Interface evaporative crystallization assembly and system for simultaneous evaporation and fractional quality crystallization

Abstract

The application relates to an interface evaporation crystallization assembly and system for synchronously performing evaporation and fractional quality crystallization, and the system comprises a fractional quality crystallization device and a solar heat focusing device. The fractional quality crystallization device comprises an evaporation box and an evaporation crystallization unit embedded in the evaporation box; the solar heat focusing device is partially embedded in the fractional quality crystallization device; a first porous structure is arranged on the evaporation crystallization unit; a second porous structure for performing interface evaporation and fractional quality crystallization on a salt solution is arranged on the first porous structure, and the second porous structure is a controllable nano-porous medium; the evaporation crystallization units are arranged at intervals along the heat radiation direction of the solar heat focusing device, and the inner cavity of the evaporation box is divided into multiple cavities, and the cavities are generation cavities for performing interface evaporation and fractional quality crystallization. Through the combination of the solar heat supply mode and the multi-stage gradient heat transfer, the application can realize efficient coupling of evaporation-crystallization-separation and purification by using solar energy, and a clean and efficient treatment system with the advantages of membrane method and thermal method is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of interfacial evaporative crystallization and solute separation, and in particular to an interfacial evaporative crystallization assembly and system for simultaneously performing evaporation and fractionated crystallization. BACKGROUND

[0002] In the process of water resource treatment and recycling, salt ions in raw water are continuously enriched, and a large amount of high-salt wastewater (salt ion concentration > 1wt%) is inevitably produced; a large amount of high-salt wastewater is produced in the treatment processes such as seawater desalination, boiler circulating water, and shale gas backflow water. The conventional "membrane" treatment technology can realize the separation and purification of salt ions, but cannot cope with the salt crystallization and high osmotic pressure problems of high-salt wastewater. The "thermal" treatment technology can recover water resources through evaporation, but cannot realize the separation and purification of salt. The existing high-salt wastewater treatment process is complex, energy consumption is huge, and the energy and environmental burden is heavy. Therefore, it is urgent to develop a clean and efficient "zero discharge" treatment technology with the advantages of membrane and thermal methods to ensure clean energy utilization and social sustainable development. SUMMARY

[0003] To solve the problem of high-salt wastewater treatment, the present application provides an interfacial evaporative crystallization assembly and system for simultaneously performing evaporation and fractionated crystallization. By setting a porous structure, the salt solution is absorbed and retained in the porous structure. Then, by combining another controllable nanoporous medium with the porous structure, under the premise of fixed solar energy density, the porous structure evaporates and crystallizes relatively quickly.

[0004] The first aspect of the present application provides an interfacial evaporative crystallization assembly for simultaneously performing evaporation and fractionated crystallization, comprising a heat-conducting plate body, a first porous structure, and a second porous structure. The first porous structure is used to attract a salt solution, and the first porous structure is combined with one side of the heat-conducting plate body. The second porous structure is arranged on the side of the first porous structure away from the heat-conducting plate body, and the second porous structure is connected with the first porous structure through the heat-conducting plate body. The second porous structure is a controllable nanoporous medium with molecular sieve selective channels, which is used to make the salt solution attracted by the first porous structure simultaneously perform selective evaporation and directional crystallization of different solutes on its surface. The controllable nanoporous medium is any one or a combination of any multiple of MXenes, molybdenum disulfide, graphene, graphene oxide, hexagonal boron nitride, single-element two-dimensional semiconductor, and two-dimensional van der Waals oxide.

[0005] Currently, scholars mainly focus on the application of interfacial evaporation technology in the field of seawater desalination, and pay little attention to the development potential of interfacial evaporation technology in the field of salt separation and evaporation crystallization. Therefore, the mainstream research work hopes to improve the energy conversion rate of "solar energy-water vapor" by improving the light absorption rate of nano-porous materials, improving the heat management of the system, and improving the molecular transport characteristics. However, the above measures do not effectively touch the fundamental contradiction between the low energy density of solar energy (1 kW / m 2 ) and the high latent heat of water evaporation (~2400 kJ / kg). Even under the premise of 100% utilization of solar energy, the rate of interfacial evaporation crystallization is bound to be severely limited.

[0006] Applicants have found that by precisely controlling the pore size of nanomaterials and the interfacial properties, water molecules can be excited into a high-activity, metastable state, which can greatly reduce the latent heat of phase transition of interfacial evaporation. Under the premise of fixed solar energy density, studying the phase transition behavior of water molecules and reducing the latent heat of interfacial phase transition can break this inherent contradiction.

[0007] Therefore, by using a porous structure to attract and absorb salt solution, and combining it with the above controllable nano-porous medium, the component can utilize the heat absorbed by the first porous structure to complete crystallization quickly on the interface of the controllable nano-porous medium during evaporation, so that the interfacial evaporation crystallization has a high rate.

[0008] Professor Liangti Qu's team at Tsinghua University reported that the steam output of interfacial evaporation can exceed the thermodynamic limit by more than 2 times (100% utilization of solar energy, phase transition latent heat of 2400 kJ / kg corresponding to the evaporation amount defined as the thermodynamic limit): It is speculated that the reason is that the latent heat of phase transition of interfacial evaporation is much lower than the theoretical value. Professor Jun Ma of Harbin Institute of Technology and Yuet al. at the University of Texas observed "active state" water molecules with weak hydrogen bonding in hydrogel and GO composite photothermal materials. The number of hydrogen bonds and the hydrogen bond breaking energy barrier of active state water molecules are much lower than those of free water molecules, which give them much lower phase transition latent heat than the theoretical standard value.

[0009] However, the above research only confirms the existence of "active state" water, but cannot specifically determine the micro-thermodynamic conditions required for the formation of active state water and quantify the evaporation latent heat value, and does not reveal the formation and regulation mechanism of "active state" water. In addition to thermodynamic properties, the formation rate and evaporation rate of active state water determine the contribution of active state water to the actual evaporation process; and currently, there is a lack of attention to the dynamic characteristics of active state water.

[0010] On the other hand, the molecular structure and interface chemical properties of the photothermal evaporation interface can affect the metastable zone width (supersolubility) of the salt solution. According to the classical heterogeneous nucleation model and the diffusion control mechanism, the change in the metastable zone width can cause changes in the nucleation rate and growth rate of salt crystallization. The increase in the metastable zone width can further increase the salt concentration at the interface, thereby affecting the phase change latent heat of evaporation crystallization.

[0011] Therefore, it is necessary to explore the formation mechanism of "active state" water from the thermodynamic point of view, and to explore the phase change rate of "active state" water from the kinetic point of view, and to consider the influence law of the supersolubility of salt ions, and to establish the interface regulation mechanism of the phase change latent heat.

[0012] The second aspect of the present application also provides an interface evaporation crystallization system for simultaneously performing evaporation and fractionation crystallization, comprising a fractionation crystallization device and a solar thermal focusing device. The fractionation crystallization device comprises an evaporation box and an evaporation crystallization unit built in the evaporation box; a part of the solar thermal focusing device is embedded in the fractionation crystallization device to form a heat source in the evaporation box; wherein the evaporation crystallization unit is provided with a first porous structure for attracting salt solution, and the first porous structure is provided with a second porous structure; the second porous structure is a controllable nano-porous medium for enabling the salt solution attracted by the first porous structure to simultaneously perform evaporation and fractionation crystallization on the interface of the second porous structure. The controllable nano-porous medium is any one or any combination of MXenes, molybdenum disulfide, graphene, graphene oxide, hexagonal boron nitride, single-element two-dimensional semiconductor, and two-dimensional van der Waals oxide.

[0013] The interface evaporation crystallization system for simultaneously performing evaporation and fractionation crystallization of the present application utilizes only solar energy and converts it into heat energy, which can heat the system without the need for other forms of energy input, and combines the characteristics of the controllable nano-porous medium having molecular sieve and the Donnan effect, so that the salt solution can be partially separated by the controllable nano-porous medium. The combination of the solar heating method and the multi-stage gradient heat transfer can realize efficient coupling of evaporation-crystallization-separation and purification by using solar energy, thereby achieving a clean and efficient "zero emission" treatment technology that combines the advantages of membrane and thermal methods, and achieving the goal of water production and salt separation and crystallization.

[0014] In short, salt solution evaporation crystallization and separation and purification have always been key problems in this field. The present system can realize simultaneous evaporation and fractionation crystallization by using only solar energy through the interface evaporation multi-stage system. The energy density of solar energy is low, but the phase change latent heat of water evaporation is high. The present system can overcome this problem by using interface regulation and multi-stage recovery.

[0015] The evaporation crystallization units are arranged along the heat radiation direction of the solar heat focusing device, and divide the inner cavity of the evaporation box into a plurality of cavities, which are generation cavities for interfacial evaporation and quality separation crystallization. It should be understood that the generation cavities are sealed from each other.

[0016] The above-mentioned multi-stage gradient heat transfer is that, in the above-mentioned plurality of generation cavities, the vapor after heat transfer exchanges heat with the next stage interface to condense, and then drives the evaporation crystallization of the next stage. That is, the interfacial evaporation crystallization system which synchronously performs evaporation and quality separation crystallization uses solar energy as a heat source, that is, provides an energy source for the interfacial evaporation and crystallization of the salt solution, and through the multi-stage heat transfer arrangement, utilizes the latent heat released by the condensation of the vapor to drive the interfacial evaporation and quality separation crystallization of the next stage, so as to obtain a clean and efficient, high heat energy utilization rate, and has the advantages of both membrane method and thermal method, "zero discharge" treatment technology, which realizes the goal of water production and salt separation crystallization at one time.

[0017] In some embodiments, a part of the first porous structure is arranged in the evaporation box, and the other part extends out of the evaporation box, and the part extending out of the evaporation box is used for guiding the salt solution into the part of the first porous structure arranged in the evaporation box. The first porous structure can be made of nylon material and can be designed as a layer structure or a strip structure. In this way, the salt solution can be attracted into the evaporation box without the driving of other devices.

[0018] In some embodiments, the evaporation crystallization unit further comprises a heat conduction plate body connected to the inner wall of the evaporation box; the first porous structure is connected to the heat conduction plate body, so that the heat conduction plate body is located on the side of the first porous structure close to the heat source; and the second porous structure is arranged on the side of the first porous structure away from the heat source.

[0019] In some embodiments, a recovery groove is arranged in the generation cavity; the feed inlet of the recovery groove corresponds to the plate surface of the heat conduction plate body or the second porous structure facing the generation cavity, and is used for collecting the materials on the plate surface. In this way, the materials (water or crystals) collected from the heat conduction plate body or the second porous structure can be conveniently collected.

[0020] In some embodiments, the solar heat focusing device comprises a heat transfer plate; a part of the heat transfer plate extends into the evaporation box, and the part forms the heat source. Since the solar heat focusing can convert solar energy into heat energy, the above-mentioned heat transfer plate can be made of copper plate. The copper plate transmits heat energy to the evaporation crystallization unit in contact with the copper plate, and the copper plate and the evaporation crystallization unit in contact with the copper plate form a main quality separation crystallization system. After heat transfer, the evaporation interface drives the evaporation of the solution and the crystallization of the salt, and the vapor exchanges heat with the next stage interface to condense and drive the evaporation crystallization of the next stage.

[0021] In some embodiments, the heat transfer plate comprises a horizontally arranged upper roof and a vertically arranged lower plug; the lower side of the upper roof is connected with the upper end of the lower plug; the lower plug extends into the evaporation box, and the upper roof is exposed outside the evaporation box. The upper roof is arranged to ensure sufficient light area.

[0022] In some embodiments, the upper side of the upper roof is provided with a light-absorbing coating. The light-absorbing coating can efficiently convert solar energy into heat energy.

[0023] In some embodiments, the lower plug is located in the middle of the evaporation box; the two side surfaces of the lower plug are respectively provided with the first porous structure. In this way, the lower plug in the middle of the evaporation box is used as a heat source to transfer heat to both sides, thereby ensuring efficient use of heat energy.

[0024] In some embodiments, the interface evaporation crystallization system for simultaneously performing evaporation and fractionated crystallization further comprises a feed liquid tank located at the lower side of the evaporation box, and a part of the first porous structure extends into the feed liquid tank; the feed liquid tank is provided with a heat insulation plate for dividing the feed liquid tank into two chambers; the heat insulation plate is provided with a channel for communicating with one of the two chambers, and the channel is provided with a valve assembly. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and together with the description serve to explain the principles of the present application. In the drawings:

[0026] Figure 1 FIG. 1 is a schematic diagram of an interface evaporation crystallization system for simultaneously performing evaporation and fractionated crystallization according to an embodiment of the present application;

[0027] Figure 2 FIG. 2 is a schematic diagram of a solar heat focusing device according to an embodiment of the present application; Figure 1 FIG. 3 is a partial enlarged view of position A in FIG. 2;

[0028] Figure 3 FIG. 4 is a schematic diagram of a controllable nano-porous medium according to an embodiment of the present application;

[0029] Figure 4 FIG. 5 is a schematic diagram of a working process of the controllable nano-porous medium according to an embodiment of the present application;

[0030] 100-solar heat focusing device, 110-heat transfer plate, 111-upper roof, 112-lower plug, 120-light-absorbing coating, 200-fractionated crystallization device, 210-evaporation crystallization unit, 211-first porous structure, 212-second porous structure, 213-heat conduction plate body, 220-evaporation box, 230-recovery tank, 300-feed liquid tank, 310-heat insulation plate, 311-valve assembly. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with embodiments and drawings. The schematic embodiments of the present application and the descriptions thereof are only used to explain the present application and do not limit the present application.

[0032] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one of ordinary skill in the art that the present application can be practiced without these specific details. In other instances, well-known structures, circuits, materials or processes have not been described in detail in order to avoid obscuring the present application.

[0033] Reference throughout this specification to "one embodiment", "an embodiment", "one example" or "an example" means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present application. Thus, appearances of the phrases "one embodiment", "an embodiment", "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics can be combined in any suitable

[0034] In the description of the present application, it needs to be understood that the terms "front", "back", "left", "right", "top", "bottom", "vertical", "horizontal", "high", "low", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application.

[0035] Example 1

[0036] As Figures 1 to 4The interface evaporation crystallization system for synchronously performing evaporation and fractionated crystallization includes a fractionated crystallization device 200 and a solar heat focusing device 100. The fractionated crystallization device 200 includes an evaporation box 220 and an evaporation crystallization unit 210 arranged in the evaporation box 220. The solar heat focusing device 100 is partially embedded in the fractionated crystallization device 200 to form a heat source in the evaporation box 220. The evaporation crystallization unit 210 is provided with a first porous structure 211 for attracting a salt solution. The first porous structure 211 is provided with a second porous structure 212 for performing interface evaporation and fractionated crystallization of the salt solution. The second porous structure 212 is a controllable nano-porous medium. The evaporation crystallization unit 210 is arranged along the heat radiation direction of the solar heat focusing device 100 to divide the inner cavity of the evaporation box 220 into a plurality of cavities, which are generation cavities for performing interface evaporation and fractionated crystallization. The controllable nano-porous medium is any one or a combination of MXenes, molybdenum disulfide, graphene, graphene oxide, hexagonal boron nitride, a single-element two-dimensional semiconductor, and a two-dimensional van der Waals oxide. In this scheme, the controllable nano-porous medium is attached to the first porous structure 211 as a film assembly. For example, the controllable nano-porous medium is attached to the first porous structure 211 as a two-dimensional graphene oxide film.

[0037] The interface evaporation crystallization system for synchronously performing evaporation and fractionated crystallization of the present embodiment only needs to utilize solar energy and convert it into heat energy to heat the system without other forms of energy input. In combination with the characteristics of the controllable nano-porous medium having molecular sieve and Donnan effect, the salt solution can be partially separated by the controllable nano-porous medium. The present solar heating method and multi-stage gradient heat transfer are combined to realize efficient coupling of evaporation-crystallization-separation and purification by utilizing solar energy, thereby achieving a clean and efficient "zero emission" treatment technology with the advantages of membrane and thermal methods, and achieving the goal of water production and salt separation and crystallization.

[0038] The multi-stage gradient heat transfer is performed in the plurality of generation cavities. The steam transferred by heat is condensed by heat exchange with the next stage interface, and then drives the evaporation and crystallization of the next stage. The evaporation box 220 is preferably made of heat insulation material to reduce heat loss.

[0039] The controllable nano-porous medium is connected to the interface evaporation system and separates the salt solution under the driving of capillary force. Part of the solutes in the salt solution pass through the nanofiltration membrane due to the screening effect and Donnan effect, and the other part is retained at the bottom of the membrane and is not allowed to pass through the nanofiltration membrane, thereby realizing selective separation of solutes.

[0040] For example, the controllable nanoporous medium 4 is a graphene oxide two-dimensional film, and the feed salt solution is a NaCl / Na2SO4 mixed salt solution. Due to the precise regulation of the molecular transport channel by the graphene oxide two-dimensional film and the appropriate interface modification, the effective separation and high-efficiency transport of salt ions can be realized. According to the molecular sieve of nanofiltration and the Donnan effect, when the nanopore has a suitable pore size and the port is negatively charged, Cl - and SO4 2- .

[0041] Part of the first porous structure 211 is arranged in the evaporation box 220, and the other part extends out of the evaporation box 220. The part extending out of the evaporation box 220 is used to guide the salt solution into the part of the first porous structure 211 in the evaporation box 220.

[0042] The first porous structure 211 is made of nylon, and the first porous structure 211 is arranged as a nylon layer. The high-salt solution is driven into the adiabatic evaporation box 220 by capillary force. The first porous structure 211 arranged as a nylon layer also improves the bearing capacity of the controllable nanoporous medium, i.e., the second porous structure 212.

[0043] According to the embodiment, the system uses an interface evaporation crystallization assembly for synchronous evaporation and fractionation crystallization. The assembly uses the controllable nanoporous medium. By precisely regulating the pore size of the nanoporous material and the interface characteristics, water molecules can enter a high-activity, metastable state, which can greatly reduce the phase change latent heat of interface evaporation. Under the premise of fixed solar energy density, studying the phase change behavior of water molecules and reducing the interface phase change latent heat can break this inherent contradiction.

[0044] Embodiment 2

[0045] Based on the above-mentioned embodiment 1, the evaporation crystallization unit 210 of the embodiment further comprises a heat-conducting plate body 213 connected to the inner wall of the evaporation box 220. The first porous structure 211 is connected to the heat-conducting plate body 213, and the heat-conducting plate body 213 is located on the side of the first porous structure 211 close to the heat source. The side of the first porous structure 211 away from the heat source is provided with the second porous structure 212.

[0046] The heat-conducting plate body 213 can be made of copper plate, stainless steel plate, or other materials with good heat-conducting performance. The thickness of the heat-conducting plate body 213 can be set according to the needs, as long as the heat in the evaporation cavity can be transferred to the first porous structure 211. If the first porous structure 211 is made of flexible material, the heat-conducting plate body 213 also plays a supporting role for the first porous structure 211.

[0047] In use, as the evaporation crystallization proceeds, the high-salt solution is transported to the inside of the evaporation interface, i.e. the part of the first porous structure 211 inside the evaporation tank 220, by capillary force. The first porous structure 211 can improve the load capacity of the whole controllable nanoporous medium, and maintain the normal operation of the controllable nanoporous medium separation. Under the driving of capillary force, the controllable nanoporous medium separates the salt solution, and as the process proceeds, the system can continuously perform the evaporation crystallization and separation and purification process. In operation, the vapor exchanges heat with the next stage interface on the heat-conducting plate body 213 (copper plate) to condense and drive the evaporation crystallization of the next stage.

[0048] Embodiment 3

[0049] On the basis of the above-mentioned embodiments 1 or 2, the above-mentioned evaporation cavity is arranged with a recovery tank 230; the feed inlet of the above-mentioned recovery tank 230 corresponds to the plate surface of the heat-conducting plate body 213 or the second porous structure 212 facing the evaporation cavity, for collecting the material on the plate surface. In this way, the material (water or crystal) collected from the heat-conducting plate body 213 or the second porous structure 212 can be conveniently collected. The above-mentioned recovery tank 230 can be arranged close to the heat-conducting plate body 213 or the second porous structure 212 or the inner wall of the evaporation tank 220 (the inner wall of the evaporation tank 220 can be arranged with the heat-conducting plate body 213 at the same time).

[0050] Embodiment 4

[0051] On the basis of any of the above-mentioned embodiments 1 to 3, the solar heat focusing device 100 of the present embodiment comprises a heat-conducting plate 110; a part of the heat-conducting plate 110 extends into the evaporation tank 220, and this part forms the above-mentioned heat source. Since the solar heat focusing can convert solar energy into heat energy, the above-mentioned heat-conducting plate 110 can be a copper plate, which transmits heat energy to the evaporation crystallization unit 210 in contact with the copper plate. The copper plate and the evaporation crystallization unit 210 in contact with the copper plate form a main fractional crystallization system. Through heat transfer, the evaporation interface drives the evaporation of the solution and the crystallization of the salt, and the vapor exchanges heat with the next stage interface to condense and drive the evaporation crystallization of the next stage.

[0052] Specifically, the above-mentioned heat-conducting plate 110 comprises a horizontally arranged upper top plate 111 and a vertically arranged lower insertion plate 112; the lower side of the upper top plate 111 is connected to the upper end of the lower insertion plate 112; the lower insertion plate 112 extends into the evaporation tank 220, and the upper top plate 111 is exposed outside the evaporation tank 220. The upper top plate 111 is provided to ensure sufficient light collection area.

[0053] On the basis of the embodiment, the upper side of the upper top plate 111 is further provided with a light-absorbing coating 120. The light-absorbing coating 120 can efficiently convert solar energy into heat energy. The lower insertion plate 112 is located in the middle of the evaporation tank 220, and the two side surfaces of the lower insertion plate 112 are respectively provided with the first porous structure 211. In this way, the lower insertion plate 112 in the middle of the evaporation tank 220 is used as a heat source to transfer heat to both sides, thereby ensuring efficient use of heat energy.

[0054] Embodiment 5

[0055] On the basis of any of the solutions in Embodiments 1 to 4, the interface evaporation crystallization system for simultaneous evaporation and fractionated crystallization further comprises a feed liquid tank 300 located at the lower side of the evaporation tank 220, and a part of the first porous structure 211 extends into the feed liquid tank 300. The feed liquid tank 300 is provided with a heat insulation plate 310 for dividing the feed liquid tank 300 into two chambers. The heat insulation plate 310 is provided with a channel for connecting the two chambers, and a valve assembly 311 is arranged on the channel. Figure 1 and Figure 2 , Figure 2 FIG. 6 is a partial enlarged view of the evaporation crystallization unit 210 on the right side, and the evaporation crystallization unit 210 on the left side of the lower insertion plate 112 is arranged in a mirror image relative to the lower insertion plate 112.

[0056] The valve assembly 311 is arranged in the middle of the feed liquid tank 300 and is used for discharging the concentrated salt solution to the left side of the solar heat focusing device 100. It can be understood that, as the solute and water molecules on the right side of the solar heat focusing device 100 continuously evaporate and crystallize, the remaining solution continuously concentrates.

[0057] As Figure 1 and Figure 4 When the feed liquid passes through the solar heat focusing device 100 on the right side to transfer heat energy to the evaporation interface to drive the solution to evaporate and crystallize, the crystallization product is generated on the surface of the controllable nano-porous medium, and is collected in the recovery tank 230 at the lower side of the second porous structure 212 after a period of crystallization due to gravity. The water condensed after heat exchange with the next interface also collects in the recovery tank 230 at the lower side of the heat conduction plate (copper plate) due to gravity. After the valve assembly 311 is opened, the concentrated solution is discharged to the other side (the left side of the solar heat focusing device 100) for evaporation crystallization, and the above evaporation crystallization process is repeated.

[0058] The feed liquid tank 300 is selected to be NaCl / Na2SO4 2- The mixed salt solution is the feed salt solution. Due to the molecular sieve and the Donnan effect of the graphene oxide two-dimensional film, Na + , Cl -The water molecules are transported in the membrane channel and evaporate and crystallize at the interface to obtain water vapor and NaCl crystals, and Na2SO4 is retained at the bottom of the membrane. After a period of operation, the valve assembly 311 is opened to allow the Na2SO4 solution retained on the right side of the solar heat focusing device 100 to be discharged to the left side of the solar heat focusing device 100 for interface evaporation and crystallization in the same way as the right side, but no longer needs solute separation.

[0059] According to the arrangement of the scheme of the embodiment, the recovery tank 230 on the right side of the solar heat focusing device 100 can collect NaCl crystals and condensed water, and the recovery tank 230 on the left side of the solar heat focusing device 100 can collect Na2SO4 crystals and condensed water.

[0060] In summary, the above-mentioned various embodiments of the present application can have one or more of the following advantages or benefits:

[0061] (1) The conventional "membrane" treatment technology can realize salt ion separation and purification but cannot deal with the salt crystallization and high osmotic pressure problem of high-salt wastewater. The "heat" treatment technology can recover water resources through evaporation but cannot realize salt separation and purification. The above-mentioned interface evaporation and crystallization system that simultaneously performs evaporation and quality separation and crystallization is a clean and efficient "zero discharge" treatment technology that combines the advantages of membrane and heat methods, and is expected to solve the problems of the existing high-salt wastewater treatment process, such as complex process flow, huge energy consumption, and heavy energy and environmental burden, to ensure clean energy utilization and sustainable social development. In addition, the above-mentioned solar heat focusing device 100 converts solar energy absorption into heat energy, which is a clean and efficient energy utilization method.

[0062] (2) As evaporation and crystallization continuously proceed, the high-salt solution is transported to the bottom of the evaporation interface by capillary force. Under the driving of capillary force, the controllable nanoporous medium separates the salt solution, transports part of the solute and water molecules to the interface for evaporation and crystallization, and discharges the other part of the solute to the other side (the left side of the above-mentioned solar heat focusing device 100) for evaporation and crystallization after being concentrated and retained. As the above-mentioned process continuously proceeds, the left and right sides of the system can continuously perform evaporation and crystallization and separation and purification processes.

[0063] (3) Through the design of a multi-stage interface evaporation system, when the solar heat focusing device 100 transmits heat energy to the first-stage evaporation interface, the following stages can perform heat exchange and condensation with the vapor and the next-stage interface to drive the evaporation and crystallization of the next stage. On the one hand, the multi-stage evaporation arrangement can effectively recover the latent heat of phase change to improve the evaporation and crystallization yield and energy utilization rate, and on the other hand, the evaporated water vapor can be collected.

[0064] The above detailed description of the specific implementation of the present application further illustrates the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above is only a specific implementation of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An interface evaporative crystallization assembly for the simultaneous performance of evaporation and fractionated crystallization, characterized in that, Comprising: a heat-conducting plate body; a first porous structure for attracting a salt solution, the first porous structure being combined to one side of the heat-conducting plate body; a second porous structure, the second porous structure being arranged on the side of the first porous structure away from the heat-conducting plate body, the second porous structure being connected with the first porous structure through the heat-conducting plate body; wherein the second porous structure is a controllable nano-porous medium with a molecular sieve selective channel, for enabling the salt solution attracted by the first porous structure to simultaneously undergo selective evaporation and directional crystallization of different solutes on the surface of the second porous structure; the controllable nano-porous medium is any one or any combination of MXenes, molybdenum disulfide, graphene, graphene oxide, hexagonal boron nitride, single-element two-dimensional semiconductor, and two-dimensional van der Waals oxide. Comprising:

2. An interface evaporative crystallization system for simultaneous evaporation and fractionated crystallization, characterized in that, a separation and crystallization device, the separation and crystallization device comprising an evaporation tank and an evaporation and crystallization unit built in the evaporation tank; a solar heat focusing device, a part of the solar heat focusing device being embedded in the separation and crystallization device to form a heat source in the evaporation tank; wherein the evaporation and crystallization unit is provided with a first porous structure for attracting a salt solution, and the first porous structure is provided with a second porous structure; the second porous structure is a controllable nano-porous medium, for enabling the salt solution attracted by the first porous structure to simultaneously undergo evaporation and separation and crystallization on the interface of the second porous structure; the controllable nano-porous medium is any one or any combination of MXenes, molybdenum disulfide, graphene, graphene oxide, hexagonal boron nitride, single-element two-dimensional semiconductor, and two-dimensional van der Waals oxide; the evaporation and crystallization unit further comprises a heat-conducting plate body connected to the inner wall of the evaporation tank; the first porous structure is connected with the heat-conducting plate body, so that the heat-conducting plate body is located on the side of the first porous structure close to the heat source; the second porous structure is arranged on the side of the first porous structure away from the heat source.

3. The interface evaporation and crystallization system for simultaneously undergoing evaporation and separation and crystallization according to claim 2, wherein the evaporation and crystallization unit is arranged in the direction of heat radiation of the solar heat focusing device, so as to divide the inner cavity of the evaporation tank into a plurality of cavities, and the cavities are generation cavities for simultaneously undergoing interface evaporation and separation and crystallization.

4. The interface evaporation and crystallization system for simultaneously undergoing evaporation and separation and crystallization according to claim 3, wherein a recovery groove is arranged in the generation cavity; the feeding port of the recovery groove corresponds to the plate surface of the heat-conducting plate body or the second porous structure facing the generation cavity, for collecting the materials on the plate surface.

5. The interface evaporation and crystallization system for simultaneously undergoing evaporation and separation and crystallization according to claim 2, wherein a part of the first porous structure is built in the evaporation tank, and the other part of the first porous structure extends out of the evaporation tank, and the part extending out of the evaporation tank is used for guiding the salt solution into the part of the first porous structure located in the evaporation tank.

6. The interface evaporation and crystallization system for simultaneously undergoing evaporation and separation and crystallization according to claim 2, wherein the solar heat focusing device comprises a heat transfer plate; the part of the heat transfer plate extending into the evaporation tank forms the heat source. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7. The system according to claim 6, wherein the heat transfer plate comprises a horizontally arranged upper roof and a vertically arranged lower plug; the lower side of the upper roof is connected with the upper end of the lower plug; the lower plug extends into the evaporation tank, and the upper roof is exposed outside the evaporation tank.

8. The system according to claim 7, wherein the lower plug is located in the middle of the evaporation tank; the two side surfaces of the lower plug are respectively provided with the first porous structure.

9. The system according to any one of claims 2-8, further comprising a feed liquid tank located at the lower side of the evaporation tank, and a part of the first porous structure extends into the feed liquid tank; the feed liquid tank is provided with a heat insulation plate for dividing the feed liquid tank into two chambers; the heat insulation plate is provided with a passage for connecting the two chambers, and the passage is provided with a valve assembly. ​ ​ ​

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