Nanocomposite desalination unit

Abstract

FIELD: desalination equipment.SUBSTANCE: invention relates to devices for desalination of sea water, purification of industrial or domestic waste water by means of evaporation and subsequent condensation. A nanocomposite desalination unit comprising a heater; a brine tank; a plurality of MWCNT-carbon composite evaporator elements, which are narrow, vapor-permeable, hydrophobic cups partially immersed in the brine tank and communicating through internal cavities with a steam inlet manifold; a steam transfer pump; a steam outlet manifold communicating with a plurality of MWCNT-fluoroplastic composite condenser elements, which are narrow, vapor-impermeable, hydrophobic tubes; a condensate tank; and a refrigerator.EFFECT: increase in energy efficiency, specific productivity, and quality of condensate purification.3 cl, 4 dwg

Description

[0001] The invention relates to devices for desalination of sea water, purification of industrial or domestic waste water by means of evaporation and subsequent condensation.

[0002] The development of modern composite materials is expanding the boundaries of their use. For example, superhydrophobic composites containing Dealtom brand multi-walled carbon nanotubes (MWCNTs) have been produced in the carbon nanomaterials laboratories of the Autonomous Non-Profit Organization of Higher Education "Russian New University" (ANO VO "RosNOU") [1] and the Scientific and Production Enterprise "Center for Nanotechnology" [2].

[0003] A study of the properties of the MWCNT-carbon composite revealed high porosity (over 75%) and superhydrophobicity (with a water droplet contact angle over 150°), making this material suitable for the production of vapor-permeable, water-repellent membranes. Furthermore, this composite exhibits high chemical resistance, heat resistance (up to 300°C in air and up to 2000°C in inert gas), a high light absorption coefficient, and high thermal conductivity.

[0004] MWCNT-fluoroplastic composite, in contrast, has low porosity (vapor impermeability) but higher hydrophobicity: the water droplet contact angle is greater than 156°, and the droplet roll-off angle is less than 12°. This composite also exhibits high chemical and heat resistance (up to 300°C in air), as well as high thermal conductivity.

[0005] Superhydrophobic nanocomposites are applicable for the manufacture of evaporator and condenser elements of desalinators, distillers, distillation cubes and other similar devices, as well as for the production, separation and utilization of steam in steam generators, steam engines and turbines.

[0006] The "Solar Water Distillation Station" [3] is well-known. Its technical efficiency is achieved by boiling and condensing water at low pressure and temperature using reflective concentric mirrors and a vacuum pump. The disadvantages of this device include the low quality of the purified water, as the vigorous boiling process promotes the formation of difficult-to-separate aerosols of ultra- and nano-dispersed particles entrained in the condensate by steam flows.

[0007] Another well-known "Salt Water Desalination Device" [4] is essentially a piston-type pressure distillation unit, operating alternately in vacuum boiling and pressure condensation modes. The technical result of achieving high productivity is achieved primarily due to the short cycle time. Disadvantages of this device include the conditions for the formation of aerosols of polluting particles during boiling, a relatively small condensation area in the tubular heat exchanger, and low heat transfer efficiency in fast processes.

[0008] "Boron-doped carbon foam evaporator for seawater desalination and its manufacturing method" [5] is known. This device uses a nanocomposite of boron-modified carbon allotropes, which has high photothermal properties due to the content of carbon nanotubes and exhibits hydrophilic properties due to the modification.

[0009] Its operating principle is based on a low-density nanocomposite foam floating in seawater, acting as a photothermal layer a few centimeters above the water surface, converting solar radiation into heat. The capillary effect in the porous hydrophilic material ensures a continuous supply of water from the reservoir to the heated photothermal layer, resulting in vaporization over a large specific surface area of ​​its internal surface. The disadvantages of this evaporator include its poor performance characteristics and the unsolved problem of removing salt deposits formed during the evaporation of seawater within the porous photothermal layer.

[0010] The prototype of the invention is a desalination plant [6], comprising a heat-insulated chamber equipped with pipes for the supply and discharge of desalinated water, a heating element, and a condenser. The heat-insulated chamber is hermetically sealed to form a closed air circuit, and an electric fan is located within its cavity with the ability to supply air to the first film apparatus, in front of the inlet of which is located the outlet of the pipe for supplying desalinated water, the drain of which is located above the brine receiver.

[0011] Further along the closed air circuit is the first louvered separator, the outlet of which communicates with the inlet of the second film separator, the drain of which is located above the fresh water receiver. The inlet of the second film separator is designed to accept cooled fresh water. A second louvered separator is mounted above the inlet of the second film separator.

[0012] The air heater's heating element is installed between the second louvered separator and the electric fan. The outlet of the fresh water receiver, through the first pump and the cooler, is connected to the fresh water line, one branch of which is connected to the inlet of the second film separator, and the other to the fresh water consumers.

[0013] The prototype's goal of increasing productivity is achieved primarily by increasing the evaporation area created by the thin liquid film of the first film apparatus and increasing the condensation area on the thin liquid film of the second film apparatus, which facilitates intensive heat and mass transfer between the air and the liquid films. The prototype's drawbacks include the large number of heat transfer mediators, which significantly reduce their intensity and efficiency: air and water coolants, heat exchangers, heaters, fans, and pumps, as well as the low efficiency of louvered steam separators.

[0014] The tasks of increasing energy efficiency, specific productivity, condensate purification quality and improving operational properties are solved in a nanocomposite desalination plant consisting of a heater; a brine tank; a plurality of MWCNT-carbon composite evaporator elements communicating with a steam inlet manifold; a vapor transfer pump; a steam outlet manifold communicating with a plurality of MWCNT-fluoroplastic composite condenser elements; a condensate tank; and a refrigerator.

[0015] The basic diagram of the nanocomposite desalination plant is shown in Fig. 1. The device according to Fig. 1 consists of a heater (not shown in Fig. 1); a brine tank 1; a plurality of MWCNT-carbon composite evaporator elements 2, which are narrow vapor-permeable hydrophobic cups partially immersed in the brine tank 1 and communicating through internal cavities with a steam inlet manifold 3; a vapor pump 4; a steam outlet manifold 5, communicating with a plurality of MWCNT-fluoroplastic composite condenser elements 6, which are narrow vapor-impermeable hydrophobic tubes; a condensate tank 7; a refrigerator (not shown in Fig. 1).

[0016] The system shown in Fig. 1 operates as follows. Heat flow Q, necessary to maintain evaporation, is supplied to brine tank 1 from the heater. Evaporation (without boiling) occurs both from the liquid surface and from the entire combined surface of the multiple MWCNT-carbon composite evaporation elements 2.

[0017] The structure of the MWCNT-carbon composite evaporator element 2 with an explanation of its operating principles is shown in Fig. 2. Water vapor generated in the internal cavities of each MWCNT-carbon composite evaporator element 2 is collected by a vapor inlet collector 3 located above the liquid surface and is fed to the inlet of a vapor pump 4, which pumps the vapor into a vapor outlet collector 5. The vapor outlet collector 5 distributes water vapor among a plurality of MWCNT-fluoroplastic composite condenser elements 6, on the walls of which vapor condensation occurs.

[0018] The structure of the MWCNT-fluoroplastic composite capacitor element 6 with an explanation of its operating principles is shown in Fig. 3. Heat Q generated during steam condensation is removed through the heat-conducting walls of the MWCNT-fluoroplastic composite capacitor element 6 to the refrigerator, and the resulting condensate is removed under the action of gravity to the condensate tank 7.

[0019] The technical result of increasing the specific productivity of the device is due to evaporation from the large total surface area of ​​multiple MWCNT-carbon composite evaporator elements 2. The high thermal conductivity of their MWCNT-carbon composite walls ensures efficient heat exchange, necessary for intensive vaporization. Furthermore, oil and fat films may form on the brine surface, impeding evaporation. These films are absent within the volume of liquid in contact with the hydrophobic, vapor-permeable surface of the MWCNT-carbon composite evaporator elements 2.

[0020] Another reason for the increased specific performance of the device is the large specific surface area and efficiency of the MWCNT-fluoroplastic composite capacitor element 6. Due to its high thermal conductivity, the walls of the element intensively remove heat Q generated during condensation. Adhesive forces arising from the molecular interactions between water and the solid surface are observed even in superhydrophobic substances.

[0021] Thus, the surface of the MWCNT-fluoroplastic composite capacitor element 6 serves as a condensation center for water vapor. As the condensate droplet grows, gravity eventually overcomes the adhesive force, causing it to roll down, dragging smaller droplets along the way and freeing the surface for new droplets to condense. The superhydrophobic surface prevents the formation of a water film that would impede further condensation.

[0022] The technical result of improving the quality of condensate purification is due to evaporation in the absence of boiling, which eliminates the formation of difficult-to-separate aerosols from ultra- and nano-dispersed particles carried away by steam flows into the condensate.

[0023] The technical result of improving the device's performance is due to the high chemical and thermal stability of the nanocomposites—they are not subject to corrosion. Furthermore, during long-term operation, the MWCNT-carbon composite evaporator elements 2 and MWCNT-fluoroplastic composite condenser elements 6 gradually become contaminated, degrading their performance, and require periodic maintenance and cleaning. Depending on the nature of the contamination, they can be washed with strong substances and solvents and / or subjected to heat treatment at high temperatures.

[0024] In one particular case, the device according to Fig. 1 is distinguished in that solar radiation serves as a heater, the walls of the brine container 1 are made of a material transparent to infrared and visible light, the convection type steam pump 4 does not contain moving mechanical parts and is a pipeline connecting the steam inlet manifold 3 with the steam outlet manifold 5, and the refrigerator is the flow of atmospheric air.

[0025] The device shown in Fig. 1 operates as follows. Sunlight passing through the transparent walls of brine tank 1 is effectively absorbed by MWCNT-carbon composite evaporator elements 2, providing heat Q necessary for intensive evaporation. The steam generated within the plurality of MWCNT-carbon composite evaporator elements 2 is collected by steam inlet manifold 3 and fed through a pipeline to steam outlet manifold 5, where it is distributed among the plurality of MWCNT-fluoroplastic composite condenser elements 6, cooled by atmospheric air flows. The pressure drop required for convective pumping of vapors is created by the temperature difference between the solar-heated MWCNT-carbon composite evaporative elements 2 and the atmospheric-air-cooled MWCNT-fluoroplastic composite condenser elements 6. The vapor condensed on the walls of the MWCNT-fluoroplastic composite condenser elements 6 flows down in the form of drops into the condensate tank 7.

[0026] The technical result in this particular case is distinguished by the fact that increased energy efficiency is achieved through the use of natural energy sources—solar and wind—without additional energy consumption or mechanical losses. Furthermore, increased specific productivity is achieved due to the high ability of the MWCNT-carbon composite to absorb solar radiation, converting it into heat.

[0027] Another particular case is shown in Fig. 4. The device according to Fig. 4 is distinguished in that the MWCNT-fluoroplastic composite condenser elements 6 pass through the brine tank 1, alternating with the MWCNT-carbon composite evaporator elements 2; converging-diffuser nozzles 8 are connected to the lower ends of the MWCNT-fluoroplastic composite condenser elements 6; the brine tank 1 contains a water inlet 9 and a water overflow 10.

[0028] The operation of the device shown in Fig. 4 is characterized by the following. The vapor pump 4 creates a high excess pressure in the vapor outlet manifold 5, which creates conditions for the condensation of vapor in the MWCNT-fluoroplastic composite condenser elements 6 at a temperature higher than the temperature at which evaporation occurs in the MWCNT-carbon composite evaporator elements 2.

[0029] The heat flux Q generated during condensation, due to the temperature gradient, passes through the heat-conducting nanocomposite walls and a small layer of liquid from the hotter inner surface of the MWCNT-fluoroplastic composite condenser elements 6 to the cooler inner surface of the MWCNT-carbon composite evaporator elements 2. The formed condensate flows in droplets along the hydrophobic inner surface of the MWCNT-fluoroplastic composite condenser element 6 to the confuser-diffuser nozzle 8, in the confuser of which it mixes with the remains of uncondensed vapor, and in the diffuser of which the vapor-droplet mixture undergoes adiabatic expansion and cooling. The cooled vapor condenses on the surface of the droplets and is collected in the condensate tank 7.

[0030] Continuous replenishment of brine tank 1 with running water through water inlet 9 and water overflow 10 regulates the permissible salt concentration and liquid level in it.

[0031] The technical result in this particular case is distinguished by the fact that the increase in energy efficiency is due to the recovery of the work performed by the vapor pump 4 for compressing the working gas, and the recovery of the heat of evaporation-condensation; the result of the increase in the specific productivity of the device is due to the high intensity of heat exchange processes, as a consequence of the high temperature gradient between the MWCNT-fluoroplastic composite condenser elements 6 and the MWCNT-carbon composite evaporator elements 2; the result of the improvement in the operational properties of the device is due to the stabilization of the salt concentration in the brine tank 1, which allows the operation of the device in a continuous mode.

[0032] LITERATURE

[0033] 1. Laboratory of Carbon Nanomaterials / / ANO VO "Russian New University" / / https: / / rosnou.ru / nauka / labs /

[0034] 2. Scientific and Production Enterprise "Center for Nanotechnology" / / http: / / dealtom.ru

[0035] 3. Almohammed Omar Abdulhadi Mustafa, Timerbaev Nail Farilovich, Shakurova Rozalina Zufarovna. Solar station for water distillation / / Federal State Budgetary Educational Institution of Higher Education "Kazan State Power Engineering University" / / Patent RU 2767322 C1 / 2021 / IPC C02F 1 / 14 / https: / / patents.s3.yandex.net / RU2767322C1 20220317.pdf

[0036] 4. Ryavkin Gleb Nikolaevich, Solomin Evgeniy Viktorovich, Osintsev Konstantin Vladimirovich and others. Device for desalination of salt water / / Federal State Autonomous Educational Institution of Higher Education "Southern State University (National Research University)" / Patent RU 2801386 C1 / 2023 / IPC C02F 1 / 04, B01D 1 / 28, B01D 3 / 42 / https: / / yandex.ru / patents / doc / RU2801386C1 20230808

[0037] 5. Zhang Qiao, Huo Yunying, Wang Ying, Peng Feng. Boron-doped carbon foam evaporator for seawater desalination and its manufacturing method / / Guangzhou University / / Patent CN 118458869 A / 2024 / IPC C02F 1 / 04, C02F 1 / 14 / https: / / patentimages.storage.googleapis.com / 85 / 62 / 22 / f459d6043cfbaa / CN118458869A.pdf

[0038] 6. Statsenko Vladimir Nikolaevich. Desalination plant / / Far Eastern Federal University / / Patent RU 2677153 C1 / 2018 / IPC C02F 1 / 04, B01D 1 / 28, B01D 3 / 42 / https: / / patents.s3.yandex.net / RU2677153C1 20190115.pdf

Claims

1. A nanocomposite desalination unit comprising a heater; a brine tank; a plurality of MWCNT-carbon composite evaporator elements, which are narrow, vapor-permeable, hydrophobic cups partially immersed in the brine tank and communicating through internal cavities with a steam inlet manifold; a steam transfer pump; a steam outlet manifold communicating with a plurality of MWCNT-fluoroplastic composite condenser elements, which are narrow, vapor-impermeable, hydrophobic tubes; a condensate tank; and a refrigerator.

2. A nanocomposite desalination plant according to claim 1, characterized in that solar radiation serves as a heater, the walls of the brine tank are made of a material that is transparent to infrared and visible light, the convection-type vapor transfer pump does not contain moving mechanical parts and is a pipeline connecting the vapor inlet manifold to the vapor outlet manifold, and the refrigerator is atmospheric air flows.

3. A nanocomposite desalination plant according to claim 1, characterized in that the MWCNT-fluoroplastic composite condenser elements pass through the brine tank, alternating with MWCNT-carbon composite evaporator elements; confuser-diffuser nozzles are attached to the lower ends of the MWCNT-fluoroplastic composite condenser elements; the brine tank contains a water inlet and a water overflow.

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