Distillation method deuterium-depleted water production system and production method based on nitrogen gas stripping

Abstract

The invention provides a system and a method for producing deuterium-depleted water by a distillation method based on nitrogen gas stripping. The system comprises a pretreatment unit, a gas stripping distillation unit and a product collection unit which are connected in sequence, the pretreatment unit comprises a raw water tank, a multi-stage filter and an electrodeionization device which are sequentially connected along the material flow direction; the gas stripping distillation unit comprises a first gas stripping module and a second gas stripping module which are connected with each other, a top liquid outlet of the first gas stripping module is connected with a feed port of the second gas stripping module, and primarily purified condensate discharged from the top of the first gas stripping module enters the second gas stripping module for secondary purification; the product collecting unit comprises a condensate storage tank, a deep condenser and a finished product storage tank which are sequentially connected in the material flow direction. According to the production system provided by the invention, the heat energy demand is remarkably reduced, the problems of huge equipment and high energy consumption are avoided, the production efficiency of deuterium water is improved, and environmental protection and economy are realized through resource recycling.

Description

Technical Field

[0001] This invention belongs to the field of low-deuterium water production technology, and relates to a low-deuterium water production system and method based on nitrogen stripping distillation. Background Technology

[0002] Low-deuterium water, generally referring to water with a deuterium content below 150 ppm, has attracted widespread attention due to its unique bioactivity in life sciences, disease prevention and treatment, and high-end health products. Currently, large-scale preparation methods for low-deuterium water mainly include distillation, electrolysis, and water / hydrogen dual-temperature exchange. Among these, distillation is the most widely used industrial method due to its relatively mature production process and the absence of catalysts or chemical reagents. Its basic principle is to utilize the small vapor pressure difference between deuterated water (HDO) and ordinary water (H2O) to achieve isotope separation through a distillation process. However, this method has an inherent drawback: the single-stage separation coefficient is extremely low, typically only between 1.03 and 1.06. To achieve effective deuterium removal, traditional processes must rely on multi-stage operations in a series of distillation columns tens of meters high, accompanied by repeated evaporation and condensation processes. This directly leads to problems such as large equipment structure, large footprint, high initial investment, and huge energy consumption. In addition, the high operating temperature of distillation columns (usually exceeding 100°C) places stringent requirements on system insulation and comprehensive utilization of thermal energy, further increasing operating costs.

[0003] While electrolysis can achieve high separation coefficients, its production process involves hydrogen generation and subsequent processing, posing significant safety hazards. It also places extremely high demands on storage equipment and safety protection systems, and overall energy consumption remains high. Although the water / hydrogen dual-temperature exchange method improves separation efficiency, its complex process, particularly its reliance on expensive platinum-based hydrophobic catalysts, results in high system construction costs. Furthermore, the difficulty in controlling parameters such as temperature and flow rate limits its widespread application. Existing multi-tower continuous distillation systems attempt to reduce tower height and utilize waste heat through structural optimization, but this increases system complexity and maintenance difficulty. Producing medical-grade low-deuterium water with a deuterium concentration below 50 ppm remains a challenge, and water resource utilization is low, with deuterium-rich water often discharged as wastewater, failing to achieve effective deuterium resource recovery.

[0004] In summary, current low-deuterium water production technologies generally face multiple contradictions between separation efficiency, energy consumption, safety, and cost. Developing a novel low-deuterium water preparation technology that can operate efficiently under mild conditions (such as lower temperatures), has controllable energy consumption, good safety, and enables the recycling of water and deuterium resources has become a key issue that urgently needs to be addressed in this field. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a distillation system and method for producing deuterium water based on nitrogen stripping.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a distillation-based low-deuterium water production system based on nitrogen stripping, the distillation-based low-deuterium water production system comprising a pretreatment unit, a stripping distillation unit and a product collection unit connected in sequence;

[0008] The pretreatment unit includes a raw water tank, a multi-stage filter, and an electro-deionization device connected sequentially along the material flow direction.

[0009] The stripping distillation unit includes a first stripping module and a second stripping module connected together. The condensate from the top of the first stripping module, which has undergone preliminary purification, enters the second stripping module for secondary purification.

[0010] The product collection unit includes a condensate storage tank, a deep condenser, and a finished product storage tank connected sequentially along the material flow direction.

[0011] The production system provided by this invention achieves efficient separation through raw material pretreatment, stepped gas stripping, and deep condensation. Compared with the high temperature and high pressure of traditional distillation methods, this system significantly reduces the heat energy requirement and avoids the problems of large equipment size and high energy consumption. At the same time, the use of nitrogen instead of hydrogen or chemical reagents eliminates safety hazards and simplifies the operation process. It not only improves the production efficiency of deuterium water, but also achieves environmental protection and economy through resource recycling, providing a feasible process route for the large-scale production of low-deuterium water.

[0012] In this invention, the pretreatment unit, through a raw water tank, multi-stage filters, and an electro-deionization device, ensures that suspended particles, organic matter, and ionic impurities are effectively removed from the raw water before it enters the stripping distillation unit, resulting in high-purity water with a resistivity ≥18 MΩ·cm. This high-purity raw water avoids interference from impurities in deuterium isotope separation, reduces mass transfer resistance, and thus improves separation efficiency. In traditional distillation methods, the presence of impurities often leads to scaling or decreased mass transfer efficiency. This invention solves this problem at its source by pretreating the raw water, enabling the stripping process to proceed under more stable conditions.

[0013] The stripping distillation unit employs a two-stage stripping module connected in series. The first stripping module performs preliminary purification of high-purity water, and the condensate discharged from its top enters the second stripping module for secondary purification. Under negative pressure and gentle heating conditions, isotope separation is achieved through countercurrent gas-liquid contact, utilizing the slight vapor pressure difference between deuterated water (HDO) and ordinary water (H2O). During the stripping process, nitrogen, as an inert gas, is introduced from the bottom of the stripping column and comes into countercurrent contact with the liquid sprayed from the top in the packing layer. Since the boiling point of HDO is slightly higher than that of H2O, under heating conditions, deuterium-deficient water vapor is more easily volatilized and forms a mixed gas with nitrogen, which is discharged from the top of the column, while deuterium-rich water accumulates at the bottom. The two-stage stripping design allows the separation process to be progressively deepened: the first stripping module performs coarse separation at lower pressure and lower temperature, removing most of the deuterium; the second stripping module performs fine separation at even lower pressure and lower temperature, further reducing the deuterium concentration. Two-stage stripping reduces the load on a single-stage stripping tower, avoiding the complexity and high energy consumption of traditional multi-tower series structures. Simultaneously, different types and densities of packing materials are used in the two-stage stripping towers, enhancing gas-liquid mass transfer efficiency and enabling the separation process to proceed efficiently within a relatively small tower height, overcoming the shortcomings of traditional distillation methods that rely on towers tens of meters high.

[0014] The product collection unit consists of a condensate storage tank, a deep condenser, and a finished product storage tank. The condensate discharged from the second stripping module undergoes secondary cooling in the deep condenser, further condensing residual water vapor and reducing the deuterium concentration of the low-deuterium water to below 50 ppm, meeting medical-grade standards. This step compensates for potential incomplete condensation issues during the stripping process, improving product yield.

[0015] As a preferred technical solution of the present invention, the first stripping module includes a first stripping tower, a first condenser and a first reboiler.

[0016] In some alternative instances, the top feed inlet of the first stripping column is connected to the outlet of the electro-deionization unit, the top gas outlet of the first stripping column is connected to the inlet of the first condenser, and the bottom liquid outlet of the first stripping column is connected to the inlet of the first reboiler.

[0017] In some optional instances, the second stripping module includes a second stripping tower, a second condenser, and a second reboiler. The top feed inlet of the second stripping tower is connected to the outlet of the first condenser, the top gas outlet of the second stripping tower is connected to the inlet of the second condenser, and the bottom liquid outlet of the second stripping tower is connected to the inlet of the second reboiler.

[0018] In some alternative examples, both the first and second stripping towers are filled with packing material, and the bottom of the first and second stripping towers is provided with nitrogen inlets. The top of the first and second stripping towers is provided with a first mist separator and a second mist separator, respectively.

[0019] In this invention, high-purity raw water enters from the top of the first stripping column. The gas outlet at the top is connected to the first condenser, and the liquid outlet at the bottom is connected to the first reboiler, forming a complete separation and reflux cycle. When the high-purity water is sprayed down from the top of the column and comes into countercurrent contact with the heated nitrogen gas introduced from the bottom, the mass transfer process takes place fully in the packed packing layer. The deuterium-poor water with a lower boiling point is more easily vaporized and discharged from the top of the column with the nitrogen gas, entering the first condenser. In the first condenser, most of the water vapor is condensed and recovered, and enters the second stripping module as the pre-purified liquid. The deuterium-rich water with a higher boiling point accumulates at the bottom of the column. Part of the deuterium-rich water at the bottom of the column is led to the first reboiler, heated to generate steam, and returned to the bottom of the column. This steam undergoes mass transfer exchange with the falling liquid again during its ascent, greatly enhancing the separation effect. The other part is discharged as deuterium-rich residue. By connecting the first reboiler to the bottom of the column, the energy waste and incomplete separation caused by the one-time evaporation in traditional distillation are avoided. The bottom product is continuously purified through internal reflux, thereby obtaining a higher purity deuterium-poor component at the top of the column.

[0020] The structure of the second stripping module is similar to that of the first stripping module. Its feed comes from the condensate of the first condenser, and the pre-purified condensate is further purified by the second stripping tower. Since the deuterium content of the condensate in the feed has been reduced, the second stripping tower can be operated at lower pressure and lower temperature, which is beneficial to further increase the relative volatility of HDO and H2O and achieve deep deuteration.

[0021] The packing material inside the two-stage stripping tower provides a huge mass transfer surface area for the gas and liquid phases, ensuring the high efficiency of countercurrent contact. The mist separator installed at the top of the tower can effectively capture the tiny liquid droplets entrained in the gas, preventing pure water products from being carried away by nitrogen. This reduces material loss and ensures the stable operation of the subsequent nitrogen circulation system, preventing liquid from entering the compressor and other equipment and causing damage.

[0022] As a preferred embodiment of the present invention, the distillation method for producing deuterium-rich water further includes a nitrogen circulation unit.

[0023] In some optional examples, the nitrogen circulation unit includes a nitrogen storage tank, a first gas heater, a second gas heater, and a circulation compressor, wherein the gas outlets of the first condenser and the second condenser are independently connected to the inlet of the circulation compressor, and the inlet of the circulation compressor is connected to the return port of the nitrogen storage tank.

[0024] In some optional examples, the outlet of the nitrogen storage tank is independently connected to the nitrogen inlet of the first stripping tower and the second stripping tower, respectively. A first gas heater is provided on the connecting pipeline between the nitrogen storage tank and the first stripping tower, and a second gas heater is provided on the connecting pipeline between the nitrogen storage tank and the second stripping tower.

[0025] This invention also incorporates a nitrogen circulation unit, enabling closed-loop nitrogen recovery and utilization. Uncondensed nitrogen discharged from the first and second condensers is collected and transported to a circulating compressor, pressurized, and returned to the nitrogen storage tank. This allows the nitrogen stripped in the two stripping towers to be recovered and reused, rather than being directly discharged. The closed-loop nitrogen circulation significantly reduces dependence on external nitrogen sources, saving on raw material costs while maintaining system stability. If nitrogen is continuously discharged and replenished, the newly injected nitrogen would cause fluctuations in pressure and temperature within the towers, disrupting the gas-liquid balance and mass transfer conditions. The closed-loop nitrogen circulation effectively isolates external interference, keeping the pressure, temperature, and gas composition within the towers stable.

[0026] Nitrogen, as an inert carrier gas, plays a crucial role in reducing the partial pressure of water vapor. Under a constant total system pressure, the presence of nitrogen dilutes the water vapor, allowing water molecules to gain sufficient kinetic energy and vaporize rapidly at temperatures far below their normal boiling points. This enables highly efficient water distillation separation within the column at a low temperature of 50-60°C. This low-temperature operation significantly reduces the heating energy consumption of the reboiler, avoiding the substantial energy losses and equipment insulation requirements associated with the high temperatures of traditional distillation methods. It also reduces the risk of equipment scaling and material corrosion, thus improving operational safety.

[0027] As a preferred technical solution of the present invention, the packing height of the packing in the first gas stripping tower is 8~12m, for example, it can be 8.0m, 8.5m, 9.0m, 9.5m, 10.0m, 10.5m, 11.0m, 11.5m or 12.0m, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] In some alternative examples, the packing bed in the first gas stripping tower is divided from top to bottom into a first demister section, a first mass transfer section, and a first gas distribution section.

[0029] In some optional instances, the packing height of the first demister section accounts for 10 to 20% of the total packing height, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0030] In some optional examples, the packing density of the first demister section is 100~150 kg / m³. 3 For example, it could be 100kg / m 3 105kg / m 3 110kg / m 3 115kg / m 3 120kg / m 3 125kg / m 3 130kg / m 3 135kg / m 3 140kg / m 3 145kg / m 3 Or 150kg / m 3 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0031] In some optional instances, the packing height of the first mass transfer section accounts for 60 to 80% of the total packing height, for example, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, or 80%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0032] In some optional examples, the packing density of the first mass transfer section is 150~200 kg / m³. 3 For example, it could be 150 kg / m 3 155kg / m 3 160kg / m 3 165kg / m 3 170kg / m 3 175kg / m 3 180kg / m 3 185kg / m 3 190kg / m 3 195kg / m 3 Or 200kg / m 3 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0033] In some optional instances, the packing height of the first gas distribution section accounts for 10 to 20% of the total packing height, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0034] In some optional examples, the packing density of the first gas distribution section is 200~250 kg / m³. 3 For example, it could be 200kg / m 3 205kg / m 3 210kg / m 3 215kg / m 3 220kg / m 3 225kg / m 3 230kg / m 3 235kg / m 3 240kg / m 3 245kg / m 3 Or 250kg / m 3 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0035] The total packing height of the first stripping tower is set at 8-12m to ensure sufficient contact path and time for the gas and liquid phases to achieve adequate mass transfer. The separation coefficient between deuterium water (HDO) and ordinary water (H2O) is extremely low, relying on numerous tiny evaporation-condensation equilibration processes on the packing surface for enrichment. When the tower height is below 8m, the number of theoretical plates is significantly reduced, resulting in insufficient gas-liquid contact time, poor separation efficiency, and the inability to reduce the deuterium concentration in the gas phase at the top of the tower to below the target value. While increasing the tower height can improve separation efficiency, it leads to higher equipment manufacturing costs, increased investment in plant height, and a higher overall system pressure drop. Excessive pressure drop requires the circulating compressor to provide greater power, causing a sharp increase in energy consumption and increasing the risk of flooding at the bottom of the packing layer.

[0036] This invention divides the packing bed of the first gas stripping tower into three sections, with the top demister section occupying 10-20% of the packing bed height and a packing density of 100-150 kg / m³. 3 The function of the demister section is to capture liquid droplets entrained in the gas. After the gas and liquid phases come into intense contact in the mass transfer section, the rising nitrogen gas flow carries a large number of micron-sized droplets. The demister section uses loose packing material with high porosity and large specific surface area, which is conducive to droplet collision, agglomeration, and gravity-induced fall. If the height of the demister section is too low or the packing density is too low, the capture efficiency will be insufficient, leading to product loss. More seriously, the droplets will enter the subsequent condenser and circulating compressor, causing equipment corrosion, reduced efficiency, or even mechanical failure. Conversely, if the height of the demister section is too high or the packing density is too high, the pressure drop in the demister section will increase significantly, and some vapor will be excessively condensed, forming unnecessary liquid reflux and disrupting the compositional balance at the top of the column.

[0037] The middle mass transfer section occupies 60% to 80% of the packing bed height, with a packing density of 150 to 200 kg / m³. 3The mass transfer section is mainly used for isotope separation. A high packing density provides a large specific surface area per unit volume, allowing the liquid to spread into a thin film and efficiently contact the rising nitrogen gas in a countercurrent flow. During this process, utilizing the small vapor pressure difference between HDO and H2O, under mild negative pressure and heating conditions, H2O more easily volatilizes into the gas phase, while HDO accumulates in the liquid phase at the bottom of the column. The height and packing density of the mass transfer section determine the degree of separation between HDO and H2O. If the height or packing density of the mass transfer section is too low, mass transfer is insufficient, and the purity of the gaseous product at the top of the column will not meet the standards. Conversely, if the height or packing density of the mass transfer section is too high, although theoretically the separation effect is better, it will lead to a sharp increase in pressure drop within the column, a significant increase in energy consumption, and a high risk of flooding in the lower part of the column, disrupting normal operation.

[0038] The gas distribution section at the bottom occupies 10% to 20% of the packing bed height, with a packing density of 200 to 250 kg / m³. 3 The function of the gas distribution section is to rectify and initially distribute the nitrogen gas entering the tower. The nitrogen gas entering from the bottom inlet is turbulent and unevenly distributed. By filling the bottom with high-density, small-sized packing material to create a uniform resistance layer, the large gas flow is effectively broken into numerous smaller flow streams, forcing them to distribute evenly across the entire tower cross-section before smoothly entering the mass transfer section above. If the height of the gas distribution section is too low or the packing density is too low, the uneven distribution of nitrogen gas will lead to channeling and dead zones in the mass transfer section. Gas will concentrate in some channels while remaining inaccessible in others, significantly reducing the effective mass transfer area and resulting in a marked decrease in separation efficiency. Conversely, if the height of the gas distribution section is too high or the packing density is too high, although the nitrogen gas flow distribution is better, it will cause unnecessary inlet pressure loss, increase compressor energy consumption, and hinder the smooth descent of liquid within the tower.

[0039] As a preferred technical solution of the present invention, the packing height of the packing in the second gas stripping tower is 15~20m, for example, it can be 15m, 15.5m, 16m, 16.5m, 17m, 17.5m, 18m, 18.5m, 19m, 19.5m or 20m, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] In some alternative examples, the packing bed in the second stripping tower is divided from top to bottom into a second demister section, a second mass transfer section, and a second gas distribution section.

[0041] In some optional instances, the packing height of the second demister section accounts for 10 to 20% of the total packing height, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0042] In some optional examples, the packing density of the second demister section is 100~150 kg / m³. 3 For example, it could be 100kg / m 3 105kg / m 3 110kg / m 3 115kg / m 3 120kg / m 3 125kg / m 3 130kg / m 3 135kg / m 3 140kg / m 3 145kg / m 3 Or 150kg / m 3 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0043] In some optional instances, the packing height of the second mass transfer section accounts for 60 to 80% of the total packing height, for example, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, or 80%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0044] In some optional examples, the packing density of the second mass transfer section is 150~200 kg / m³. 3 For example, it could be 150 kg / m 3 155kg / m 3 160kg / m 3 165kg / m 3 170kg / m 3 175kg / m 3 180kg / m 3 185kg / m 3 190kg / m 3 195kg / m 3 Or 200kg / m 3 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0045] In some optional instances, the packing height of the second gas distribution section accounts for 10 to 20% of the total packing height, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0046] In some optional examples, the packing density of the second gas distribution section is 200~250 kg / m³. 3 For example, it could be 200kg / m 3 205kg / m 3 210kg / m 3 215kg / m 3 220kg / m 3 225kg / m 3 230kg / m 3 235kg / m 3 240kg / m 3 245kg / m 3 Or 250kg / m 3 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0047] The main function of the second stripping tower is to further purify the preliminary purified solution from the first stripping tower to a deuterium concentration of ≤50ppm. Because the separation coefficient is small at low concentrations, increasing the difficulty of separation, the total packing height of its packing material is set at 15-20m, significantly higher than that of the first stripping tower. This height range ensures that the gas and liquid phases have a sufficiently long contact path and contact time to complete numerous fine equilibrium separations under extremely low operating pressures. If the packing height is too low, the separation will be incomplete, and the product purity will not meet the standards; if the packing height is too high, although it can slightly improve the purity, the equipment cost and fluid pressure drop will increase significantly, resulting in excessive energy consumption and a high risk of flooding.

[0048] As a preferred embodiment of the present invention, the packing material filled in the first and second demisting sections is 350Y type structured packing.

[0049] In some optional instances, the packing material in the first and second mass transfer sections is 250Y structured packing.

[0050] In some optional instances, the packing material in the first gas distribution section and the second gas distribution section is 125Y type structured packing.

[0051] In some optional instances, a first liquid redistributor is provided between the first demister section and the first mass transfer section, and between the first mass transfer section and the first gas distribution section.

[0052] In some optional instances, a second liquid redistributor is provided between the second demister section and the second mass transfer section, and between the second mass transfer section and the second gas distribution section.

[0053] This invention fills the packing sections of the gas stripping tower with specific types of structured packing and adds a liquid redistributor, which significantly improves separation efficiency and operational stability.

[0054] 350Y structured packing is selected for the demisting section. This type of packing has a large specific surface area and porosity. Its blades have a large inclination angle and wide channels, providing ample space for the collision and aggregation of fine droplets when airflow carrying them passes through, allowing them to effectively separate and fall back under gravity. This highly efficient demisting capability protects the downstream condenser and circulating compressor, ensuring the long-term stable operation of the nitrogen circulation system while reducing the loss of high-value products.

[0055] The mass transfer section is the core of the separation process. In this invention, the mass transfer section is filled with 250Y structured packing. Compared with the 350Y structured packing in the demisting section, the 250Y structured packing has a larger specific surface area, providing a sufficient contact interface for the gas and liquid phases, which is beneficial to the mass transfer and separation of H2O and HDO.

[0056] The gas distribution section uses 125Y structured packing, which is characterized by smaller size and higher density. The bed resistance formed by this packing is uniform and large, which can effectively disperse the unevenly distributed nitrogen gas flow entering from the bottom of the tower and force it to be evenly distributed across the entire cross-section of the tower.

[0057] Secondly, the present invention provides a production method using the distillation method for producing low-deuterium water as described in the first aspect, the production method comprising:

[0058] The raw water is passed through the multi-stage filter to remove suspended particles and organic matter, and then enters the electro-deionization water device for deep deionization to obtain high-purity water.

[0059] High-purity water and nitrogen are introduced into the first gas stripping module. After nitrogen stripping, the pre-purified condensate is discharged from the first gas stripping module. The condensate enters the second gas stripping module, and after nitrogen stripping, it is discharged from the second gas stripping module into the condensate storage tank. After secondary condensation in the deep condenser, low-deuterium water is obtained.

[0060] As a preferred technical solution of the present invention, the production method specifically includes the following steps:

[0061] The raw water is passed through the multi-stage filter to remove suspended particles and organic matter, and then enters the electro-deionization water device for deep deionization to obtain high-purity water.

[0062] The high-purity water is sprayed into the first stripping tower from the top. At the same time, the nitrogen stored in the nitrogen storage tank is heated by the first gas heater and then introduced into the first stripping tower from the bottom. Under negative pressure and heating environment, the high-purity water and nitrogen come into countercurrent contact in the packing layer of the first stripping tower. The deuterium-rich water, due to its higher boiling point, accumulates at the bottom of the tower. The mixture of deuterium-poor water vapor and nitrogen is discharged from the top of the first stripping tower and enters the first condenser. Part of the deuterium-rich water collected at the bottom of the first stripping tower is returned to the first reboiler for recycling, and part is discharged from the first stripping tower.

[0063] Uncondensed nitrogen in the first condenser is discharged into the circulating compressor. After being pressurized by the circulating compressor, it returns to the nitrogen storage tank for recycling. The condensate obtained after condensation in the first condenser is preheated and sprayed into the second stripping tower from the top. At the same time, the nitrogen stored in the nitrogen storage tank is heated by the second gas heater and then introduced into the second stripping tower from the bottom. Under negative pressure and heating environment, the condensate and nitrogen come into countercurrent contact in the packing layer in the second stripping tower. Deuterium-rich water, due to its higher boiling point, accumulates at the bottom of the tower. The mixture of deuterium-poor water vapor and nitrogen is discharged from the top of the second stripping tower and enters the second condenser. Part of the deuterium-rich water collected at the bottom of the second stripping tower is returned to the second reboiler for recycling, and part is discharged from the second stripping tower.

[0064] Uncondensed nitrogen in the second condenser is discharged into the circulating compressor. After being pressurized by the circulating compressor, it returns to the nitrogen storage tank for recycling. The condensate obtained after condensation in the second condenser enters the condensate storage tank and is then condensed again by the deep condenser to obtain low-deuterium water, which is stored in the finished product storage tank.

[0065] This invention deeply purifies raw water using multi-stage filters and an electro-deionization water device to obtain high-purity water, effectively preventing impurities from interfering with the mass transfer process or causing scale buildup in the equipment. Subsequently, the high-purity water is sprayed down from the top of the first stripping tower and comes into countercurrent contact with heated nitrogen gas entering from the bottom of the tower in the packing layer. Under negative pressure and gentle heating conditions, utilizing the vapor pressure difference between HDO and H2O, H2O, with its slightly lower boiling point, more easily volatilizes into the gas phase, while HDO tends to accumulate in the liquid phase. Some of the deuterium-rich water at the bottom of the tower is heated and vaporized by the first reboiler and returned to the tower. This rising vapor and descending liquid undergo mass transfer again, greatly enhancing the separation effect. By controlling the reflux ratio, the purity of the product at the top of the tower can be precisely controlled. The preliminarily purified vapor-nitrogen mixture is condensed by the first condenser, achieving preliminary gas-liquid separation.

[0066] The deuterium content in the condensate obtained after condensation in the first condenser has been significantly reduced. It is then sent to the second stripping tower for further purification. The second stripping tower operates at lower pressures and temperatures, further increasing the relative volatility of H₂O to HDO, enabling ultimate deuterium removal from the already purified material. This results in a low-deuterium water product with a deuterium concentration ≤50 ppm. Simultaneously, the uncondensed nitrogen discharged from both condensers is collected and pressurized by a circulating compressor and returned to the stripping tower for reuse. This not only significantly reduces nitrogen consumption but also maintains stable operating conditions within the tower, avoiding fluctuations caused by continuous replenishment of new nitrogen.

[0067] The condensate obtained from the second condenser is further cooled by the deep condenser, which maximizes the condensation of residual water vapor and improves the product yield. At the same time, the low temperature also promotes the escape of trace gases dissolved in the water, ensuring that the final product has extremely low deuterium purity.

[0068] As a preferred embodiment of the present invention, the resistivity of the high-purity water is ≥18 MΩ·cm, for example, it can be 8 MΩ·cm, 9 MΩ·cm, 10 MΩ·cm, 11 MΩ·cm, 12 MΩ·cm, 13 MΩ·cm, 14 MΩ·cm, 15 MΩ·cm, 16 MΩ·cm, 17 MΩ·cm or 18 MΩ·cm, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0069] In some optional instances, the nitrogen gas is preheated to 55-65°C by the first gas heater before being introduced into the first gas stripping tower. For example, the temperature may be 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, or 65°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0070] In some optional examples, the spray rate of the high-purity water in the first stripping tower is 3~6m³.3 / h, for example, could be 3.0m 3 / h, 3.5m 3 / h, 4.0m 3 / h, 4.5m 3 / h, 5.0m 3 / h, 5.5m 3 / h or 6.0m 3 / h, but not limited to the listed values; other unlisted values ​​within this range also apply.

[0071] This invention specifically limits the spray volume of high-purity water in the first stripping tower to 3~6m³. 3 / h, if the spray volume of high-purity water is less than 3m 3 If the liquid flow rate per unit time is insufficient, the packing material cannot be fully wetted, the effective mass transfer area is significantly reduced, and the liquid cannot flow along the packing surface in an ideal thin film, even resulting in dry zones. This leads to insufficient gas-liquid phase contact and a significant decrease in isotope separation efficiency. Conversely, if the high-purity water spray rate exceeds 6 m³ / h, the liquid flow rate per unit time is insufficient. 3 At a rate of / h, the liquid holdup in the tower will increase dramatically. The liquid in the packing layer occupies too much space, blocking the gas passage and increasing the resistance of the gas through the packing layer. This not only significantly increases the energy consumption of the circulating compressor but also leads to flooding, where liquid accumulates in the tower, completely disrupting the normal gas-liquid countercurrent operation.

[0072] In some optional instances, the flow rate of nitrogen in the first stripping tower is 60-90 m³ / h. 3 / h, for example, could be 60m 3 / h、65m 3 / h, 70m 3 / h、75m 3 / h、80m 3 / h、85m 3 / h or 90m 3 / h, but not limited to the listed values; other unlisted values ​​within this range also apply.

[0073] This invention specifically limits the flow rate of nitrogen in the first stripping tower to 60-90 m³ / h. 3 / h, if the nitrogen flow rate is less than 60m 3 If the nitrogen flow rate is too low (e.g., 90 m³ / h), its effect on reducing the partial pressure of water vapor will be weakened, which is not conducive to the full vaporization of water at low temperatures and weakens the driving force for gas stripping separation. Furthermore, excessively low gas velocities cannot effectively shear and turbulently move the descending liquid, resulting in slow gas-liquid interface renewal and reduced mass transfer efficiency. Conversely, if the nitrogen flow rate exceeds 90 m³ / h... 3At a gas velocity of / h, a large number of fine droplets will be entrained. Even if there is a demister at the top of the column, excessive droplet entrainment will increase its burden, leading to product loss and damage to downstream equipment.

[0074] In some optional instances, the operating pressure of the first stripping tower is 5 to 10 kPa, for example, it can be 5.0 kPa, 5.5 kPa, 6.0 kPa, 6.5 kPa, 7.0 kPa, 7.5 kPa, 8.0 kPa, 8.5 kPa, 9.0 kPa, 9.5 kPa or 10.0 kPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0075] This invention sets the operating pressure of the first stripping tower to 5-10 kPa, which significantly lowers the boiling point of water. Under this pressure, the temperature at which water undergoes vigorous vaporization can be reduced to 50-60°C, far below 100°C at atmospheric pressure. This low-temperature operation drastically reduces the heat energy demand of the reboiler, achieving low-energy operation. Furthermore, low-temperature operation also reduces the requirements for the high-temperature resistance of equipment materials, reducing equipment investment costs, greatly alleviating scaling and corrosion problems that may occur at high temperatures, and improving the long-term operational stability of the system.

[0076] However, lower operating pressure is not always better. If the operating pressure is below 5 kPa, although the boiling point will decrease further, it places higher demands on the capability and reliability of the vacuum system. Creating and maintaining such a high vacuum requires more powerful and expensive vacuum equipment, which will drastically increase energy consumption and maintenance costs. In addition, at extremely low operating pressures, the gas volume will expand abnormally, resulting in excessively high gas velocity inside the column, which can easily cause flooding and disrupt normal operation.

[0077] In some optional instances, the temperature inside the first stripping tower is 50~60°C, for example, it can be 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0078] In some alternative instances, the reflux ratio of the first stripping tower is 5 to 8, for example, it can be 5.0, 5.5, 6.0, 6.5, 7.0, 7.5 or 8.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0079] This invention specifically limits the reflux ratio of the first stripping tower to 5-8. If the reflux ratio is less than 5, the amount of reflux liquid in the tower is insufficient, the mass transfer driving force on the packing surface is weakened, and the gas and liquid phases cannot carry out sufficient mass exchange, which ultimately leads to a poor separation effect. The vapor rising from the top of the tower will contain more deuterium water molecules (HDO) that should remain at the bottom of the tower, resulting in low purity of the initially purified condensate. This will bring an excessive separation load to the subsequent second stripping tower, resulting in the final product not meeting the purity standard.

[0080] While a reflux ratio exceeding 8 theoretically enhances separation and increases the purity of the top product, it also leads to a sharp increase in energy consumption. Firstly, a high reflux ratio means a larger amount of vapor needs to be condensed at the top of the column and returned, significantly increasing the cooling load on the condenser. Secondly, to generate a large amount of reflux liquid, the reboiler at the bottom of the column must provide substantial heat for vaporization, resulting in a significant increase in thermal energy consumption.

[0081] In some alternative instances, the cooling temperature of the mixed gas in the first condenser is 5 to 10°C, for example, 5.0°C, 5.5°C, 6.0°C, 6.5°C, 7.0°C, 7.5°C, 8.0°C, 8.5°C, 9.0°C, 9.5°C, or 10.0°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0082] As a preferred technical solution of the present invention, the condensate obtained after condensation in the first condenser is preheated to 30~40°C and then sprayed into the second gas stripping tower from the top of the tower. For example, it can be 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C or 40°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0083] In some optional instances, the nitrogen gas is preheated to 35-45°C by the second gas heater before being introduced into the second gas stripping tower. For example, the temperature may be 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, or 45°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0084] In some optional examples, the spray rate of the condensate in the second stripping tower is 1~3m³. 3 / h, for example, could be 1.0m 3 / h, 1.2m 3 / h, 1.4m 3 / h, 1.6m 3 / h, 1.8m 3 / h, 2.0m 3 / h, 2.2m3 / h, 2.4m 3 / h, 2.6m 3 / h, 2.8m 3 / h or 3.0m 3 / h, but not limited to the listed values; other unlisted values ​​within this range also apply.

[0085] The feed to the second gas column is the pre-purified condensate discharged from the first condenser, whose deuterium content has been significantly reduced, making further purification to ≤50ppm correspondingly more difficult. (The last part, "1~3m," appears to be an unrelated fragment and is omitted from the translation.) 3 At lower spray rates ( / h), less condensate needs to be treated, but a higher degree of separation is required. If the spray rate is less than 1m³ / h... 3 A spray rate of 3 m³ / h leads to insufficient wetting of the packing surface, reducing the effective mass transfer area. Maintaining a stable liquid distribution becomes more difficult under such low liquid loads, and wall flow easily occurs, preventing the packing in the central region from participating in mass transfer and severely reducing separation efficiency. Conversely, if the spray rate exceeds 3 m³ / h... 3 At the extremely low operating pressure of the second stripping tower, the increase in liquid holdup in the tower will lead to a significant increase in fluid resistance and a rapid rise in pressure drop in the tower. This will not only greatly increase the energy consumption of the compressor, but also cause flooding and disrupt the stable gas-liquid countercurrent operation in the tower.

[0086] In some optional examples, the flow rate of nitrogen in the second stripping tower is 30-50 m³ / h. 3 / h, for example, could be 30m 3 / h、32m 3 / h、34m 3 / h、36m 3 / h, 38m 3 / h, 40m 3 / h、42m 3 / h、44m 3 / h、46m 3 / h、48m 3 / h or 50m 3 / h, but not limited to the listed values; other unlisted values ​​within this range also apply.

[0087] The main function of nitrogen is to lower the partial pressure of water vapor and promote the low-temperature vaporization of water. If the nitrogen flow rate is below 30 m³ / h... 3 At low total pressures, nitrogen flow rate ( / h) is insufficient as a carrier gas for dilution, making it difficult to provide enough lift force to drive the mass transfer process required for limiting distillation. Simultaneously, excessively low gas velocities fail to effectively disturb the descending liquid, resulting in slow gas-liquid interface renewal and reduced mass transfer efficiency. Conversely, if the nitrogen flow rate exceeds 50 m³ / h... 3At extremely low operating pressures, the air velocity in the empty tower becomes too high, resulting in a huge airflow shear force that exacerbates mist entrainment. Even with a high-efficiency demisting section, trace amounts of high-deuterium droplets can still contaminate the pure product at the top of the tower.

[0088] In some alternative instances, the operating pressure of the second stripping tower is 2 to 5 kPa, for example, 2.0 kPa, 2.2 kPa, 2.4 kPa, 2.6 kPa, 2.8 kPa, 3.0 kPa, 3.2 kPa, 3.4 kPa, 3.6 kPa, 3.8 kPa, 4.0 kPa, 4.2 kPa, 4.4 kPa, 4.6 kPa, 4.8 kPa or 5.0 kPa, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0089] This invention further reduces the operating pressure of the second stripping tower to 2-5 kPa, maximizing the relative volatility between ordinary water (H2O) and deuterated water (HDO). At extremely high purity, the slight difference in their boiling points is the sole driving force for separation. According to the principle of vapor-liquid balance, reducing the total system pressure can effectively increase the relative volatility, thereby significantly enhancing the driving force for separation. This allows the residual trace amounts of HDO to be separated from the bulk H2O in the low-pressure environment of the second stripping tower.

[0090] In some optional instances, the temperature inside the second stripping tower is 35~45°C, for example, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C or 45°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0091] In some alternative instances, the reflux ratio of the second stripping tower is 10 to 12, for example, it can be 10, 10.2, 10.4, 10.6, 10.8, 11, 11.2, 11.4, 11.6, 11.8 or 12, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0092] The second stripping column employs a high reflux ratio of 10-12. The feed to the second stripping column is the pre-purified condensate, and further removal of the remaining trace amounts of deuterium water presents a significant separation challenge. A high reflux ratio means that a large amount of condensed, highly pure liquid returns to the top of the column, engaging in countercurrent contact with the rising vapor. This provides a powerful driving force for gas-liquid mass transfer under high-purity conditions, essentially washing the rising vapor repeatedly with a large amount of pure liquid, ensuring that the vapor discharged from the top of the column meets the ultra-low deuterium content requirement. If the reflux ratio is below 10, the reflux flow rate within the column is insufficient, the mass transfer driving force is reduced, making further purification of the condensate difficult, and the product purity cannot meet the requirement of ≤50ppm.

[0093] However, a high reflux ratio also means high energy consumption. The reflux liquid is condensed from the steam at the top of the column. A high reflux ratio requires the reboiler to provide a large amount of heat to generate a corresponding amount of steam, and a condenser is needed to remove this heat. If the reflux ratio exceeds 12, although the purity may be slightly improved, the heat energy consumption and cooling water consumption will increase sharply, the equipment load will increase, and the economic efficiency will be significantly reduced.

[0094] In some alternative instances, the cooling temperature of the mixed gas in the second condenser is 5 to 10°C, for example, 5.0°C, 5.5°C, 6.0°C, 6.5°C, 7.0°C, 7.5°C, 8.0°C, 8.5°C, 9.0°C, 9.5°C, or 10.0°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0095] The second condenser cools the mixed gas to 5-10°C. Its function is to efficiently separate nitrogen and deuterium-rich water products. This temperature range ensures that most of the water vapor can be condensed and recovered, thus guaranteeing product yield. If the cooling temperature exceeds 10°C, a large amount of water vapor will not be able to condense and will enter the circulating compressor with the nitrogen, causing not only product loss but also damage to the circulating compressor from water vapor droplets. If the cooling temperature is below 5°C, although condensation can be more thorough, energy consumption will increase dramatically.

[0096] In some alternative instances, the cooling temperature of the condensate within the deep condenser is 0 to 5°C, for example, 0°C, 0.5°C, 1°C, 1.5°C, 2°C, 2.5°C, 3°C, 3.5°C, 4°C, 4.5°C, or 5°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0097] The deep condenser further cools the condensate to 0-5°C, which improves product purity and stability. Trace amounts of gas remain dissolved in the liquid after the second condenser. According to Henry's Law, the lower the temperature, the lower the solubility of a gas. This low-temperature condition maximizes the escape of dissolved gases, preventing them from contaminating the final product and affecting its purity.

[0098] In some alternative instances, the deuterium concentration of the low-deuterium water is ≤50ppm, for example, it may be 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, 45ppm or 50ppm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0099] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0100] The production system provided by this invention achieves efficient separation through raw material pretreatment, stepped gas stripping, and deep collection. Compared with the high temperature and high pressure of traditional distillation methods, this system significantly reduces the heat energy requirement and avoids the problems of large equipment size and high energy consumption. At the same time, the use of nitrogen instead of hydrogen or chemical reagents eliminates safety hazards and simplifies the operation process. It not only improves the production efficiency of deuterium water, but also achieves environmental protection and economy through resource recycling, providing a feasible process route for the large-scale production of low-deuterium water. Attached Figure Description

[0101] Figure 1 This is a schematic diagram of the distillation method for producing deuterium-rich water provided in Embodiments 1-5 of the present invention.

[0102] The components are as follows: 1-raw water tank; 2-multi-stage filter; 3-electrodeionization device; 4-first gas stripping tower; 5-first demister section; 6-first mass transfer section; 7-first gas distribution section; 8-first liquid redistributor; 9-first mist separator; 10-first reboiler; 11-first condenser; 12-second gas stripping tower; 13-second demister section; 14-second mass transfer section; 15-second gas distribution section; 16-second liquid redistributor; 17-second mist separator; 18-second reboiler; 19-second condenser; 20-condensate storage tank; 21-deep condenser; 22-finished product storage tank; 23-circulating compressor; 24-nitrogen storage tank; 25-first gas heater; 26-second gas heater. Detailed Implementation

[0103] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0104] Example 1

[0105] exist Figure 1 In the embodiment shown, this embodiment provides a nitrogen stripping distillation method for producing low-deuterium water. The distillation method for producing low-deuterium water includes a pretreatment unit, a stripping distillation unit, and a product collection unit connected in sequence.

[0106] The pretreatment unit includes a raw water tank 1, a multi-stage filter 2, and an electro-deionization device 3, which are connected sequentially along the material flow direction.

[0107] The stripping distillation unit includes a first stripping module and a second stripping module connected together. The condensate from the top of the first stripping module, which has undergone preliminary purification, enters the second stripping module for secondary purification.

[0108] The product collection unit includes a condensate storage tank 20, a deep condenser 21, and a finished product storage tank 22, which are connected sequentially along the material flow direction.

[0109] The first stripping module includes a first stripping tower 4, a first condenser 11, and a first reboiler 10. The top feed inlet of the first stripping tower 4 is connected to the outlet of the electro-deionization device 3, the top gas outlet of the first stripping tower 4 is connected to the inlet of the first condenser 11, and the bottom liquid outlet of the first stripping tower 4 is connected to the inlet of the first reboiler 10.

[0110] The second stripping module includes a second stripping tower 12, a second condenser 19, and a second reboiler 18. The top feed inlet of the second stripping tower 12 is connected to the outlet of the first condenser 11, the top gas outlet of the second stripping tower 12 is connected to the inlet of the second condenser 19, and the bottom liquid outlet of the second stripping tower 12 is connected to the inlet of the second reboiler 18.

[0111] The interior of the first stripping tower 4 and the second stripping tower 12 are both filled with packing material. Nitrogen inlets are provided at the bottom of the first stripping tower 4 and the second stripping tower 12. A first mist separator 9 and a second mist separator 17 are respectively provided at the top of the first stripping tower 4 and the second stripping tower 12.

[0112] The total packing height of the packing in the first gas stripping tower 4 is 8m. The packing bed in the first gas stripping tower 4 is divided into a first demister section 5, a first mass transfer section 6, and a first gas distribution section 7 from top to bottom. Among them, the packing in the first demister section 5 is 350Y type structured packing, and its packing height accounts for 10% of the total packing height, with a packing density of 150kg / m³. 3 The first mass transfer section 6 is filled with 250Y type structured packing, with a filling height accounting for 80% of the total packing height and a filling density of 200 kg / m³. 3 The first gas distribution section 7 is filled with 125Y type structured packing, with a filling height accounting for 10% of the total packing height and a filling density of 250 kg / m³. 3 .

[0113] The packing height of the packing in the second stripping tower 12 is 15m; the packing bed in the second stripping tower 12 is divided into a second demister section 13, a second mass transfer section 14, and a second gas distribution section 15 from top to bottom; the packing in the second demister section 13 is 350Y type structured packing, its packing height accounts for 10% of the total packing height, and its packing density is 150kg / m³. 3The second mass transfer section 14 is filled with 250Y type structured packing, with a filling height accounting for 80% of the total packing height and a filling density of 200 kg / m³. 3 The second gas distribution section 15 is filled with 125Y type structured packing, with a filling height accounting for 10% of the total packing height and a filling density of 250 kg / m³. 3 .

[0114] A first liquid redistributor 8 is provided between the first demisting section 5 and the first mass transfer section 6, and between the first mass transfer section 6 and the first gas distribution section 7; a second liquid redistributor 16 is provided between the second demisting section 13 and the second mass transfer section 14, and between the second mass transfer section 14 and the second gas distribution section 15.

[0115] exist Figure 1 In the illustrated embodiment, the distillation method for producing deuterium-rich water further includes a nitrogen circulation unit, which includes a nitrogen storage tank 24, a first gas heater 25, a second gas heater 26, and a circulation compressor 23. The gas outlets of the first condenser 11 and the second condenser 19 are independently connected to the inlet of the circulation compressor 23, and the inlet of the circulation compressor 23 is connected to the return port of the nitrogen storage tank 24.

[0116] The outlet of the nitrogen storage tank 24 is independently connected to the nitrogen inlet of the first gas stripping tower 4 and the second gas stripping tower 12. A first gas heater 25 is installed on the connecting pipeline between the nitrogen storage tank 24 and the first gas stripping tower 4, and a second gas heater 26 is installed on the connecting pipeline between the nitrogen storage tank 24 and the second gas stripping tower 12.

[0117] This embodiment also provides a production method for preparing deuterium-free water using the above-described production system, specifically including the following steps:

[0118] The raw water is passed through a multi-stage filter 2 to remove suspended particles and organic matter, and then enters an electro-deionization water device to further remove ions, resulting in high-purity water with a resistivity of 15 MΩ·cm.

[0119] High-purity water at 3m 3 A flow rate of / h is sprayed into the first stripping tower 4 from the top of the tower. At the same time, nitrogen stored in nitrogen storage tank 24 is heated to 55°C by the first gas heater 25 and then sprayed out at a flow rate of 60m³ / h. 3A flow rate of / h is introduced into the first stripping tower 4 from the bottom of the tower. Under an operating pressure of 5kPa and a tower temperature of 50℃, high-purity water and nitrogen gas are in countercurrent contact in the packing layer of the first stripping tower 4. The reflux ratio of the first stripping tower 4 is 8. Due to its higher boiling point, the deuterium-rich water is enriched at the bottom of the tower. The mixture of deuterium-poor water vapor and nitrogen gas is discharged from the top of the first stripping tower 4 and enters the first condenser 11. It is condensed at 5℃ to obtain condensate. Part of the deuterium-rich water collected at the bottom of the first stripping tower 4 is returned to the first reboiler 10 for recycling, and part is discharged from the first stripping tower 4.

[0120] Uncondensed nitrogen in the first condenser 11 is discharged into the circulating compressor 23. After being pressurized by the circulating compressor 23, it returns to the nitrogen storage tank 24 for reuse. The condensate obtained after condensation in the first condenser 11 is preheated to 30°C and then discharged at 1m³. 3 A flow rate of / h is sprayed into the second stripping tower 12 from the top. Simultaneously, nitrogen stored in nitrogen storage tank 24 is heated to 35°C by the second gas heater 26 and then discharged at a rate of 30m³ / h. 3 A flow rate of / h is introduced into the second stripping tower 12 from the bottom of the tower. Under an operating pressure of 2kPa and a tower temperature of 35℃, the condensate and nitrogen gas are in countercurrent contact in the packing layer of the second stripping tower 12. The reflux ratio of the second stripping tower 12 is 12. The deuterium-rich water is enriched at the bottom of the tower due to its higher boiling point. The mixture of deuterium-deficient water vapor and nitrogen gas is discharged from the top of the second stripping tower 12 and enters the second condenser 19. It is condensed at 5℃ to obtain condensate. Part of the deuterium-rich water collected at the bottom of the second stripping tower 12 is returned to the second reboiler 18 for recycling, and part is discharged from the second stripping tower 12.

[0121] Uncondensed nitrogen in the second condenser 19 is discharged from the second condenser 19 and enters the circulating compressor 23. After being pressurized by the circulating compressor 23, it returns to the nitrogen storage tank 24 for recycling. The condensate obtained after condensation in the second condenser 19 enters the condensate storage tank 20, and then undergoes secondary condensation at 0°C by the deep condenser 21 to obtain low deuterium water with a concentration of 48.5 ppm, which is stored in the finished product storage tank 22.

[0122] Example 2

[0123] exist Figure 1 In the illustrated embodiment, this embodiment provides a nitrogen stripping-based distillation system for producing low-deuterium water. The difference from Embodiment 1 is that the total packing height of the packing material in the first stripping tower 4 is 9m; the packing material in the first demister section 5 is 350Y type structured packing material, with a packing height accounting for 12% of the total packing height and a packing density of 130kg / m³. 3 The first mass transfer section 6 is filled with 250Y type structured packing, which accounts for 76% of the total packing height, and has a packing density of 180 kg / m³. 3The first gas distribution section 7 is filled with 125Y type structured packing, which accounts for 12% of the total packing height, and has a packing density of 230 kg / m³. 3 .

[0124] The packing height in the second stripping tower 12 is 16m; the packing in the second demister section 13 is 350Y type structured packing, with a packing height accounting for 12% of the total packing height and a packing density of 130kg / m³. 3 The second mass transfer section 14 is filled with 250Y type structured packing, which accounts for 76% of the total packing height, and has a packing density of 180 kg / m³. 3 The second gas distribution section 15 is filled with 125Y type structured packing, which accounts for 12% of the total packing height, and has a packing density of 230 kg / m³. 3 .

[0125] The other structures are exactly the same as in Example 1.

[0126] This embodiment also provides a production method for preparing deuterium-free water using the above-described production system, specifically including the following steps:

[0127] The raw water is passed through a multi-stage filter 2 to remove suspended particles and organic matter, and then enters an electro-deionization water device to further remove ions, resulting in high-purity water with a resistivity of 16 MΩ·cm.

[0128] High-purity water at 4m 3 A flow rate of / h is sprayed into the first stripping tower 4 from the top of the tower. At the same time, nitrogen stored in nitrogen storage tank 24 is heated to 58°C by the first gas heater 25 and then sprayed at 70m³ / h. 3 A flow rate of / h is introduced into the first stripping tower 4 from the bottom of the tower. Under an operating pressure of 6kPa and an internal temperature of 52℃, high-purity water and nitrogen gas are in countercurrent contact in the packing layer of the first stripping tower 4. The reflux ratio of the first stripping tower 4 is 7. Due to its higher boiling point, the deuterium-rich water is enriched at the bottom of the tower. The mixture of deuterium-poor water vapor and nitrogen gas is discharged from the top of the first stripping tower 4 and enters the first condenser 11. It is condensed at 6℃ to obtain condensate. Part of the deuterium-rich water collected at the bottom of the first stripping tower 4 is returned to the first reboiler 10 for recycling, and part is discharged from the first stripping tower 4.

[0129] Uncondensed nitrogen in the first condenser 11 is discharged into the circulating compressor 23. After being pressurized by the circulating compressor 23, it returns to the nitrogen storage tank 24 for reuse. The condensate obtained after condensation in the first condenser 11 is preheated to 32°C and then discharged at a rate of 1.5m³. 3A flow rate of / h is sprayed into the second stripping tower 12 from the top. Simultaneously, nitrogen stored in nitrogen storage tank 24 is heated to 38°C by the second gas heater 26 and then discharged at a rate of 35m³ / h. 3 A flow rate of / h is introduced into the second stripping tower 12 from the bottom of the tower. Under an operating pressure of 3kPa and a tower temperature of 38℃, the condensate and nitrogen gas are in countercurrent contact in the packing layer of the second stripping tower 12. The reflux ratio of the second stripping tower 12 is 11. The deuterium-rich water is enriched at the bottom of the tower due to its higher boiling point. The mixture of deuterium-poor water vapor and nitrogen gas is discharged from the top of the second stripping tower 12 and enters the second condenser 19. It is condensed at 6℃ to obtain condensate. Part of the deuterium-rich water collected at the bottom of the second stripping tower 12 is returned to the second reboiler 18 for recycling, and part is discharged from the second stripping tower 12.

[0130] Uncondensed nitrogen in the second condenser 19 is discharged from the second condenser 19 and enters the circulating compressor 23. After being pressurized by the circulating compressor 23, it returns to the nitrogen storage tank 24 for recycling. The condensate obtained after condensation in the second condenser 19 enters the condensate storage tank 20, and then undergoes secondary condensation at 1°C by the deep condenser 21 to obtain low deuterium water with a concentration of 43.2 ppm, which is stored in the finished product storage tank 22.

[0131] Example 3

[0132] exist Figure 1 In the illustrated embodiment, this embodiment provides a nitrogen stripping-based distillation system for producing low-deuterium water. The difference from Embodiment 1 is that the total packing height of the packing material in the first stripping tower 4 is 10m; the packing material in the first demister section 5 is 350Y type structured packing material, with a packing height accounting for 15% of the total packing height and a packing density of 120kg / m³. 3 The first mass transfer section 6 is filled with 250Y type structured packing, which accounts for 70% of the total packing height, and has a packing density of 170 kg / m³. 3 The first gas distribution section 7 is filled with 125Y type structured packing, with a filling height accounting for 15% of the total packing height and a filling density of 220 kg / m³. 3 .

[0133] The packing height in the second stripping tower 12 is 17m; the packing in the second demister section 13 is 350Y type structured packing, with a packing height accounting for 15% of the total packing height and a packing density of 120kg / m³. 3 The second mass transfer section 14 is filled with 250Y type structured packing, with a filling height accounting for 70% of the total packing height and a filling density of 170 kg / m³. 3The second gas distribution section 15 is filled with 125Y type structured packing, with a filling height accounting for 15% of the total packing height and a filling density of 220 kg / m³. 3 .

[0134] The other structures are exactly the same as in Example 1.

[0135] This embodiment also provides a production method for preparing deuterium-free water using the above-described production system, specifically including the following steps:

[0136] The raw water is passed through a multi-stage filter 2 to remove suspended particles and organic matter, and then enters an electro-deionization water device to further remove ions, resulting in high-purity water with a resistivity of 16 MΩ·cm.

[0137] High-purity water at 5m 3 A flow rate of / h is sprayed into the first stripping tower 4 from the top of the tower. At the same time, nitrogen stored in nitrogen storage tank 24 is heated to 60°C by the first gas heater 25 and then sprayed at 75m³ / h. 3 A flow rate of / h is introduced into the first stripping tower 4 from the bottom of the tower. Under an operating pressure of 7kPa and an internal temperature of 55℃, high-purity water and nitrogen gas are in countercurrent contact in the packing layer of the first stripping tower 4. The reflux ratio of the first stripping tower 4 is 6. Due to its higher boiling point, the deuterium-rich water is enriched at the bottom of the tower. The mixture of deuterium-poor water vapor and nitrogen gas is discharged from the top of the first stripping tower 4 and enters the first condenser 11. It is condensed at 7℃ to obtain condensate. Part of the deuterium-rich water collected at the bottom of the first stripping tower 4 is returned to the first reboiler 10 for recycling, and part is discharged from the first stripping tower 4.

[0138] Uncondensed nitrogen in the first condenser 11 is discharged into the circulating compressor 23. After being pressurized by the circulating compressor 23, it returns to the nitrogen storage tank 24 for reuse. The condensate obtained after condensation in the first condenser 11 is preheated to 35°C and then discharged at 2m³. 3 A flow rate of / h is sprayed into the second stripping tower 12 from the top. Simultaneously, nitrogen stored in nitrogen storage tank 24 is heated to 40°C by the second gas heater 26 and then discharged at a flow rate of 40m³ / h. 3 A flow rate of / h is introduced into the second stripping tower 12 from the bottom of the tower. Under an operating pressure of 3kPa and a tower temperature of 40℃, the condensate and nitrogen gas are in countercurrent contact in the packing layer of the second stripping tower 12. The reflux ratio of the second stripping tower 12 is 11. The deuterium-rich water is enriched at the bottom of the tower due to its higher boiling point. The mixture of deuterium-poor water vapor and nitrogen gas is discharged from the top of the second stripping tower 12 and enters the second condenser 19. It is condensed at 7℃ to obtain condensate. Part of the deuterium-rich water collected at the bottom of the second stripping tower 12 is returned to the second reboiler 18 for recycling, and part is discharged from the second stripping tower 12.

[0139] Uncondensed nitrogen in the second condenser 19 is discharged from the second condenser 19 and enters the circulating compressor 23. After being pressurized by the circulating compressor 23, it returns to the nitrogen storage tank 24 for recycling. The condensate obtained after condensation in the second condenser 19 enters the condensate storage tank 20, and then undergoes secondary condensation at 2°C by the deep condenser 21 to obtain low deuterium water with a concentration of 38.7 ppm, which is stored in the finished product storage tank 22.

[0140] Example 4

[0141] exist Figure 1 In the illustrated embodiment, this embodiment provides a nitrogen stripping-based distillation system for producing low-deuterium water. The difference from Embodiment 1 is that the total packing height of the packing material in the first stripping tower 4 is 11m; the packing material in the first demister section 5 is 350Y type structured packing material, with a packing height accounting for 18% of the total packing height and a packing density of 110kg / m³. 3 The first mass transfer section 6 is filled with 250Y type structured packing, which accounts for 64% of the total packing height, and has a packing density of 160 kg / m³. 3 The first gas distribution section 7 is filled with 125Y type structured packing, which accounts for 18% of the total packing height, and has a packing density of 210 kg / m³. 3 .

[0142] The packing height in the second stripping tower 12 is 18m; the packing in the second demister section 13 is 350Y type structured packing, with a packing height accounting for 18% of the total packing height and a packing density of 110kg / m³. 3 The second mass transfer section 14 is filled with 250Y type structured packing, which accounts for 64% of the total packing height, and has a packing density of 160 kg / m³. 3 The second gas distribution section 15 is filled with 125Y type structured packing, which accounts for 18% of the total packing height, and has a packing density of 210 kg / m³. 3 .

[0143] The other structures are exactly the same as in Example 1.

[0144] This embodiment also provides a production method for preparing deuterium-free water using the above-described production system, specifically including the following steps:

[0145] The raw water is passed through a multi-stage filter 2 to remove suspended particles and organic matter, and then enters an electro-deionization water device to further remove ions, resulting in high-purity water with a resistivity of 17 MΩ·cm.

[0146] High-purity water at 5m 3A flow rate of / h is sprayed into the first stripping tower 4 from the top of the tower. At the same time, nitrogen stored in nitrogen storage tank 24 is heated to 62°C by the first gas heater 25 and then sprayed out at a flow rate of 80m³ / h. 3 A flow rate of / h is introduced into the first stripping tower 4 from the bottom of the tower. Under an operating pressure of 8kPa and a tower temperature of 58℃, high-purity water and nitrogen gas are in countercurrent contact in the packing layer of the first stripping tower 4. The reflux ratio of the first stripping tower 4 is 6. Due to its high boiling point, the deuterium-rich water is enriched at the bottom of the tower. The mixture of deuterium-poor water vapor and nitrogen gas is discharged from the top of the first stripping tower 4 and enters the first condenser 11. It is condensed at 8℃ to obtain condensate. Part of the deuterium-rich water collected at the bottom of the first stripping tower 4 is returned to the first reboiler 10 for recycling, and part is discharged from the first stripping tower 4.

[0147] Uncondensed nitrogen in the first condenser 11 is discharged into the circulating compressor 23. After being pressurized by the circulating compressor 23, it returns to the nitrogen storage tank 24 for reuse. The condensate obtained after condensation in the first condenser 11 is preheated to 38°C and then discharged at a speed of 2.5m³. 3 A flow rate of / h is sprayed into the second stripping tower 12 from the top. Simultaneously, nitrogen stored in nitrogen storage tank 24 is heated to 42°C by the second gas heater 26 and then discharged at a rate of 45m³ / h. 3 A flow rate of / h is introduced into the second stripping tower 12 from the bottom of the tower. Under an operating pressure of 4kPa and a tower temperature of 42℃, the condensate and nitrogen gas are in countercurrent contact in the packing layer of the second stripping tower 12. The reflux ratio of the second stripping tower 12 is 10. The deuterium-rich water is enriched at the bottom of the tower due to its higher boiling point. The mixture of deuterium-poor water vapor and nitrogen gas is discharged from the top of the second stripping tower 12 and enters the second condenser 19. It is condensed at 8℃ to obtain condensate. Part of the deuterium-rich water collected at the bottom of the second stripping tower 12 is returned to the second reboiler 18 for recycling, and part is discharged from the second stripping tower 12.

[0148] Uncondensed nitrogen in the second condenser 19 is discharged from the second condenser 19 and enters the circulating compressor 23. After being pressurized by the circulating compressor 23, it returns to the nitrogen storage tank 24 for recycling. The condensate obtained after condensation in the second condenser 19 enters the condensate storage tank 20, and then undergoes secondary condensation at 3°C ​​by the deep condenser 21 to obtain low deuterium water with a concentration of 45.8 ppm, which is stored in the finished product storage tank 22.

[0149] Example 5

[0150] exist Figure 1 In the illustrated embodiment, this embodiment provides a nitrogen stripping-based distillation system for producing low-deuterium water. The difference from Embodiment 1 is that the total packing height of the packing material in the first stripping tower 4 is 12m; the packing material in the first demister section 5 is 350Y type structured packing material, with a packing height accounting for 20% of the total packing height and a packing density of 100kg / m³.3 The first mass transfer section 6 is filled with 250Y type structured packing, with a filling height accounting for 60% of the total packing height and a filling density of 150 kg / m³. 3 The first gas distribution section 7 is filled with 125Y type structured packing, with a filling height accounting for 20% of the total packing height and a filling density of 200 kg / m³. 3 .

[0151] The packing height in the second stripping tower 12 is 20m; the packing in the second demister section 13 is 350Y type structured packing, with a packing height accounting for 20% of the total packing height and a packing density of 100kg / m³. 3 The second mass transfer section 14 is filled with 250Y type structured packing, with a filling height accounting for 60% of the total packing height and a filling density of 150 kg / m³. 3 The second gas distribution section 15 is filled with 125Y type structured packing, which accounts for 20% of the total packing height, and has a packing density of 200 kg / m³. 3 .

[0152] The other structures are exactly the same as in Example 1.

[0153] This embodiment also provides a production method for preparing deuterium-free water using the above-described production system, specifically including the following steps:

[0154] The raw water is passed through a multi-stage filter 2 to remove suspended particles and organic matter, and then enters an electro-deionization water device to further remove ions, resulting in high-purity water with a resistivity of 18 MΩ·cm.

[0155] High-purity water at 6m 3 A flow rate of / h is sprayed into the first stripping tower 4 from the top of the tower. At the same time, nitrogen stored in nitrogen storage tank 24 is heated to 65°C by the first gas heater 25 and then sprayed at 90m³ / h. 3 A flow rate of / h is introduced into the first stripping tower 4 from the bottom of the tower. Under an operating pressure of 10kPa and a tower temperature of 60℃, high-purity water and nitrogen gas are in countercurrent contact in the packing layer of the first stripping tower 4. The reflux ratio of the first stripping tower 4 is 5. Due to its high boiling point, the deuterium-rich water is enriched at the bottom of the tower. The mixture of deuterium-poor water vapor and nitrogen gas is discharged from the top of the first stripping tower 4 and enters the first condenser 11. It is condensed at 10℃ to obtain condensate. Part of the deuterium-rich water collected at the bottom of the first stripping tower 4 is returned to the first reboiler 10 for recycling, and part is discharged from the first stripping tower 4.

[0156] Uncondensed nitrogen in the first condenser 11 is discharged into the circulating compressor 23. After being pressurized by the circulating compressor 23, it returns to the nitrogen storage tank 24 for reuse. The condensate obtained after condensation in the first condenser 11 is preheated to 40°C and then discharged at 3m³. 3 A flow rate of / h is sprayed into the second stripping tower 12 from the top. Simultaneously, nitrogen stored in nitrogen storage tank 24 is heated to 45°C by the second gas heater 26 and then discharged at a flow rate of 50m³ / h. 3 A flow rate of / h is introduced into the second stripping tower 12 from the bottom of the tower. Under an operating pressure of 5kPa and an internal temperature of 45℃, the condensate and nitrogen gas are in countercurrent contact in the packing layer of the second stripping tower 12. The reflux ratio of the second stripping tower 12 is 10. The deuterium-rich water is enriched at the bottom of the tower due to its higher boiling point. The mixture of deuterium-deficient water vapor and nitrogen gas is discharged from the top of the second stripping tower 12 and enters the second condenser 19. It is condensed at 10℃ to obtain condensate. Part of the deuterium-rich water collected at the bottom of the second stripping tower 12 is returned to the second reboiler 18 for recycling, and part is discharged from the second stripping tower 12.

[0157] Uncondensed nitrogen in the second condenser 19 is discharged from the second condenser 19 and enters the circulating compressor 23. After being pressurized by the circulating compressor 23, it returns to the nitrogen storage tank 24 for recycling. The condensate obtained after condensation in the second condenser 19 enters the condensate storage tank 20, and then undergoes secondary condensation at 5°C by the deep condenser 21 to obtain low deuterium water with a concentration of 47.6 ppm, which is stored in the finished product storage tank 22.

[0158] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A system for producing low deuterium water by distillation based on nitrogen stripping, characterized in that, The distillation method low deuterium water production system comprises a pretreatment unit, a gas stripping distillation unit and a product collection unit connected in sequence; The pretreatment unit comprises a raw water tank, a multi-stage filter and an electrodeionization device connected in sequence along the material flow direction; The gas stripping distillation unit comprises a first gas stripping module and a second gas stripping module connected in sequence, wherein the preliminary purified condensate discharged from the top of the first gas stripping module enters the second gas stripping module for secondary purification; The product collection unit comprises a condensate storage tank, a deep condenser and a product storage tank connected in sequence along the material flow direction.

2. The distillation method deuterium-depleted water production system according to claim 1, characterized in that, The first gas stripping module comprises a first gas stripping tower, a first condenser and a first reboiler; The top feed inlet of the first gas stripping tower is connected to the outlet of the electrodeionization device, the top gas outlet of the first gas stripping tower is connected to the inlet of the first condenser, and the bottom liquid outlet of the first gas stripping tower is connected to the inlet of the first reboiler; The second gas stripping module comprises a second gas stripping tower, a second condenser and a second reboiler, wherein the top feed inlet of the second gas stripping tower is connected to the outlet of the first condenser, the top gas outlet of the second gas stripping tower is connected to the inlet of the second condenser, and the bottom liquid outlet of the second gas stripping tower is connected to the inlet of the second reboiler; The interiors of the first gas stripping tower and the second gas stripping tower are both filled with packing, the bottoms of the first gas stripping tower and the second gas stripping tower are provided with nitrogen inlets, and the tops of the first gas stripping tower and the second gas stripping tower are respectively provided with a first mist separator and a second mist separator.

3. The distillation method deuterium-depleted water production system according to claim 2, characterized in that, The distillation method low deuterium water production system further comprises a nitrogen circulation unit; The nitrogen circulation unit comprises a nitrogen storage tank, a first gas heater, a second gas heater and a circulation compressor, the gas outlets of the first condenser and the second condenser are respectively and independently connected to the inlet of the circulation compressor, the inlet of the circulation compressor is connected to the backflow port of the nitrogen storage tank, and the outlet of the nitrogen storage tank is respectively and independently connected to the nitrogen inlets of the first gas stripping tower and the second gas stripping tower. The first gas heater is arranged on the connecting pipeline between the nitrogen storage tank and the first gas stripping tower, and the second gas heater is arranged on the connecting pipeline between the nitrogen storage tank and the second gas stripping tower.

4. The distillation method of producing low deuterium water system according to claim 3, wherein The packing in the first gas stripping tower has a packing height of 8-12 m; The packing bed in the first gas stripping tower is divided into a first demisting section, a first mass transfer section and a first gas distribution section from top to bottom; The packing in the first demisting section has a packing height accounting for 10-20% of the total packing height; The packing density of the packing of the first demisting section is 100-150 kg / m 3 ; The packing in the first mass transfer section has a packing height accounting for 60-80% of the total packing height; The packing density of the packing of the first mass transfer section is 150-200 kg / m 3 ; The packing in the first gas distribution section has a packing height accounting for 10-20% of the total packing height; The packing density of the packing of the first gas distribution section is 200-250 kg / m 3 .

5. The distillation method of producing low deuterium water according to claim 4, wherein The packing in the second gas stripping tower has a packing height of 15-20 m; The packing bed in the second gas stripping tower is divided into a second demisting section, a second mass transfer section and a second gas distribution section from top to bottom; The packing in the second demisting section has a packing height accounting for 10-20% of the total packing height; The packing density of the packing of the second demisting section is 100-150 kg / m 3 ; The packing in the second mass transfer section has a packing height accounting for 60-80% of the total packing height; The packing density of the packing of the second mass transfer section is 150-200 kg / m 3 ; The packing height of the packing of the second gas distribution section accounts for 10-20% of the total packing height; The packing density of the packing of the second gas distribution section is 200-250 kg / m 3 .

6. The distillation method of producing low deuterium water system according to claim 5, wherein, The packing filled in the first mist elimination section and the second mist elimination section is 350Y structured packing; The packing filled in the first mass transfer section and the second mass transfer section is 250Y structured packing; The packing filled in the first gas distribution section and the second gas distribution section is 125Y structured packing; First liquid redistributors are arranged between the first mist elimination section and the first mass transfer section and between the first mass transfer section and the first gas distribution section; Second liquid redistributors are arranged between the second mist elimination section and the second mass transfer section and between the second mass transfer section and the second gas distribution section.

7. A production method using the production system of the distilled low-deuterium water according to any one of claims 1 to 6, characterized by, The production method comprises: The raw water is removed of suspended particles and organic matters by the multi-stage filter, and then enters the electrodeionization water device to remove ions in depth, thereby obtaining high-purity water; The high-purity water and nitrogen gas are introduced into the first gas stripping module, and the condensed liquid preliminarily purified after nitrogen stripping is discharged from the first gas stripping module, enters the second gas stripping module after nitrogen stripping, and is discharged into the condensed liquid storage tank, and low-deuterium water is obtained after secondary condensation by the depth condenser.

8. The production method according to claim 7, characterized by, The production method specifically comprises the following steps: The raw water is removed of suspended particles and organic matters by the multi-stage filter, and then enters the electrodeionization water device to remove ions in depth, thereby obtaining high-purity water; The high-purity water is sprayed from the top of the first gas stripping column into the column, and the nitrogen gas stored in the nitrogen gas storage tank is heated by the first gas heater and introduced into the first gas stripping column from the bottom. In the negative pressure and heating environment, the high-purity water and the nitrogen gas are countercurrently contacted in the packing layer of the first gas stripping column. The deuterium-rich water is enriched to the bottom due to the higher boiling point, and the mixed gas of deuterium-poor water vapor and nitrogen gas is discharged from the top of the first gas stripping column into the first condenser. Part of the deuterium-rich water collected at the bottom of the first gas stripping column is returned to the first reboiler for recycling, and part is discharged from the first gas stripping column. The nitrogen gas that is not condensed in the first condenser is discharged from the first condenser into the circulating compressor, pressurized by the circulating compressor, and returned to the nitrogen gas storage tank for recycling. The condensed liquid obtained after condensation in the first condenser is preheated and sprayed from the top of the second gas stripping column into the column. At the same time, the nitrogen gas stored in the nitrogen gas storage tank is heated by the second gas heater and introduced into the second gas stripping column from the bottom. In the negative pressure and heating environment, the condensed liquid and the nitrogen gas are countercurrently contacted in the packing layer of the second gas stripping column. The deuterium-rich water is enriched to the bottom due to the higher boiling point, and the mixed gas of deuterium-poor water vapor and nitrogen gas is discharged from the top of the second gas stripping column into the second condenser. Part of the deuterium-rich water collected at the bottom of the second gas stripping column is returned to the second reboiler for recycling, and part is discharged from the second gas stripping column. The nitrogen gas not condensed in the second condenser is discharged from the second condenser into the circulating compressor, pressurized by the circulating compressor, and returned to the nitrogen gas storage tank for recycling. The condensed liquid obtained after condensation in the second condenser is introduced into the condensed liquid storage tank, then subjected to secondary condensation by the deep condenser to obtain low-deuterium water, which is stored in the finished product storage tank.

9. The production method according to claim 8, characterized by, The high-purity water has a resistivity of ≥18 MΩ·cm; The nitrogen gas is preheated to 55-65°C by the first gas heater and then introduced into the first gas stripping tower; The spraying amount of the high-purity water in the first stripping tower is 3-6 m 3 / h; The flow rate of the nitrogen gas in the first stripping column is 60-90 m 3 / h; The operating pressure of the first gas stripping tower is 5-10 kPa; The internal temperature of the first gas stripping tower is 50-60°C; The reflux ratio of the first gas stripping tower is 5-8; The cooling temperature of the mixed gas in the first condenser is 5-10°C.

10. The production method according to claim 8, characterized by, The condensed liquid obtained after condensation in the first condenser is preheated to 30-40°C and then introduced into the second gas stripping tower from the top of the tower by spraying; The nitrogen gas is preheated to 35-45°C by the second gas heater and then introduced into the second gas stripping tower; The spraying amount of the condensate in the second stripping tower is 1-3 m 3 / h; The flow rate of the nitrogen gas in the second stripping column is 30-50 m 3 / h; The operating pressure of the second gas stripping tower is 2-5 kPa; The internal temperature of the second gas stripping tower is 35-45°C; The reflux ratio of the second gas stripping tower is 10-12; The cooling temperature of the mixed gas in the second condenser is 5-10°C; The cooling temperature of the condensed liquid in the deep condenser is 0-5°C; The deuterium concentration of the low-deuterium water is ≤50 ppm.

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