Method for producing heavy water through water rectification based on adsorption type heat pump energy-saving system

Abstract

The invention relates to the field of heavy water production, in particular to a method for producing heavy water through water rectification based on an adsorption type heat pump energy-saving system.The method comprises the steps that raw material water is pretreated to remove impurities and then enters a heavy water enrichment section, in an enrichment rectification tower, tower top produced liquid is converted into high-grade steam through a first adsorption type heat pump system, and the high-grade steam is used for supplying heat to a first reboiler; in a heavy water purification stage, the deuterium-enriched water enters a purification rectifying tower, a tower top produced liquid is converted into high-grade steam through a second adsorption type heat pump system, the high-grade steam is used for supplying heat to a second reboiler, and the deuterium content of the high-grade steam is lower than 50 ppm; the deuterium-depleted water with the deuterium content lower than 50 ppm is produced, the tower bottom liquid of the purification rectifying tower is fed into a second reboiler to be evaporated, then part of tower bottom liquid serves as heavy water to be conveyed to a storage tank, the deuterium content is not lower than 99.9%, the deuterium extraction rate is high, the raw material water consumption is small, no three-waste emission is generated, resource utilization is achieved, and energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the field of heavy water production, and in particular to a method for producing heavy water by water rectification based on an adsorption heat pump energy-saving system. Background Art

[0002] The main methods for producing heavy water at present include hydrogen sulfide (H2S)-water dual-temperature exchange method, hydrogen-water dual-temperature exchange method, hydrogen-water exchange and electrolysis combined method and liquid hydrogen distillation method. The H2S-water dual-temperature exchange method has the advantages of not requiring the use of catalysts and low energy consumption, but due to the high toxicity of H2S, the risk of explosion, and the serious corrosion of equipment and pipelines in this method, it is gradually being eliminated; the hydrogen-water dual-temperature exchange method has a hot tower and a cold tower. In the lower hot tower, deuterium is transferred from water to hydrogen, and in the upper cold tower, deuterium is transferred from hydrogen to liquid water. Finally, heavy water is purified from deuterium-rich water by vacuum distillation. This method is similar to the H2S-water dual-temperature exchange method. Its disadvantages are that the process is long, the amount of precious metal catalysts used is too large, the investment cost is high, and hydrogen is flammable and explosive, with high safety risks; The combined method of hydrogen-water exchange and electrolysis is a single-temperature exchange method that converts water into hydrogen through electrolysis. All raw water needs to be electrolyzed, which consumes a lot of electricity and has a high production cost. The liquid hydrogen distillation method directly extracts deuterium from hydrogen by low-temperature distillation. Deuterium and oxygen burn to form heavy water. Since hydrogen has a critical point and its boiling point no longer increases after the pressure exceeds 10 atmospheres, the operating temperature of the liquid hydrogen distillation method is very low, below -247°C. This operating temperature determines that this operating method has extremely high requirements for equipment cooling. In addition, it is currently limited by the lack of large-scale refrigeration equipment at this operating temperature, making it difficult to industrialize on a large scale.

[0003] In view of the above problems, in order to make up for the deficiencies of the prior art, it is urgent to design a method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system that solves the above problems. Summary of the invention

[0004] In order to solve the problems of the prior art, the present invention provides a method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system. The method can obtain heavy water with a molar fraction of not less than 99.9%.

[0005] The object of the present invention can be achieved by the following technical scheme: A method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system comprises the following steps:

[0006] S1: Raw water pretreatment stage: tap water is sent into the pretreatment system to soften and remove impurity ions, and then enters the soft water buffer tank;

[0007] S2: Heavy water enrichment section: The water in the soft water buffer tank is sent to the middle section of the enrichment distillation tower. The top steam of the enrichment distillation tower includes two groups of routes, wherein the top produced liquid in the first route enters the first adsorption heat pump system, is converted into high-grade steam by the first adsorption heat pump system, and then supplies heat to the first reboiler. The deuterium content of the low-deuterium water after heat exchange cooling is not higher than 50ppm, and the low-deuterium water enters the first low-deuterium water finished product tank, wherein the top steam in the second route enters the multi-stage condenser of the enrichment distillation tower for condensation; the bottom liquid of the enrichment distillation tower is sent to the first reboiler for evaporation and then refluxed into the enrichment distillation tower, and part of the output is transported to the deuterium-enriched water buffer tank as deuterium-enriched water with a deuterium content of 1% to 10%;

[0008] S3: heavy water purification stage: the deuterium-rich water in the deuterium-rich water buffer tank is sent to the middle section of the purification distillation tower, and the top steam of the purification distillation tower includes two groups of routes, wherein the top produced liquid in the first route enters the second adsorption heat pump system, is converted into high-grade steam by the second adsorption heat pump system, and then supplies heat to the second reboiler, and the deuterium content of the low-deuterium water after heat exchange cooling is not higher than 50ppm, and the low-deuterium water enters the second low-deuterium water finished product tank, wherein the top steam in the second route enters the multi-stage condenser of the purification distillation tower for condensation; the bottom liquid of the purification distillation tower is sent to the second reboiler for evaporation and then refluxed into the purification distillation tower, and part of the output is transported to the heavy water storage tank as heavy water with a deuterium content of not less than 99.9%.

[0009] Further improvement, in step S2, the heavy water enrichment section includes the adsorption and desorption process of the adsorption heat pump system: the produced liquid from the top of the enrichment distillation tower enters the first low-deuterium water buffer tank, and is then transported from the bottom of the first adsorption bed in the first adsorption heat pump system to the tube side of the first adsorption bed through the fifth water pump, and then transported to the shell side through the small holes on the heat exchange tube wall of the first adsorption bed, and fully contacts with the adsorbent filled in the shell side to release a large amount of heat, and converts the low-grade waste heat into high-temperature steam as the heat source of the first reboiler, which is set as the adsorption process; the first adsorption bed is driven by 100-150°C industrial high-temperature waste gas, the high-temperature gas HWAS enters from the bottom of the first adsorption bed, and the gas HWAR after heat exchange cooling is discharged from the top of the tower to the working interface, which is set as the desorption process; in step S3 The heavy water purification stage includes adsorption and desorption processes of the adsorption heat pump system: the produced liquid from the top of the purification distillation tower enters the second low-deuterium water buffer tank, and is then transported from the bottom of the second adsorption bed in the second adsorption heat pump system to the tube side of the second adsorption bed through the sixth water pump, and then transported to the shell side through the small holes on the heat exchange tube wall of the second adsorption bed, and fully contacts with the adsorbent filled in the shell side to release a large amount of heat, and converts the low-grade waste heat into high-temperature steam as the heat source of the second reboiler, which is set as an adsorption process; the second adsorption bed is driven by 100-150°C industrial high-temperature waste gas, the high-temperature gas HWAS enters from the bottom of the second adsorption bed, and the gas HWAR after heat exchange cooling is discharged from the top of the tower to the working interface, which is set as a desorption process, and the first adsorption bed and the second adsorption bed each include two groups.

[0010] As a further improvement, the soft water in the soft water buffer tank is transported into the middle section of the enrichment distillation tower by the first water pump, and the bottom liquid of the enrichment distillation tower is pressurized by the second water pump and partially sent to the first reboiler for evaporation and then refluxed into the enrichment distillation tower; the deuterium-enriched water in the deuterium-enriched water buffer tank is transported into the middle section of the purification distillation tower by the third water pump, and the bottom liquid of the purification distillation tower is pressurized by the fourth water pump and partially sent to the second reboiler for evaporation and then refluxed into the purification distillation tower.

[0011] As a further improvement, the multi-stage condenser of the enriching distillation tower includes a first-stage condenser at the top of the enriching tower and a second-stage condenser at the top of the enriching tower, and the top steam in the second route enters the first-stage condenser at the top of the enriching tower and then enters the second-stage condenser at the top of the enriching tower again, and the rear end of the second-stage condenser at the top of the enriching tower is connected to the first vacuum buffer tank and the first vacuum pump in sequence; the multi-stage condenser of the purifying distillation tower includes a first-stage condenser at the top of the purification tower and a second-stage condenser at the top of the purification tower, and the top steam in the second route enters the second-stage condenser at the top of the purification tower and then enters the second-stage condenser at the top of the purification tower again, and the rear end of the second-stage condenser at the top of the purification tower is connected to the second vacuum buffer tank and the second vacuum pump in sequence.

[0012] As a further improvement, the enrichment distillation tower can be used in series in groups of 2 to 10, and the purification distillation tower can be used in series in groups of 2 to 10.

[0013] As a further improvement, the set pressure of the enrichment distillation tower is 8 to 15 kPa, and the set pressure of the purification distillation tower is 8 to 15 kPa.

[0014] As a further improvement, the soft water buffer tank is electrically heated and insulated, and the heating and insulation temperature range is 50-70°C; the deuterium-enriched water buffer tank is electrically heated and insulated, and the heating and insulation temperature range is 50-70°C. The first low-deuterium water finished product tank, the second low-deuterium water finished product tank and the heavy water storage tank are electrically heated and insulated, and the heating and insulation temperature is not less than 5°C.

[0015] As a further improvement, the adsorbent in the first adsorption heat pump system and the second adsorption heat pump system is one or more of activated carbon, zeolite, metal oxide, and metal skeleton material.

[0016] Compared with the prior art, the method for producing heavy water by water distillation based on the adsorption heat pump energy-saving system of the present invention has the following beneficial effects:

[0017] Taking advantage of the fact that the separation coefficient of light water and heavy water increases with decreasing pressure, the vacuum distillation method is adopted to have a high separation coefficient at low pressure, and the heavy water product is obtained through a two-stage distillation process of enrichment and purification; at the same time, the adsorption heat pump distillation technology is used for the two-stage distillation respectively, and the waste heat of low-temperature and low-deuterium water at the top of the tower is recovered and converted into high-grade steam for heating the bottom of the tower. The desorption process is driven by industrial high-temperature exhaust gas, which realizes the effective utilization of resources and greatly reduces the energy consumption of the distillation process; at the same time, the raw water uses tap water, and the heavy water product is prepared by the two-stage water distillation method based on the adsorption heat pump energy-saving system, with a high deuterium extraction rate, a small amount of raw water, a high added value of the product, no three wastes discharged, no flammable and explosive substances, and safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The process flow chart of the present invention is

[0019] Figure 2 The process flow chart of the adsorption heat pump system in the present invention is

[0020] In the figure, 101-pretreatment system, 102-soft water buffer tank, 201-first water pump, 202-enrichment distillation tower, 203-first condenser at the top of the enrichment tower, 204-secondary condenser at the top of the enrichment tower, 205-first vacuum buffer tank, 206-second vacuum pump, 207-first adsorption heat pump system, 208-first low-deuterium water buffer tank, 209-fifth water pump, 210-first reboiler, 211-second water pump, 212-deuterium-enriched water buffer tank, 301-third water pump, 302- 02-purification distillation tower, 303-first-stage condenser at the top of purification tower, 304-second-stage condenser at the top of purification tower, 305-second vacuum buffer tank, 306-second vacuum pump, 307-second adsorption heat pump system, 308-second low-deuterium water buffer tank, 309-sixth water pump, 310-second reboiler, 311-fourth water pump, 312-heavy water storage tank, 313-second low-deuterium water finished product tank, 314-first low-deuterium water finished product tank, 315-first adsorption bed, 316-second adsorption bed. DETAILED DESCRIPTION

[0021] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] Below is a combination of the embodiments and the attached Figures 1-2 , the technical solution of the present invention is further elaborated.

[0024] Example 1

[0025] A method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system comprises the following steps:

[0026] S1: Raw water pretreatment stage: tap water is sent to the pretreatment system 101 to be softened and impurity ions are removed, and then enters the soft water buffer tank 102;

[0027] S2: heavy water enrichment section: the water in the soft water buffer tank 102 is sent to the middle section of the enrichment distillation tower 202. The top steam of the enrichment distillation tower 202 includes two groups of routes, wherein the top produced liquid in the first route enters the first adsorption heat pump system 207, is converted into high-grade steam by the first adsorption heat pump system 207, and then supplies heat to the first reboiler 210. The deuterium content of the low-deuterium water after heat exchange cooling is not higher than 50ppm, and the low-deuterium water enters the first low-deuterium water finished product tank 314. The top steam in the second route enters the multi-stage condenser of the enrichment distillation tower 202 for condensation; the bottom liquid of the enrichment distillation tower 202 is sent to the first reboiler 210 for evaporation and then refluxed into the enrichment distillation tower 202. Part of the output is transported to the deuterium-enriched water buffer tank 212 as deuterium-enriched water with a deuterium content of 1% to 10%;

[0028] S3: heavy water purification stage: the deuterium-rich water in the deuterium-rich water buffer tank 212 is sent to the middle section of the purification distillation tower 302, and the top steam of the purification distillation tower 302 includes two groups of routes, wherein the top produced liquid in the first route enters the second adsorption heat pump system 307, is converted into high-grade steam by the second adsorption heat pump system 307, and then supplies heat to the second reboiler 310, and the deuterium content of the low-deuterium water after heat exchange cooling is not higher than 50ppm, and the low-deuterium water enters the second low-deuterium water finished product tank 313, wherein the top steam in the second route enters the multi-stage condenser of the purification distillation tower 302 for condensation; the bottom liquid of the purification distillation tower 302 is sent to the second reboiler 310 for evaporation and then refluxed into the purification distillation tower 302, and part of the output is transported to the heavy water storage tank 312 as heavy water with a deuterium content of not less than 99.9%.

[0029] As a further preferred embodiment, in step S2, the heavy water enrichment section includes an adsorption and desorption process of an adsorption heat pump system: the produced liquid from the top of the enrichment distillation tower 202 enters the first low-deuterium water buffer tank 208, and is then transported from the bottom of the first adsorption bed 315 in the first adsorption heat pump system 207 to the tube side of the first adsorption bed 315 through the fifth water pump 209, and then transported to the shell side through the small holes on the heat exchange tube wall of the first adsorption bed 315, and fully contacts with the adsorbent loaded in the shell side to release a large amount of heat, and converts the low-grade waste heat into high-temperature steam as the heat source of the first reboiler 210, which is set as an adsorption process; the first adsorption bed 315 is driven by 100-150°C industrial high-temperature waste gas, and the high-temperature gas HWAS enters from the bottom of the first adsorption bed 315, and the gas HWAR after heat exchange cooling is discharged from the top of the tower to the working interface, which is set as a desorption process; in step S3 The heavy water purification stage includes adsorption and desorption processes of the adsorption heat pump system: the produced liquid from the top of the purification distillation tower 302 enters the second low-deuterium water buffer tank 308, and is then transported from the bottom of the second adsorption bed 316 in the second adsorption heat pump system 307 to the tube side of the second adsorption bed 316 through the sixth water pump 309, and then transported to the shell side through the small holes on the heat exchange tube wall of the second adsorption bed 316, and fully contacts with the adsorbent filled in the shell side to release a large amount of heat, and converts the low-grade waste heat into high-temperature steam as the heat source of the second reboiler 310, which is set as an adsorption process; the second adsorption bed 316 is driven by 100-150°C industrial high-temperature waste gas, the high-temperature gas HWAS enters from the bottom of the second adsorption bed 316, and the gas HWAR after heat exchange cooling is discharged from the top of the tower. The working interface is set as a desorption process, and the first adsorption bed 315 and the second adsorption bed 316 each include two groups. The adsorbent in the adsorption bed is in contact with the produced liquid at the top of the tower, releasing heat and converting low-grade waste heat into high-temperature steam as the heat source of the reboiler. The desorption process is driven by industrial high-temperature exhaust gas. The adsorption bed is heated by high-temperature gas and then discharges cooling gas, which improves the utilization efficiency of thermal energy, reduces the consumption of external energy, and realizes the effective recovery and utilization of low-grade waste heat.

[0030] As a further preferred embodiment, the soft water in the soft water buffer tank 102 is transported into the middle section of the enrichment distillation tower 202 by the first water pump 201, and the bottom liquid of the enrichment distillation tower 202 is pressurized by the second water pump 211 and partially sent to the first reboiler 210 for evaporation and then refluxed into the enrichment distillation tower 202; the deuterium-enriched water in the deuterium-enriched water buffer tank 212 is transported into the middle section of the purification distillation tower 302 by the third water pump 301, and the bottom liquid of the purification distillation tower 302 is pressurized by the fourth water pump 311 and partially sent to the second reboiler 310 for evaporation and then refluxed into the purification distillation tower 302.

[0031] As a further preferred embodiment, the multi-stage condenser of the enriching distillation tower 202 includes a first-stage condenser 203 at the top of the enriching tower and a second-stage condenser 204 at the top of the enriching tower. In the second route, the top steam enters the first-stage condenser 203 at the top of the enriching tower and then enters the second-stage condenser 204 at the top of the enriching tower again. The rear end of the second-stage condenser 204 at the top of the enriching tower is sequentially connected to the first vacuum buffer tank 205 and the first vacuum pump 206, which improves the condensation efficiency, ensures the low-pressure operation of the distillation tower, and improves the separation effect; the multi-stage condenser of the purifying distillation tower 302 includes a first-stage condenser 303 at the top of the purifying tower and a second-stage condenser 304 at the top of the purifying tower. In the second route, the top steam enters the second-stage condenser 303 at the top of the purifying tower and then enters the second-stage condenser 304 at the top of the purifying tower again. The rear end of the second-stage condenser 304 at the top of the purifying tower is sequentially connected to the second vacuum buffer tank 305 and the second vacuum pump 306, which improves the condensation efficiency, ensures the low-pressure operation of the purification tower, and improves the separation effect.

[0032] As a further preferred embodiment, the enrichment distillation tower 202 can be used in series by 2 to 10 groups, and the purification distillation tower 302 can be used in series by 2 to 10 groups. By using multiple groups of distillation towers in series, the separation effect of distillation is increased.

[0033] As a further preferred embodiment, the set pressure of the enrichment distillation tower 202 is 8-15 kPa, and the set pressure of the purification distillation tower 302 is 8-15 kPa. By setting an appropriate operating pressure, the separation coefficient of the distillation tower is optimized, the separation efficiency of light water and heavy water is improved, and the production of high-purity heavy water is ensured.

[0034] As a further preferred embodiment, the soft water buffer tank 102 is electrically heated and insulated, and the heating and insulation temperature range is 50-70°C; the deuterium-enriched water buffer tank 212 is electrically heated and insulated, and the heating and insulation temperature range is 50-70°C. The first low-deuterium water finished product tank 314, the second low-deuterium water finished product tank 313 and the heavy water storage tank 312 are electrically heated and insulated, and the heating and insulation temperature is not less than 5°C. Through electric heating and insulation, the temperature of the water in the buffer tank is kept within the set range, preventing temperature fluctuations from affecting the distillation process, ensuring the stability of the distillation process, and improving the distillation efficiency.

[0035] As a further preferred embodiment, the adsorbent in the first adsorption heat pump system 207 and the second adsorption heat pump system 307 is one or more of activated carbon, zeolite, metal oxide, and metal skeleton material. The above materials can be used as adsorbents in the adsorption heat pump system, and their adsorption capacity for specific gas molecules can be used to achieve the storage and release of thermal energy, thereby improving the efficiency of the heat pump system.

[0036] Basic principles of the present invention:

[0037] Source of raw water: tap water is sent to the pretreatment system 101 to be softened and impurity ions are removed, and then enters the soft water buffer tank 102;

[0038] Deuterium-enriched water by vacuum distillation: The soft water in the soft water buffer tank 102 is transported into the middle section of the enrichment distillation tower 202 by the first water pump 201. The first condenser 203 and the second condenser 204 at the top of the enrichment tower are used during startup. The steam at the top of the enrichment tower enters the condensation, and the operating pressure is maintained by the first vacuum buffer tank 205 and the second vacuum pump 206 at the rear end. The produced liquid at the top of the enrichment distillation tower 202 enters the first low-deuterium water buffer tank 208, and then is transported by the fifth water pump 209. After being converted into high-grade steam in the first adsorption heat pump system 207, it supplies heat to the first reboiler 210. The deuterium content of the low-deuterium water after heat exchange cooling is not higher than 50ppm. The low-deuterium water enters the first low-deuterium water finished product tank 314. The bottom liquid of the enrichment distillation tower 202 is pressurized by the second water pump 211 and partially sent to the first reboiler 210 for evaporation and then refluxed to the enrichment distillation tower 202. Part of the output is transported to the deuterium-enriched water buffer tank 212 as deuterium-enriched water with a deuterium content of 1% to 10%;

[0039] Purify heavy water by vacuum distillation: The water in the soft water buffer tank 102 is transported into the middle section of the purification distillation tower 302 by the third water pump 301. The primary condenser 203 and the secondary condenser 204 at the top of the enrichment tower are used during start-up. The steam at the top of the purification tower enters the condensation and is maintained at the operating pressure by the second vacuum buffer tank 305 and the second vacuum pump 306 at the rear end. The produced liquid at the top of the purification distillation tower 303 enters the second low-deuterium water buffer tank 308 and is then pumped from the first low-deuterium water buffer tank 309 by the sixth water pump 309. The second adsorption heat pump system 307 converts the steam into high-grade steam and supplies heat to the second reboiler 310. The deuterium content of the low-deuterium water after heat exchange cooling is not higher than 50 ppm. The low-deuterium water enters the second low-deuterium water finished product tank 313. The bottom liquid of the purification distillation tower 302 is pressurized by the fourth water pump 311 and partially sent to the second reboiler 310 for evaporation and then refluxed into the purification distillation tower 302. Part of the output is transported to the heavy water storage tank 312 as heavy water with a deuterium content of not less than 99.9%.

[0040] The continuous steam production process can be achieved by switching between two beds.

[0041] The present invention adopts a two-stage water distillation method based on adsorption heat pump technology to produce heavy water, and its characteristics are:

[0042] 1. The present invention produces heavy water by a two-stage distillation method. The two-stage water distillation method based on the adsorption heat pump energy-saving system produces heavy water. Compared with hydrogen sulfide exchange and electrolysis, the raw water of the present invention uses tap water, the product is heavy water, there is no three wastes discharge and treatment, no environmental protection cost and pressure, safety and reliability, etc., and the cost of producing heavy water by this method is low, the product value is high, and the investment recovery is fast;

[0043] 2. The use of adsorption heat pump energy-saving system greatly reduces the energy consumption of heavy water products produced by water distillation;

[0044] 3. The production process is greatly shortened, with only one pretreatment stage, one distillation enrichment stage and one distillation purification stage. On the one hand, it saves a lot of construction investment, and on the other hand, the short process makes the production operation simpler.

[0045] The embodiment is produced according to the above method, and the comparative example is ordinary distillation, and the refrigerant and the heat medium are both from outside the system. The specific process parameters of the embodiment and the comparative example are shown in Table 1, and the deuterium abundance and energy consumption of the raw materials and products are shown in Table 2

[0046] Table 1 Process conditions of each tower

[0047]

[0048] Table 2 Deuterium abundance and energy consumption

[0049]

[0050]

[0051] It can be seen from Table 1 that the operating pressure is relatively low (8-15 kPa), which is beneficial to improving the separation coefficient of light water and heavy water. The tower top temperature in the embodiment is relatively low (42-55° C.), which is beneficial to reducing energy consumption. The product recovery rate and reflux ratio in the embodiment are moderate, ensuring efficient separation.

[0052] It can be found from Table 2 that the deuterium abundance of the raw water in all embodiments and comparative examples is 150ppm, the molar fraction of low-deuterium water in the embodiments is higher, and the separation effect is better; the molar fraction of heavy water in the embodiments is close to or exceeds 99.9%, and the purification effect is significant; the consumption of circulating water and steam in the embodiments is significantly lower than that in the comparative example, and the energy-saving effect is significant.

[0053] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system, characterized in that: The following steps are involved: S1: Raw water pretreatment stage: tap water is sent into the pretreatment system to soften and remove impurity ions, and then enters the soft water buffer tank; S2: Heavy water enrichment section: The water in the soft water buffer tank is sent to the middle section of the enrichment distillation tower. The top steam of the enrichment distillation tower includes two groups of routes, wherein the top produced liquid in the first route enters the first adsorption heat pump system, is converted into high-grade steam by the first adsorption heat pump system, and then supplies heat to the first reboiler. The deuterium content of the low-deuterium water after heat exchange cooling is not higher than 50ppm, and the low-deuterium water enters the first low-deuterium water finished product tank, wherein the top steam in the second route enters the multi-stage condenser of the enrichment distillation tower for condensation; the bottom liquid of the enrichment distillation tower is sent to the first reboiler for evaporation and then refluxed into the enrichment distillation tower, and part of the output is transported to the deuterium-enriched water buffer tank as deuterium-enriched water with a deuterium content of 1% to 10%; S3: heavy water purification stage: the deuterium-rich water in the deuterium-rich water buffer tank is sent to the middle section of the purification distillation tower, and the top steam of the purification distillation tower includes two groups of routes, wherein the top produced liquid in the first route enters the second adsorption heat pump system, is converted into high-grade steam by the second adsorption heat pump system, and then supplies heat to the second reboiler, and the deuterium content of the low-deuterium water after heat exchange cooling is not higher than 50ppm, and the low-deuterium water enters the second low-deuterium water finished product tank, wherein the top steam in the second route enters the multi-stage condenser of the purification distillation tower for condensation; the bottom liquid of the purification distillation tower is sent to the second reboiler for evaporation and then refluxed into the purification distillation tower, and part of the output is transported to the heavy water storage tank as heavy water with a deuterium content of not less than 99.9%.

2. The method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system according to claim 1, characterized in that: In step S2, the heavy water enrichment section includes the adsorption and desorption process of the adsorption heat pump system: the produced liquid from the top of the enrichment distillation tower enters the first low-deuterium water buffer tank, and is then transported from the bottom of the first adsorption bed in the first adsorption heat pump system to the tube side of the first adsorption bed through the fifth water pump, and then transported to the shell side through the small holes on the heat exchange tube wall of the first adsorption bed, and fully contacts with the adsorbent filled in the shell side to release a large amount of heat, and converts the low-grade waste heat into high-temperature steam as the heat source of the first reboiler, which is set as the adsorption process; the first adsorption bed is driven by 100-150°C industrial high-temperature waste gas, the high-temperature gas HWAS enters from the bottom of the first adsorption bed, and the gas HWAR after heat exchange cooling is discharged from the top of the tower to the working interface, which is set as the desorption process; in step S3, the heavy water extraction The pure stage includes the adsorption and desorption process of the adsorption heat pump system: the produced liquid from the top of the purification distillation tower enters the second low-deuterium water buffer tank, and is then transported from the bottom of the second adsorption bed in the second adsorption heat pump system to the tube side of the second adsorption bed through the sixth water pump, and then transported to the shell side through the small holes on the heat exchange tube wall of the second adsorption bed, and fully contacts with the adsorbent filled in the shell side to release a large amount of heat, and converts the low-grade waste heat into high-temperature steam as the heat source of the second reboiler, which is set as the adsorption process; the second adsorption bed is driven by 100-150°C industrial high-temperature waste gas, the high-temperature gas HWAS enters from the bottom of the second adsorption bed, and the gas HWAR after heat exchange cooling is discharged from the top of the tower to the working interface, which is set as the desorption process, and the first adsorption bed and the second adsorption bed each include two groups.

3. The method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system according to claim 1, characterized in that: The soft water in the soft water buffer tank is transported into the middle section of the enrichment distillation tower by the first water pump, and the bottom liquid of the enrichment distillation tower is pressurized by the second water pump and partially sent to the first reboiler for evaporation and then refluxed into the enrichment distillation tower; the deuterium-enriched water in the deuterium-enriched water buffer tank is transported into the middle section of the purification distillation tower by the third water pump, and the bottom liquid of the purification distillation tower is pressurized by the fourth water pump and partially sent to the second reboiler for evaporation and then refluxed into the purification distillation tower.

4. The method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system according to claim 1, characterized in that: The multi-stage condenser of the enriching distillation tower includes a first-stage condenser at the top of the enriching tower and a second-stage condenser at the top of the enriching tower. In the second route, the top steam enters the first-stage condenser at the top of the enriching tower and then enters the second-stage condenser at the top of the enriching tower again. The rear end of the second-stage condenser at the top of the enriching tower is sequentially connected to a first vacuum buffer tank and a first vacuum pump; the multi-stage condenser of the purifying distillation tower includes a first-stage condenser at the top of the purifying tower and a second-stage condenser at the top of the purifying tower. In the second route, the top steam enters the second-stage condenser at the top of the purifying tower and then enters the second-stage condenser at the top of the purifying tower again. The rear end of the second-stage condenser at the top of the purifying tower is sequentially connected to a second vacuum buffer tank and a second vacuum pump.

5. The method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system according to claim 1, characterized in that: The enrichment distillation towers can be used in series in groups of 2 to 10, and the purification distillation towers can be used in series in groups of 2 to 10.

6. The method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system according to claim 1, characterized in that: The set pressure of the enrichment distillation tower is 8-15 kPa, and the set pressure of the purification distillation tower is 8-15 kPa.

7. The method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system according to claim 1, characterized in that: The soft water buffer tank adopts electric heating and heat preservation, and the heating and heat preservation temperature range is 50-70°C; the deuterium-enriched water buffer tank adopts electric heating and heat preservation, and the heating and heat preservation temperature range is 50-70°C. The first low-deuterium water finished product tank, the second low-deuterium water finished product tank and the heavy water storage tank adopt electric heating and heat preservation, and the heating and heat preservation temperature is not less than 5°C.

8. The method for producing heavy water by water distillation based on an adsorption heat pump energy-saving system according to claim 1, characterized in that: The adsorbent in the first adsorption heat pump system and the second adsorption heat pump system is one or more of activated carbon, zeolite, metal oxide, and metal skeleton material.

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