A system for removing deuterium and tritium from nuclear industrial wastewater and a method for removing deuterium and tritium from nuclear industrial wastewater by membrane treatment

Abstract

The present invention provides a system for removing deuterium and tritium from nuclear industrial wastewater and a method for removing deuterium and tritium from nuclear industrial wastewater by membrane treatment using the system. A membrane evaporation unit and a membrane condensation unit are designed, and the hot nuclear water containing deuterium and tritium waiting to be treated enters the membrane evaporation unit, so that it is exchanged with dry cold air, and the light components in the water to be treated pass through the membrane to achieve light component separation and deuterium and tritium concentration. The treatment temperature is greatly reduced, and multi-stage multi-effect pressure-reducing purge membrane evaporation and membrane condensation are achieved to meet the needs of practical applications.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment in nuclear industry, and in particular relates to a method for removing deuterium or tritium from nuclear industry waste water by membrane method. Background Art

[0002] Tritium in pressurized water reactor nuclear power plants is mainly produced in nuclear reactions. A part of it is produced in the fuel element and penetrates into the primary circuit through the cladding, and the other part is formed by the activation of trace impurities such as boron and lithium in the primary circuit coolant with neutrons. Tritium exists in the wastewater in the form of tritiated water (HTO). For example, taking the tritium-containing wastewater of pressurized water reactor nuclear power plants as an example, the tritium activity of the tritium-containing wastewater to be treated is 10 7 Bq / L; the concentration of tritium water is 4×10 -5 mg / L-1×10 -4 mg / L; in addition, the TDS (total dissolved solids) of other salts is 2-5 mg / L, the radioactivity concentration of non-tritium nuclides is less than 100 Bq / L, and the actual treatment capacity required is 1000m 3 / a. If the decontamination factor of tritium in tritium treatment equipment is 10-1000, it can meet the utilization and discharge requirements. With the expansion of nuclear power, the issue of tritium-containing wastewater discharge has gradually received more and more attention.

[0003] Due to the lack of treatment equipment for tritium-containing wastewater in the existing nuclear industry, and the fact that conventional radioactive nuclide removal methods such as adsorption, filtration, evaporation, ion exchange, and common membrane technology are almost impossible to separate HTO from H2O, most of the tritium is eventually discharged into the environment. The tritium emission problem will become an important constraint on the expansion or approval of this site or similar sites.

[0004] Membrane distillation technology combines the advantages of membrane technology and low-temperature volatilization technology. In the process, the hydrophobic microporous membrane acts as a separation barrier to separate the high-temperature feed liquid and the low-temperature permeate. Membrane distillation is a heat-driven separation process. Due to the temperature gradient on both sides of the membrane, a certain vapor pressure difference is generated. The water vapor molecules in the feed liquid to be treated use the vapor pressure difference as a driving force to pass through the hydrophobic microporous membrane and enter the other side of the membrane, directly or indirectly contacting the condensate, thereby achieving the purpose of separation. In the membrane distillation process, the feed liquid is in direct contact with the membrane, and the steam molecules are in direct or indirect contact with the other side of the membrane after passing through the membrane pores. According to the collection method of the permeate side steam, the membrane distillation process is divided into the following categories: direct contact membrane distillation (DCMD), vacuum membrane distillation (VMD), air gap membrane distillation (AGMD), and sweeping gas membrane distillation (SGMD). Various membrane distillation technologies have problems such as easy wetting and contamination of the membrane, low membrane thermal efficiency, and high membrane cost. In the prior art, the operating temperature is too high, which easily leads to the melting of the glue used to make the membrane element, resulting in leakage of the membrane element. Despite the nearly 80 years of development of membrane distillation and the efforts of a large number of research institutions and production companies, there are still no successful large-scale industrial membrane distillation application projects worldwide.

[0005] At present, there are no patents for using vacuum membrane distillation to remove tritium at home and abroad. Membrane distillation is mainly used for seawater desalination, chemical high-salt wastewater, concentration of fluorosilicic acid and sulfuric acid, preparation of distilled water, methanol and ethylene glycol and other substances. For example, patent number CN102989322A is a flat membrane assembly that can be used for microwave vacuum membrane distillation operation to separate calcium sulfate and humic acid. The assembly is a plate membrane, which has a smaller surface area than a roll vacuum membrane and has a lower processing efficiency. CN101205086A is a seawater desalination and concentrated salt water vacuum membrane distillation process. Although the patent uses a roll membrane, it does not mention that after long-term use of the membrane, the hydrophobic membrane is wetted, resulting in a decrease in evaporation efficiency. Patent CN 113731178 A is an air-sweeping membrane distillation system using series feeding, and the steam leaves the membrane assembly through the carrier gas purge. Patent CN103803669A is an air-sweeping vacuum membrane distillation device for brackish water and seawater and its desalination method. The patent uses an additional air purge step to use air to carry out water vapor. The air sweeping method is only used to remove the steam, but it does not solve the problem of membrane wetting. This patent research combines the roll vacuum membrane with the heat pump air sweeping method to remove the difficult-to-separate substance - tritium. It solves the problem of hydrophobic membrane wetting causing the efficiency to decrease, and uses a simple way to clean and restore the membrane efficiency. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a membrane evaporation unit and a membrane condensation unit designed for a nuclear industrial wastewater detritium removal system, which improves the thermal efficiency of the membrane element. The traditional membrane distillation process is decomposed into membrane evaporation and membrane condensation, which maintains the advantages of the original membrane distillation and avoids the fundamental cause of the decline in overall heat transfer efficiency in the traditional membrane distillation process, that is, the low heat transfer coefficient of the gas side of the membrane element; the combination of decompression and purge, and the adoption of a more efficient membrane condensation technology, increase the heat transfer coefficient of the gas side by more than one order of magnitude, and greatly improve the overall thermal efficiency. It also avoids the occurrence of membrane pollution and water permeability caused by the double-sided contact between the material and the membrane. At the same time, a full membrane distillation process without a metal heat exchanger is realized, which makes the total weight of the equipment smaller and the secondary pollution caused by the equipment lower. The detritium removal system using multi-channel rolled membrane elements and multi-stage multi-effect decompression purge membrane evaporation condensation can achieve the advantages of low flow, high turbulence, high packing density, low commissioning cost and no leakage, providing a technical basis for membrane detritium removal.

[0007] The object of the present invention is to provide a method for removing deuterium and tritium from nuclear industrial wastewater by membrane treatment, wherein the method is carried out using a nuclear industrial wastewater detritium removal system.

[0008] The method separates water containing heavy hydrogen isotopes or water containing heavy oxygen isotopes from nuclear industrial wastewater, wherein the nuclear industrial wastewater contains water containing two or more hydrogen isotopes or contains 18 O isotope of water.

[0009] The thermonuclear industrial wastewater to be treated is injected into the hot water tank of the nuclear industrial wastewater deuterium and tritium removal system. During treatment, the hot water pump is started to pump the nuclear industrial wastewater into the hot side inlet of the membrane evaporation component.

[0010] At the same time, start the vacuum pump to suck the air in the cold water tank and inject it into the air storage tank, forming a negative pressure in the cold water tank. The gas discharge valve at the outlet of the air storage tank opens, allowing the gas to enter the cold side inlet of the membrane evaporation module.

[0011] At this time, there are thermonuclear industrial wastewater and dry cold air on both sides of the membrane of the membrane evaporation component, and the heat and light water molecules of the thermonuclear industrial wastewater are exchanged to the dry cold air through the membrane.

[0012] The nuclear industry wastewater detritiation system comprises a membrane evaporation unit, a membrane condensation unit, a gas circulation unit, and a cold and hot water energy conversion unit.

[0013] The membrane evaporation unit comprises a membrane evaporation component, a hot water pump and a hot water tank, and the tritium-containing wastewater to be treated is injected into the hot water tank.

[0014] The membrane condensation unit comprises a cold water tank, a cold water pump and a membrane condensation component.

[0015] The membrane evaporation component is a single membrane element or a plurality of membrane elements, and the membrane element is a rolled membrane element.

[0016] The film evaporation component comprises a film evaporation component hot side inlet, a film evaporation component hot side outlet, a film evaporation component cold side inlet, and a film evaporation component cold side outlet.

[0017] The membrane condensation component is a single membrane element or a plurality of membrane elements, and the membrane element is a hollow membrane element.

[0018] The membrane condensation component comprises a membrane condensation component hot side inlet, a membrane condensation component hot side outlet, a membrane condensation component cold side inlet, and a membrane condensation component cold side outlet.

[0019] In the membrane evaporation assembly, the temperature of the thermonuclear industrial wastewater side is 30-90°C.

[0020] In the membrane condensation assembly, the temperature of the cold water side is 5-30°C.

[0021] In the membrane evaporation assembly, the flow velocity on the membrane surface is 1-5 m / s.

[0022] In the membrane condensation assembly, the flow velocity on the membrane surface is 1-5 m / s.

[0023] When the nuclear industrial wastewater detritiation system is started, the starting flow rate does not exceed 0.5m / s and the operating time is not shorter than 30min.

[0024] The method uses two or more hydrogen isotope waters selected from hydrogen-deuterium water, hydrogen-tritium water, deuterium-tritium water, hydrogen-protium water, deuterium-tritium water and tritium-containing water as influent water to separate hydrogen isotope water with a smaller molecular weight from heavy hydrogen isotope water, or uses hydrogen-deuterium water as influent water. 18 O water is used as the inlet water to separate the oxygen isotope water with smaller molecular weight from the heavy oxygen isotope water, including protium, deuterium, tritium and 18 O makes up water molecules.

[0025] The present invention also aims to provide a nuclear industry wastewater deuterium and tritium removal system, which includes a membrane evaporation unit, a membrane condensation unit, a gas circulation unit, and a cold and hot water energy conversion unit.

[0026] The membrane evaporation unit comprises a membrane evaporation component, a hot water pump and a hot water tank.

[0027] The membrane condensation unit comprises a cold water tank, a cold water pump and a membrane condensation component.

[0028] The gas circulation unit comprises a gas storage tank, a vacuum pump and a gas exhaust valve.

[0029] The cold and hot water energy conversion unit includes a heat pump.

[0030] The present invention has the following beneficial effects:

[0031] (1) The present invention is based on the multi-stage multi-effect vacuum-purging membrane evaporation and membrane condensation technology, and aims at the problem of the harm of highly radioactive tritium-containing nuclide solutions in the nuclear industry, especially the tritium-containing wastewater in nuclear power, to human health and the ecological environment. It breaks through the technical difficulties such as high cost, low efficiency and difficult operation and maintenance, and develops a new multi-stage multi-effect vacuum-purging membrane evaporation and condensation tritium removal system. The system has the advantages that the flow medium is all polymer material, the secondary pollution rate is low; the operating temperature is lower than 100°C, the operating energy consumption is low; the device is miniaturized, and the operation and maintenance are highly automatic.

[0032] (2) In the prior art, the operating temperature is too high, which easily causes the glue used to make the membrane element to melt, resulting in leakage of the membrane element. The present invention significantly reduces the operating temperature and avoids the above problem.

[0033] (3) The system of the present invention has the advantages of miniaturization and highly automated operation and maintenance.

[0034] (4) The roll-type membrane element used in the present invention is designed with a large opening to increase the water output and to flush out as much impurities as possible remaining in the membrane bag or inside the pipeline, thereby avoiding problems such as waterway blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of the structure of a nuclear industry wastewater detritium removal system according to the present invention is shown;

[0036] Figure 2 A schematic diagram of the rolled four-channel membrane structure in Example 2 of the present invention is shown.

[0037] Description of Figure Numbers

[0038] 1- Membrane evaporation unit;

[0039] MD-membrane evaporation module;

[0040] BLh-hot water pump;

[0041] TLh - hot water tank;

[0042] Kdh1-inlet of hot side of membrane evaporation module;

[0043] Kdh0-hot side outlet of membrane evaporation module;

[0044] Kdc1 - cold side inlet of membrane evaporation module;

[0045] Kdc0- cold side outlet of membrane evaporation module;

[0046] 2-Membrane condensation unit;

[0047] TLc-cold water tank;

[0048] BLc-cold water pump;

[0049] MC-membrane condensation module;

[0050] Kch1-hot side inlet of membrane condensation module;

[0051] Kch0-hot side outlet of membrane condensation module;

[0052] Kcc1-cold side inlet of membrane condensation module;

[0053] Kcc0-cold side outlet of membrane condensation module;

[0054] 3- Gas circulation unit;

[0055] TG-gas tank;

[0056] Bg-vacuum pump;

[0057] VG-gas discharge valve;

[0058] 4-cold and hot water energy conversion unit;

[0059] ER-heat pump;

[0060] Keh1-heat pump hot side inlet;

[0061] Keh0-heat pump hot side outlet;

[0062] Kec1-heat pump cold side inlet;

[0063] Kec0-heat pump cold side outlet. DETAILED DESCRIPTION

[0064] The present invention is described in detail below through specific implementation modes, and the characteristics and advantages of the present invention will become clearer and more specific with these descriptions.

[0065] The present invention provides a nuclear industry wastewater deuterium and tritium removal system, which comprises a membrane evaporation unit 1, a membrane condensation unit 2, a gas circulation unit 3, and a cold and hot water energy conversion unit 4.

[0066] The membrane evaporation unit 1 includes a membrane evaporation module MD, a hot water pump BLh, and a hot water tank TLh.

[0067] The membrane evaporation assembly MD is a single or multiple rolled membrane elements, and the multiple membrane elements are connected in parallel and / or in series. In the membrane evaporation assembly MD, the rolled membrane element is preferably a four-channel rolled membrane element, such as the four-channel rolled membrane element in the Chinese patent CN219518403U. The membrane material is a hydrophobic membrane such as polytetrafluoroethylene PTFE, polyvinylidene fluoride PVDF, polypropylene PP, etc., preferably PP. The average pore size of the membrane is 0.01-1μm, preferably 0.02-0.2μm, more preferably 0.05-0.1μm, and the membrane porosity is 50-90%, preferably 55-85%, and more preferably 60%-80%.

[0068] The film evaporation module MD comprises a film evaporation module hot side inlet Kdh1, a film evaporation module hot side outlet Kdh0, a film evaporation module cold side inlet Kdc1, and a film evaporation module cold side outlet Kdc0.

[0069] The membrane condensation unit 2 includes a cold water tank TLc, a cold water pump BLc, and a membrane condensation component MC.

[0070] The cold water tank TLc is provided with a cold water outlet, a cold water return port, a produced water outlet, a gas outlet and a gas return port. The cold water outlet and the cold water return port are arranged below the liquid level in the cold water tank TLc, the produced water outlet is arranged at the bottom, and the gas outlet and the gas return port are arranged above the liquid level in the cold water tank TLc.

[0071] The membrane condensation module MC is a single membrane element or multiple membrane elements, and the multiple membrane elements are connected in parallel and / or in series. In the membrane condensation module MC, the membrane element is a plate-type, hollow or rolled membrane element, preferably a hollow membrane element. The membrane material is a hydrophobic membrane such as polytetrafluoroethylene PTFE, polyvinylidene fluoride PVDF, polypropylene PP, etc., preferably PP. The average pore size of the membrane is 0.1-0.5μm, preferably 0.1-0.3μm, more preferably 0.2μm, and the membrane porosity is 70-90%, preferably 75-85%, more preferably 80%.

[0072] The membrane condensation module MC comprises a membrane condensation module hot side inlet Kch1, a membrane condensation module hot side outlet Kch0, a membrane condensation module cold side inlet Kcc1, and a membrane condensation module cold side outlet Kcc0.

[0073] The gas circulation unit 3 includes a gas storage tank TG, a vacuum pump Bg, and a gas exhaust valve VG.

[0074] The hot and cold water energy conversion unit 4 includes a heat pump ER. The heat pump ER is provided with a heat pump hot side inlet Keh1, a heat pump hot side outlet Keh0, a heat pump cold side inlet Kec1, and a heat pump cold side outlet Kec0. The heat pump ER is a water source heat source. Through the heat pump principle, the cold side inlet and outlet water sources can be converted to the hot side inlet and outlet water sources, so that the hot side heat increases and the cold side heat decreases and the temperature decreases. For example, the heat pump model ACW010M-WS of Shandong Entelai Air Conditioning Equipment Co., Ltd.

[0075] The hot water tank TLh is connected to the hot side inlet Kdh1 of the membrane evaporation assembly through the hot water pump BLh, the hot side outlet Kdh0 of the membrane evaporation assembly is connected to the hot side inlet Keh1 of the heat pump, and the hot side outlet Keh0 of the heat pump is connected to the water inlet of the hot water tank TLh.

[0076] The outlet of the gas storage tank TG is connected to the cold side inlet Kdc1 of the membrane evaporation component through the gas discharge valve VG, the cold side outlet Kdc0 of the membrane evaporation component is connected to the hot side inlet Kch1 of the membrane condensation component, and the hot side outlet Kch0 of the membrane condensation component is connected to the gas reflux port of the cold water tank TLc.

[0077] The cold water outlet of the cold water tank TLc is connected to the cold side inlet Kec1 of the heat pump through the cold water pump BLc, the cold side outlet Kec0 of the heat pump is connected to the cold side inlet Kcc1 of the membrane condensation component, and the cold side outlet Kcc0 of the membrane condensation component is connected to the cold water reflux port of the cold water tank TLc.

[0078] The gas outlet of the cold water tank TLc is also connected to the gas storage tank TG through a vacuum pump Bg.

[0079] The vacuum pump Bg is an oil-free vacuum pump, such as a water ring vacuum pump or a diaphragm rotary vane vacuum pump, for example, the Tianjin Jinteng diaphragm vacuum pump model is GM-0.33A.

[0080] In the present invention, the thermal nuclear industrial wastewater to be treated is injected into the hot water tank TLh. During treatment, the hot water pump BLh is started to pump the nuclear industrial wastewater into the hot side inlet Kdh1 of the membrane evaporation component.

[0081] The nuclear industrial wastewater contains water with two or more hydrogen isotopes.

[0082] At the same time, the vacuum pump Bg is started to suck the air in the cold water tank TLc and inject it into the gas storage tank TG, forming a negative pressure in the cold water tank TLc. The gas discharge valve VG at the outlet of the gas storage tank TG is opened to allow the gas to enter the cold side inlet Kdc1 of the membrane evaporation module.

[0083] At this time, on both sides of the membrane of the membrane evaporation component MD are thermal nuclear industrial wastewater and dry cold air. The heat of the thermal nuclear industrial wastewater and light water molecules are exchanged with the dry cold air through the membrane. Under the same vacuum conditions, the light water molecules have a lower boiling point and a higher saturated vapor pressure than the heavy water molecules. When liquid water of different isotopes contacts the membrane, under the pressure difference on both sides of the membrane, water will enter a large number of micropores of the membrane, forming a capillary phenomenon. When evaporation is achieved, the light component is easier to volatilize into steam than the heavy component, and the light and heavy water separation rate is greater than that of the traditional distillation process. After the exchange, the dry cold air is converted into moist hot air, and the membrane evaporation component cold side outlet Kdc0 is taken out and enters the membrane condensation component hot side inlet Kch1; after the exchange, the thermal nuclear industrial wastewater is taken out from the membrane evaporation component hot side outlet Kdh0 and enters the heat pump hot side inlet Keh1, and returns to the hot water tank TLh under the drive of the heat pump ER.

[0084] When the vacuum pump Bg is started, the cold water pump BLc is started to pump the cold water in the cold water tank TLc to the cold side inlet Kec1 of the heat pump, and then enter the cold side inlet Kcc1 of the membrane condensation module from the cold side outlet Kec0 of the heat pump. In the membrane condensation module MC, the two sides of the membrane are the humid hot air and cold water coming out of the cold side outlet Kdc0 of the membrane evaporation module. After the heat and moisture exchange, the humid hot air reduces the temperature, and is connected to the gas reflux port of the cold water tank TLc through the hot side outlet Kch0 of the membrane condensation module, and refluxes to the cold water tank TLc. The cold water returns to the cold water tank TLc through the cold side outlet Kcc0 of the membrane condensation module and the cold water reflux port.

[0085] In this way, the light water in the thermonuclear industrial wastewater is transferred to the cold water tank TLc, and the deuterium and / or tritium content in the thermonuclear industrial wastewater in the hot water tank TLh gradually increases, thereby achieving enrichment.

[0086] The present invention also provides a membrane treatment method for removing deuterium and tritium from nuclear industrial wastewater, and the method is carried out using the nuclear industrial wastewater deuterium and tritium removal system.

[0087] The method separates water containing heavy hydrogen isotopes or water containing heavy oxygen isotopes from nuclear industrial wastewater, wherein the nuclear industrial wastewater contains water containing two or more hydrogen isotopes or contains 18 O isotope of water.

[0088] The thermonuclear industrial wastewater to be treated is injected into the hot water tank TLh of the nuclear industrial wastewater deuterium and tritium removal system. During treatment, the hot water pump BLh is started to pump the nuclear industrial wastewater into the hot side inlet Kdh1 of the membrane evaporation component.

[0089] At the same time, start the vacuum pump Bg to suck the air in the cold water tank TLc and inject it into the gas storage tank TG, forming a negative pressure in the cold water tank TLc. The gas discharge valve VG at the outlet of the gas storage tank TG opens, allowing the gas to enter the cold side inlet Kdc1 of the membrane evaporation module.

[0090] At this time, there are thermonuclear industrial wastewater and dry cold air on both sides of the membrane of the membrane evaporation module MD, and the heat and light water molecules of the thermonuclear industrial wastewater are exchanged with the dry cold air through the membrane.

[0091] In the hot water tank TLh, the temperature of the thermonuclear industrial wastewater is 30-90°C, preferably 70-85°C, such as 75°C.

[0092] In the membrane evaporation module MD, the temperature of the thermal nuclear industrial wastewater side is 30-90° C., preferably 50-65° C., such as 60° C. In the membrane evaporation module MD, the membrane surface flow velocity is 1-5 m / s, preferably 1-3 m / s.

[0093] The temperature of the cold water in the cold water tank TLc is 0-30°C, preferably 5-25°C, more preferably 10-20°C, such as 15°C.

[0094] In the membrane condensation module MC, the temperature of the cold water side is 5-30° C., preferably 8-25° C., more preferably 10-20° C., such as 15° C. In the membrane condensation module MC, the flow velocity on the membrane surface is 1-5 m / s, preferably 1.5-4 m / s.

[0095] The greater the temperature difference on both sides of the membrane, the greater the driving force for mass transfer through the membrane, and the higher the membrane flux; the increase in flow rate on both sides of the membrane causes the fluid to flow turbulently on the membrane surface, making the heat uniform, avoiding temperature polarization and also beneficial to increasing the evaporation and condensation efficiency.

[0096] The flow rate of the vacuum pump Bg is 3-10m / s, preferably 6m / s; the switch of the vacuum pump Bg is started and stopped in association with the pressure of the cold water tank TLc, and the pressure of the cold water tank TLc is controlled to be -98~20kPa, preferably -90~-5kPa; the gas solenoid valve is started and stopped in association with the pressure of the gas storage tank TG, and the pressure range of the gas storage tank TG is controlled to be -100~100kPa, preferably -50~50kPa. The flow rate of the vacuum pump is the flow rate of the gas storage tank TG entering the membrane surface of the membrane element, thereby controlling the ratio of the intake gas volume to the membrane cross-sectional area. If the flow rate is too large, it may cause the pressure difference in and out of the membrane to be too large, causing the membrane back pressure to be damaged. If the flow rate is too small, the effect of purging the water vapor produced on the back side of the membrane may be poor, resulting in too low water production flux. The pressure setting of the cold water tank TLc is based on the same principle. If the maximum pressure value is set too large, it will cause membrane back pressure and damage the membrane. If it is too small, it will cause frequent purging of the membrane surface, causing the vacuum degree to decrease. Only within the above appropriate range can a more efficient detritiation efficiency be obtained.

[0097] Preferably, when the nuclear industrial wastewater deuterium and tritium removal system is started, the membrane channels in the membrane evaporation module MD and the membrane condensation module MC are first wetted with a small flow rate, the flow rate increases from small to large, the initial membrane surface flow rate does not exceed 0.5m / s, preferably 0.1-0.5m / s, the operation time is not shorter than 30min, preferably 10-30min, and then the set flow rate range is reached.

[0098] The method of the present invention can be carried out by using water containing protium and deuterium ( 1 H 2 HO), protium-tritium water ( 1 H 3 HO), deuterium tritium water ( 2 H 3 HO), protium water ( 1 H2O), deuterated water ( 2 H2O), tritium water ( 3 H2O) and water containing 1 H 2 H 18 O. 1 H 3 H 18 O. 2 H 3 H 18 O. 1 H2 18 O. 2 H2 18 O. 3 H2 18 O is used as the influent water, that is, water containing two or more hydrogen isotopes or water containing heavy oxygen isotopes is used as the influent water, so as to achieve the separation of hydrogen isotope water and oxygen isotope water with smaller molecular weight from heavy hydrogen isotope water and oxygen isotope water.

[0099] Example

[0100] Example 1

[0101] The detritiation experiment influent water is injected into the hot water tank TLh of the nuclear industrial wastewater detritium removal system as nuclear industrial wastewater, and the hot water pump BLh is started to pump the nuclear industrial wastewater to the hot side inlet Kdh1 of the membrane evaporation component. The detritiation experiment influent water temperature is 65±2℃.

[0102] At the same time, start the vacuum pump Bg to suck the air in the cold water tank TLc, the temperature is 8±2℃, and inject it into the gas tank TG, forming a negative pressure in the cold water tank TLc, and the gas discharge valve VG at the outlet of the gas tank TG is opened, so that the gas enters the cold side inlet Kdc1 of the membrane evaporation module. The pressure range of the gas tank TG is -30kPa.

[0103] The membrane evaporation module MD adopts a single rolled membrane element, the membrane material is a hydrophobic PTFE membrane material, the average pore size of the membrane is 0.1μm, and the membrane porosity is 60%; it is rolled into four channels (the specific structure is as follows Figure 2 The size is 1812, and the membrane area is 0.3m 2 .

[0104] The membrane condensation module MC adopts a hollow fiber membrane hydrophobic membrane module with a size of 1812 and a membrane area of ​​0.2m 2 The membrane wire diameter is 0.6mm, the average membrane pore size is 0.2μm, and the membrane porosity is 80%. The TLc pressure of the cold water tank is -7kPa, and the cold water temperature is 8±2℃.

[0105] The flow rate of nuclear industrial wastewater injection and cold water inlet is 100L / h, which is equivalent to a membrane surface velocity of 3m / s.

[0106] The influent water for the detritiation experiment was tap water from Jiukeshu area in Tongzhou District, Beijing, with a water conductivity of 140 mg / L and a pH of 7.2. After being treated with a reverse osmosis membrane, the purified water produced had a water conductivity of 80 mg / L and a pH of 7.0. As the influent water quality for the detritiation treatment of this project (simulating the water to be treated), the detritiated water was continuously produced after multiple cycles through the detritiation system, and tritium was concentrated in the concentrated water.

[0107] The equipment ran for 2 hours and produced 3.2L of water. As a comparison sample, pure water was passed through a traditional distillation device to prepare distilled water, which was sampled and analyzed. The specific water quality is shown below.

[0108] Table 1 Detritiation experiment inlet and outlet water quality

[0109]

[0110] The water quality analysis table shows that the primary removal rate of tritium water in the detritium removal device is Rs = 1-0.07 / 0.57 = 87.7%; while the primary removal rate of the traditional distillation device as a comparison item is Rc = 1-0.50 / 0.57 = 12.3%. The membrane water flux is calculated based on the membrane area, and the membrane evaporation flux is Jd = 3.2 / 0.2 / 2 = 8 (L / m 2 h); membrane condensation flux is Jd = 3.2 / 0.3 / 2 = 5.5 (L / m 2 h).

[0111] Example 2

[0112] The device of Example 1 was adopted, and only the pressure setting value of the cold water tank TLc was changed to -45~-65kPa, and the membrane gas flow rate was 8m / s; the pressure setting value of the gas storage tank TG was 25~50kPa, and the other parameters remained unchanged. The equipment was operated for 2 hours, and the water output was 2.2L. The specific water quality was obtained as shown below.

[0113] Table 2 Detritiation experiment inlet and outlet water quality

[0114]

[0115] The water quality analysis table shows that the primary removal rate of tritium water in the detritium removal device is Rs = 1-0.06 / 0.57 = 89.5%; the membrane evaporation flux is Jd = 2.2 / 0.2 / 2 = 5.5 (L / m 2 h); membrane condensation flux is Jd = 2.2 / 0.3 / 2 = 3.5 (L / m 2 h). Although the membrane flux is lower than that of the previous embodiment, the primary tritium removal rate is increased.

[0116] The present invention is described in detail above in conjunction with specific embodiments and / or exemplary examples and drawings, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A membrane method for removing deuterium and tritium from nuclear industrial wastewater, characterized in that: The method is carried out by using a nuclear industrial wastewater deuterium and tritium removal system, and the method separates water containing heavy hydrogen isotopes or water containing heavy oxygen isotopes from nuclear industrial wastewater, wherein the nuclear industrial wastewater contains water containing two or more hydrogen isotopes or contains 18 O isotope of water, The nuclear industry wastewater deuterium and tritium removal system comprises a membrane evaporation unit (1) and a membrane condensation unit (2). The membrane evaporation unit (1) comprises a membrane evaporation module (MD), a hot water pump (BLh), and a hot water tank (TLh). The membrane condensation unit (2) comprises a cold water tank (TLc), a cold water pump (BLc), and a membrane condensation module (MC). The thermonuclear industrial wastewater to be treated is injected into the hot water tank (TLh) of the nuclear industrial wastewater deuterium and tritium removal system. During treatment, the hot water pump (BLh) is started to pump the nuclear industrial wastewater into the hot side inlet (Kdh1) of the membrane evaporation component. At the same time, the vacuum pump (Bg) is started to suck the air in the cold water tank (TLc) and inject it into the gas storage tank (TG). A negative pressure is formed in the cold water tank (TLc). The gas discharge valve (VG) at the outlet of the gas storage tank (TG) is opened to allow the gas to enter the cold side inlet (Kdc1) of the membrane evaporation module. At this time, on both sides of the membrane of the membrane evaporation module (MD) are the thermonuclear industrial wastewater and dry cold air. The heat and light water molecules of the thermonuclear industrial wastewater are exchanged to the dry cold air through the membrane. In the membrane condensation module (MC), the temperature of the cold water side is 0-30°C, and the flow rate on the membrane surface is 1-5m / s.

2. The method according to claim 1, characterized in that In the membrane evaporation module (MD), the temperature of the hot wastewater side is 30-90° C., and the flow rate on the membrane surface is 1-5 m / s.

3. The method according to claim 1, characterized in that The membrane evaporation module (MD) is a single or multiple rolled membrane elements. The membrane evaporation assembly (MD) is provided with a membrane evaporation assembly hot side inlet (Kdh1), a membrane evaporation assembly hot side outlet (Kdh0), a membrane evaporation assembly cold side inlet (Kdc1), and a membrane evaporation assembly cold side outlet (Kdc0). The membrane condensation module (MC) is a single or multiple hollow membrane elements. The membrane condensation module (MC) is provided with a membrane condensation module hot side inlet (Kch1), a membrane condensation module hot side outlet (Kch0), a membrane condensation module cold side inlet (Kcc1), and a membrane condensation module cold side outlet (Kcc0).

4. The method according to claim 1, characterized in that: When the nuclear industrial wastewater deuterium and tritium removal system is started, the initial membrane surface flow rate does not exceed 0.5 m / s, and the operating time is not shorter than 30 minutes.

5. The method according to claim 1, characterized in that The method uses hydrogen-deuterium water, hydrogen-deuterium water, deuterium-deuterium water, hydrogen-deuterium water, deuterium-deuterium water and tritium water as influent water to separate hydrogen isotope water with a smaller molecular weight from heavy hydrogen isotope water. Or with 18 O water is used as the influent water to separate the oxygen isotope water with smaller molecular weight from the heavy oxygen isotope water.

6. A system for removing deuterium and tritium from nuclear industrial wastewater, characterized in that: The nuclear industry wastewater detritiation system comprises a membrane evaporation unit (1), a membrane condensation unit (2), a gas circulation unit (3), and a cold and hot water energy conversion unit (4). The membrane evaporation unit (1) comprises a membrane evaporation module (MD), a hot water pump (BLh), and a hot water tank (TLh). The membrane condensation unit (2) comprises a cold water tank (TLc), a cold water pump (BLc), and a membrane condensation module (MC). The membrane evaporation module (MD) is a single or multiple rolled membrane elements. The membrane evaporation assembly (MD) comprises a membrane evaporation assembly hot side inlet (Kdh1), a membrane evaporation assembly hot side outlet (Kdh0), a membrane evaporation assembly cold side inlet (Kdc1), and a membrane evaporation assembly cold side outlet (Kdc0). The membrane condensation module (MC) is a single multiple hollow membrane element. The membrane condensation component (MC) comprises a membrane condensation component hot side inlet (Kch1), a membrane condensation component hot side outlet (Kch0), a membrane condensation component cold side inlet (Kcc1), and a membrane condensation component cold side outlet (Kcc0).

7. The nuclear industry wastewater deuterium and tritium removal system according to claim 6, characterized in that: The gas circulation unit (3) comprises a gas storage tank (TG), a vacuum pump (Bg), and a gas discharge valve (VG). The hot and cold water energy conversion unit (4) comprises a heat pump (ER), and the heat pump (ER) is provided with a heat pump hot side inlet (Keh1), a heat pump hot side outlet (Keh0), a heat pump cold side inlet (Kec1), and a heat pump cold side outlet (Kec0).

8. The nuclear industry wastewater deuterium and tritium removal system according to claim 7, characterized in that: The hot water tank (TLh) is connected to the hot water pump (BLh) and the hot side inlet (Kdh1) of the membrane evaporation component in sequence, the hot side outlet (Kdh0) of the membrane evaporation component is connected to the hot side inlet (Keh1) of the heat pump, and the hot side outlet (Keh0) of the heat pump is connected to the water inlet of the hot water tank (TLh); The outlet of the gas storage tank (TG) is connected to the cold side inlet (Kdc1) of the membrane evaporation component through the gas discharge valve (VG), the cold side outlet (Kdc0) of the membrane evaporation component is connected to the hot side inlet (Kch1) of the membrane condensation component, and the hot side outlet (Kch0) of the membrane condensation component is connected to the gas reflux port of the cold water tank (TLc).

9. The nuclear industry wastewater deuterium and tritium removal system according to claim 7, characterized in that: The cold water outlet of the cold water tank (TLc) is connected to the cold side inlet (Kec1) of the heat pump through the cold water pump (BLc), the cold side outlet (Kec0) of the heat pump is connected to the cold side inlet (Kcc1) of the membrane condensation module, and the cold side outlet (Kcc0) of the membrane condensation module is connected to the cold water return port of the cold water tank (TLc). The gas outlet of the cold water tank (TLc) is also connected to the gas storage tank (TG) through a vacuum pump (Bg).

Images