bottom temperature of the distillation tower, under the condition of the same product flow rate, the product purity decreases and cannot meet the market demand. The bottom reboiler needs to consume higher energy levels of heat.

[0117] 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.

[0118] 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 hydrogen isotopes with low energy consumption, characterized in that: include: The liquid ammonia raw material is sequentially subjected to multi-stage distillation to obtain distilled liquid ammonia and hydrogen isotope compounds; The hydrogen isotope compound includes ND3; The heat source for the distillation includes industrial waste heat.

2. The method for separating hydrogen isotopes with low energy consumption according to claim 1, characterized in that: The purity of the liquid ammonia raw material is greater than or equal to 99.5%.

3. The method for separating hydrogen isotopes with low energy consumption according to claim 1, characterized in that: The abundance of ND3 is 98%-99.9%.

4. The method for separating hydrogen isotopes with low energy consumption according to claim 1, characterized in that: At least one of the following conditions is met: A. The temperature for gathering the hydrogen isotope compound is 10°C-60°C; B. Aggregation The temperature of the liquid ammonia after distillation is 9°C-60°C, and the pressure is 0.5MPa-2.6MPa.

5. The method for separating hydrogen isotopes with low energy consumption according to claim 4, characterized in that: The temperature at which the distilled liquid ammonia is gathered is lower than the temperature at which the hydrogen isotope compound is gathered.

6. The method for separating hydrogen isotopes with low energy consumption according to any one of claims 1 to 5, characterized in that: The multi-stage distillation includes a first distillation, a second distillation, a third distillation, a fourth distillation and a fifth distillation performed in sequence; The liquid ammonia raw material is subjected to the first distillation to obtain liquid ammonia after the first distillation and a first hydrogen isotope compound. The first hydrogen isotope compound is subjected to the second distillation to obtain liquid ammonia after the second distillation and a second hydrogen isotope compound. The second hydrogen isotope compound is subjected to the third distillation to obtain liquid ammonia after the third distillation and a third hydrogen isotope compound. The third hydrogen isotope compound is subjected to the fourth distillation to obtain liquid ammonia after the fourth distillation and a fourth hydrogen isotope compound. The fourth hydrogen isotope compound is subjected to the fifth distillation to obtain the distilled liquid ammonia and the hydrogen isotope compound.

7. The method for separating hydrogen isotopes with low energy consumption according to claim 6, characterized in that: The second distilled liquid ammonia, the third distilled liquid ammonia, the fourth distilled liquid ammonia, and the distilled liquid ammonia are independently returned to the previous stage of distillation.

8. A system for separating hydrogen isotopes with low energy consumption, characterized in that: It includes multiple-stage distillation devices connected in sequence.

9. The system for separating hydrogen isotopes with low energy consumption according to claim 8, characterized in that: The multi-stage distillation device comprises a first distillation device, a second distillation device, a third distillation device, a fourth distillation device, and a fifth distillation device connected in sequence; The first distillation device, the second distillation device, the third distillation device, the fourth distillation device and the fifth distillation device each independently include a distillation tower, a reboiler, a condenser, a separator tank, a reflux pump, and a feed pump.

10. The system for separating hydrogen isotopes with low energy consumption according to claim 9, characterized in that: The number of theoretical plates of the distillation tower is 200-400.

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