A secondary seawater desalination device and method of use

Abstract

The application relates to a secondary seawater desalination device and a use method, and relates to the technical field of seawater desalination. On one hand, the device comprises an evapotranspiration chamber and a heat permeation chamber. A capillary evapotranspiration assembly is arranged in the evapotranspiration chamber, the capillary evapotranspiration assembly divides the evapotranspiration chamber into a steam cavity and a seawater cavity, the capillary evapotranspiration assembly is used for forming steam by capillary evaporation of seawater in the seawater cavity and entering the steam cavity; a heat permeation membrane is arranged in the heat permeation chamber, the heat permeation membrane divides the heat permeation chamber into a secondary desalination cavity and a desalinated seawater cavity, the secondary desalination cavity is communicated with the steam cavity, the desalinated seawater cavity is communicated with the seawater cavity, and the heat permeation membrane is used for absorbing fresh water from desalinated seawater with a temperature lower than a first set temperature in the desalinated seawater cavity and discharging fresh water under the action of steam with a temperature higher than a second set temperature in the secondary desalination cavity. On the second aspect, a method for using the device is provided. By coupling the evapotranspiration chamber and the heat permeation chamber, seawater is subjected to secondary desalination, fresh water is synchronously generated in the evapotranspiration chamber and the heat permeation chamber, and the desalination efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of seawater desalination technology, specifically to a secondary seawater desalination device and its usage method. Background Technology

[0002] The essence of seawater desalination is exchanging energy for water. The contradiction between the ever-increasing demand for freshwater and the shortage of energy is the bottleneck problem restricting the rapid development of seawater desalination technology. Obtaining the most freshwater with the least amount of energy is the most anticipated desalination method.

[0003] Currently, the main methods of seawater desalination are broadly classified into membrane methods and distillation methods. Membrane methods primarily utilize reverse osmosis, while the most common distillation methods include multi-stage flash distillation, multi-effect distillation, and compressed gas distillation. Regardless of the method used, the separation of salt and water is a non-spontaneous process that requires energy. In practice, the optimal solution must be selected based on factors such as scale, energy costs, raw water quality, climate conditions, and technical and safety requirements.

[0004] Existing thermal seawater desalination plants mostly use multiple evaporation chambers connected in series to reuse the steam from one stage as a heat source for the next, achieving multiple uses of energy to produce multiple units of fresh water. However, these desalination devices use large evaporation chambers, and the array of multiple chambers requires a large floor space, is cumbersome, and has high costs, failing to meet manufacturers' needs. While membrane distillation technology can use hot water at only 40°C, the desalinated steam still requires a large amount of cooling water. In recent years, capillary seawater desalination technology has emerged, which can recover waste heat energy with a relative temperature difference of only 4°C or more from the environment. Because there is a large amount of low-temperature waste hot water in industry, capillary desalination technology achieves true waste heat utilization and can reduce energy costs on a large scale. However, a drawback of capillary seawater desalination technology is that, like membrane distillation technology, the low-temperature steam still requires a large amount of cooling water for cooling, resulting in high costs on the condensation side. Summary of the Invention

[0005] In view of the deficiencies in the existing technology, the purpose of this invention is to provide a secondary seawater desalination device and a secondary seawater desalination method to solve the problems of high cost and low seawater desalination efficiency in the capillary seawater desalination process.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, embodiments of this application provide a secondary seawater desalination device, comprising:

[0008] An evaporation chamber is provided with a capillary evaporation assembly, which divides the evaporation chamber into a steam chamber and a seawater chamber. The capillary evaporation assembly is used to convert seawater in the seawater chamber into steam through capillary evaporation and then enter the steam chamber.

[0009] A heat permeation chamber is provided with a heat permeation membrane, which divides the heat permeation chamber into a secondary desalination chamber and a freshwater chamber. The secondary desalination chamber is connected to the steam chamber, and the freshwater chamber is connected to the seawater chamber. The heat permeation membrane is used to draw freshwater from the freshwater chamber at a temperature lower than a first set temperature and to release freshwater under the action of steam at a temperature higher than a second set temperature in the secondary desalination chamber. The secondary desalination chamber has a drain outlet for discharging freshwater.

[0010] The first set temperature is lower than the working temperature at which the thermal osmosis membrane absorbs fresh water, while the second set temperature is higher than the working temperature at which the thermal osmosis membrane releases fresh water.

[0011] In conjunction with the first aspect, in one embodiment, the capillary evaporation assembly includes a capillary layer and a heat exchange tube bundle, the heat exchange tube bundle being located on top of the capillary layer such that the heat exchange tube bundle is located on one side of the steam chamber and the capillary layer is located on one side of the seawater chamber, the heat exchange tube bundle being used to communicate with a heat source.

[0012] In conjunction with the first aspect, in one embodiment, the capillary layer and the heat exchange tube bundle are bonded together by sintering.

[0013] In conjunction with the first aspect, in one embodiment, the aforementioned thermal osmosis membrane comprises:

[0014] The device comprises a hydrophobic and breathable membrane and a thermosensitive functional material. The thermosensitive functional material is located on top of the hydrophobic and breathable membrane, such that the thermosensitive functional material is positioned on one side of the secondary desalination chamber, and the hydrophobic and breathable membrane is positioned on one side of the freshwater chamber. The hydrophobic and breathable membrane is used to desalinate freshwater that has been subjected to capillary evaporation and is below a first set temperature, driven by the pressure difference across the membrane. The thermosensitive functional material is used to absorb freshwater and, upon entering the secondary desalination chamber, undergoes a phase change by absorbing heat under the heating of steam at a temperature higher than a second set temperature, releasing freshwater.

[0015] In conjunction with the first aspect, in one embodiment, the aforementioned heat-sensitive functional material is uniformly laid on the aforementioned hydrophobic and breathable membrane.

[0016] In conjunction with the first aspect, in one embodiment, the above-described apparatus further includes a control component, the control component comprising:

[0017] A temperature sensor is located inside the aforementioned secondary desalination chamber;

[0018] A control valve is provided on the pipeline connecting the steam chamber and the secondary desalination chamber and is connected to the temperature sensor signal. It is used to close the control valve when the secondary desalination chamber rises to the third set temperature for the first set time, and to open the control valve when the temperature of the secondary desalination chamber drops to the fourth set temperature for the second set time, or drops to the working temperature of the heat permeation membrane for water absorption.

[0019] The fourth set temperature is higher than the working temperature of the heat permeation membrane for water absorption, and the third set temperature is lower than the steam temperature in the steam chamber.

[0020] Secondly, embodiments of this application provide a method for secondary seawater desalination, implemented using any of the secondary seawater desalination devices described above, comprising the following steps:

[0021] Seawater is transported into the seawater chamber, where it is converted into steam by the capillary evaporation assembly and then enters the steam chamber.

[0022] After being subjected to capillary evaporation, the fresh seawater enters the fresh seawater chamber. Steam enters the secondary desalination chamber. The heat permeation membrane draws in fresh water from the fresh seawater in the fresh seawater chamber, which is at a temperature lower than the first set temperature. Under the action of steam entering the secondary desalination chamber at a temperature higher than the second set temperature, the fresh water is released and discharged from the drain outlet.

[0023] In conjunction with the second aspect, in one embodiment, the thermal osmosis membrane draws fresh water from the freshwater in the aforementioned freshwater cavity at a temperature lower than a first set temperature, and releases the fresh water under the action of steam entering the aforementioned secondary desalination cavity at a temperature higher than a second set temperature, comprising:

[0024] The fresh seawater, which has been evaporated by capillary action and is below the first set temperature, is desalinated a second time under the pressure difference between the two sides of the hydrophobic and breathable membrane.

[0025] After the heat-sensitive functional material absorbs fresh water, it undergoes an endothermic phase change and releases fresh water when heated by steam at a temperature higher than the second set temperature in the secondary desalination chamber.

[0026] In conjunction with the second aspect, in one implementation, it further includes:

[0027] Obtain the temperature inside the secondary desalination chamber mentioned above;

[0028] When the temperature in the secondary desalination chamber rises to the third set temperature and the first set time, the control valve is closed and the fresh water is discharged.

[0029] When the temperature in the secondary desalination chamber drops to the fourth set temperature for the second set time or to the working temperature of the heat osmosis membrane for water absorption, the control valve is opened.

[0030] The fourth set temperature is higher than the working temperature of the heat permeation membrane for water absorption, while the third set temperature is lower than the steam temperature in the steam chamber.

[0031] In conjunction with the second aspect, in one embodiment, the operating temperature for the above-mentioned heat osmosis membrane to absorb water is 30–40°C.

[0032] The beneficial effects of the technical solution provided in this application include: by coupling the evaporation chamber and the heat infiltration chamber, seawater is first desalinated in the evaporation chamber through capillary evaporation, and then the fresh seawater is desalinated again in the heat infiltration chamber. The evaporation chamber and the heat infiltration chamber operate cyclically to achieve synchronous production of fresh water and improve the desalination efficiency. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of a secondary seawater desalination device according to the present invention.

[0035] In the diagram: 1. Evaporation chamber; 10. Capillary evaporation assembly; 101. Capillary layer; 102. Heat exchange tube bundle; 11. Steam chamber; 12. Seawater chamber; 2. Heat permeation chamber; 20. Heat permeation membrane; 201. Hydrophobic and breathable membrane; 202. Thermosensitive functional material; 21. Secondary desalination chamber; 211. Drain outlet; 22. Freshwater and seawater chamber; 221. Discharge outlet; 31. Temperature sensor; 32. Control valve. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0037] On the one hand, the embodiments of this application provide a secondary seawater desalination device, which can solve the problem in the prior art that the waste heat of steam generated after desalination cannot be utilized, resulting in high condensation costs and low desalination efficiency.

[0038] like Figure 1As shown, the secondary seawater desalination device of this application includes an evaporation chamber 1 and a heat permeation chamber 2. The evaporation chamber 1 is equipped with a capillary evaporation component 10, which divides the evaporation chamber 1 into a steam chamber 11 and a seawater chamber 12. The capillary evaporation component 10 is used to convert seawater in the seawater chamber 12 into steam through capillary evaporation and then enter the steam chamber 11. The heat permeation chamber 2 is equipped with a heat permeation membrane 20, which divides the heat permeation chamber 2 into a secondary desalination chamber 21 and a freshwater chamber 22. The secondary desalination chamber 21 is connected to the steam chamber 11, and the freshwater chamber 22 is connected to the seawater chamber 12. The heat permeation membrane 20 is used to draw in freshwater from the freshwater chamber 22 at a temperature lower than a first set temperature, and to release the freshwater under the action of steam at a temperature higher than a second set temperature in the secondary desalination chamber 21. The secondary desalination chamber 21 has a drain outlet 211 for discharging freshwater. The first set temperature is lower than the working temperature at which the heat permeation membrane 20 draws in freshwater, and the second set temperature is higher than the working temperature at which the heat permeation membrane 20 releases freshwater.

[0039] In other words, seawater undergoes initial desalination in the evaporation chamber 1 through capillary evaporation. At this time, there is a temperature difference between the steam chamber 11 and the seawater chamber 12 due to capillary evaporation, with the steam temperature in the steam chamber 11 being higher than that in the seawater chamber 12. After the steam in the steam chamber 11 undergoes capillary evaporation and enters the secondary desalination chamber 21, and the fresh seawater in the seawater chamber 12 undergoes capillary evaporation and enters the fresh seawater chamber 22, the heat permeation membrane 20 performs secondary desalination of the fresh seawater. The residual heat of the steam in the secondary desalination chamber 21 is used to heat the heat permeation membrane 20 to release fresh water.

[0040] Therefore, it can be seen that secondary desalination is achieved by subjecting seawater to capillary evaporation and membrane distillation, thereby improving the desalination efficiency. In this embodiment, the heat permeation membrane 20 not only plays a role in seawater desalination, but also transfers the residual heat of the steam in the secondary desalination chamber 21 to the seawater in the freshwater chamber 22 through heat exchange, thus playing a role in cooling and condensing the steam.

[0041] It should be noted that the seawater in the seawater chamber 12 and the freshwater chamber 22 can be continuously flowing. The freshwater in the freshwater chamber 22, after heat exchange, is discharged through the outlet 221 to continuously cool the secondary desalination chamber 21. Alternatively, when the temperatures in the secondary desalination chamber 21 and the freshwater chamber 22 are the same, the freshwater in the seawater chamber 12 is then flowed into the freshwater chamber 22. The evaporation chamber 1 and the heat infiltration chamber 2 operate cyclically to achieve synchronous freshwater production.

[0042] In some optional embodiments, the capillary evaporation assembly 10 includes a capillary layer 101 and a heat exchange tube bundle 102, the heat exchange tube bundle 102 being located on top of the capillary layer 101 such that the heat exchange tube bundle 102 is located on one side of the steam chamber 11 and the capillary layer 101 is located on one side of the seawater chamber 12, and the heat exchange tube bundle 102 is used to communicate with a heat source.

[0043] It is understood that multiple heat exchange tube bundles 102 are provided, made of a material with high thermal conductivity. One end of the heat exchange tube bundle 102 is used to connect to a heat source, and the capillary layer 101 is composed of several capillary materials. Seawater entering the seawater cavity 12 is transported to the outer wall of the heat exchange tube bundle 102 under the action of the capillary layer. The seawater is heated and evaporated on the outside of the heat exchange tube bundle 102 to generate steam, which enters the steam cavity 11.

[0044] Due to capillary evaporation, seawater can boil violently at low temperatures, thus utilizing industrial waste heat below 60°C, such as low-grade heat energy from industrial wastewater and exhaust gases, thereby improving energy utilization. Taking advantage of the space between the heat exchange tube bundle 102 and the capillary layer 101, the tube bundle can easily combine with waste heat, while the capillary material can provide seawater to the tube bundle, ensuring uniform liquid replenishment without the need for pumping.

[0045] Optionally, the capillary material is made of corrosion-resistant metal powder or hydrophilic polymer powder; the heat exchange tube bundle is made of a material with high thermal conductivity, including titanium, aluminum and brass.

[0046] In some alternative embodiments, the capillary layer 101 and the heat exchange tube bundle 102 are bonded together by sintering.

[0047] It is understandable that the heat exchange tube bundle 102 and the capillary layer 101 can be tightly bonded together after sintering, thereby reducing the heat transfer temperature difference introduced by other heat exchange methods.

[0048] In some optional embodiments, the aforementioned heat-permeable membrane 20 includes a hydrophobic and breathable membrane 201 and a thermosensitive functional material 202. The thermosensitive functional material 202 is located on top of the hydrophobic and breathable membrane 201, such that the thermosensitive functional material 202 is located on one side of the secondary desalination chamber 21, and the hydrophobic and breathable membrane 201 is located on one side of the freshwater chamber 22. The hydrophobic and breathable membrane 201 is used to desalinate the freshwater that has been subjected to capillary evaporation and is below a first set temperature, driven by the pressure difference across the two sides of the hydrophobic and breathable membrane 201. The thermosensitive functional material 202 is used to absorb freshwater and, after being heated by steam above a second set temperature in the secondary desalination chamber 21, to absorb heat and undergo a phase change, releasing freshwater.

[0049] Understandably, the hydrophobic and breathable membrane 201 uses a hydrophobic microporous membrane to separate the freshwater solution from the freshwater cavity 22 after capillary evaporation. Due to the surface tension of water, liquid water cannot pass through the micropores of the membrane under normal pressure, while water vapor can. Therefore, when there is a certain temperature difference on both sides of the membrane, due to the difference in vapor pressure, water vapor molecules pass through the micropores and condense on the other side, causing the solution to gradually concentrate. Since there is a temperature and pressure difference between the secondary desalination cavity 21 and the freshwater cavity 22, under the drive of partial pressure, water molecules in the freshwater will diffuse from one side of the freshwater cavity 22 through the hydrophobic and breathable membrane 201 to the other side of the thermosensitive functional material 202. The thermosensitive functional material 202 absorbs the water vapor formed by the volatilization of freshwater during membrane distillation, and under the heating at the second set temperature in the secondary desalination cavity 21, it absorbs heat and changes phase, thereby releasing freshwater.

[0050] As can be seen, the brine is absorbed by the thermosensitive functional material 202 through the hydrophobic and breathable membrane 201 via vapor diffusion. Heat migrates from the brine to the thermosensitive functional material 202, causing the seawater to cool while the material heats up. Uniquely, this scheme utilizes the hydrophobic and breathable membrane 201 as a plate heat exchanger. The heat absorbed by the thermosensitive functional material 202 is then transferred to the brine through the membrane, maintaining a constant temperature and achieving transmembrane vapor transfer. When the thermosensitive functional material 202 becomes saturated, the evaporating steam is used to heat it. After absorbing heat, the material releases the absorbed water, and the evaporating steam condenses into fresh water. This process operates cyclically, enabling the two modules to simultaneously produce fresh water.

[0051] It should be noted that the heat-sensitive functional material 202 undergoes a phase change and releases fresh water when it reaches or approaches the second set temperature, and absorbs water vapor when it is at or below the first set temperature.

[0052] Preferably, the thermosensitive functional material 202 is a material that exhibits water absorption / release characteristics when stimulated by temperature, such as a thermosensitive hydrogel.

[0053] In some alternative embodiments, the above-mentioned heat-sensitive functional material 202 is uniformly laid on the above-mentioned hydrophobic and breathable membrane 201.

[0054] Optionally, the heat-sensitive functional material 202 is spread on the surface of the hydrophobic and breathable membrane 201 with a thickness of 5-10 mm.

[0055] In some optional embodiments, the aforementioned secondary seawater desalination device further includes a control component, which includes a temperature sensor 31 and a control valve 32. Specifically, the temperature sensor 31 is located inside the secondary desalination chamber 21; the control valve 32 is located on the pipeline connecting the steam chamber 11 and the secondary desalination chamber 21, and is signal-connected to the temperature sensor 31. The control valve 32 is used to close when the secondary desalination chamber 21 rises to a third set temperature for a first set time, and to open when the temperature of the secondary desalination chamber 21 drops to a fourth set temperature for a second set time, or to the operating temperature of the heat permeation membrane 20 for water absorption; wherein the fourth set temperature is higher than the operating temperature of the heat permeation membrane 20 for water absorption, and the third set temperature is lower than the steam temperature inside the steam chamber 11.

[0056] Understandably, in order to achieve efficient and continuous secondary desalination of seawater, a control valve 32 is installed on the pipeline connecting the steam chamber 11 and the secondary desalination chamber 21. When the temperature of the secondary desalination chamber 21 drops to the fourth set temperature for the second set time, or to the working temperature at which the heat-permeable membrane 20 absorbs water, the brine is absorbed by the heat-sensitive functional material 202 through the hydrophobic and breathable membrane 201 in the form of vapor diffusion, and absorbs water within the second set time. At this time, the control valve 32 is opened, allowing water vapor in the steam chamber 11 to enter the secondary desalination chamber 21. As heat migrates from the fresh seawater to the heat-sensitive functional material 202, the seawater cools while the heat-sensitive functional material heats up, and the secondary desalination chamber 21... The evaporating steam in chamber 1 heats the heat-sensitive functional material 202, causing it to undergo a phase change at the third temperature and release the absorbed water. Simultaneously, the evaporating steam condenses to form fresh water. When the valve is opened, the temperature in the secondary desalination chamber 21 rises to the third set temperature for a first set time. At this point, the heat-sensitive functional material 202 completely releases the water. The valve is then closed, and the heat-sensitive functional material 202 exchanges heat with the fresh seawater, thereby lowering the temperature to the fourth set temperature. After the phase change, it continues to absorb water.

[0057] It should be noted that before the heat-sensitive functional material 202 exchanges heat with the fresh seawater to reduce the temperature to the fourth set temperature, the fresh water in the secondary desalination chamber 21 should be discharged from the drain outlet 211 in a timely manner.

[0058] Under a heat extraction capacity of 1MW, a standalone evaporation unit can produce 400kg of water, a standalone membrane distillation unit can produce 380kg of water, while the secondary seawater desalination unit of this application can produce 8000kg of water. This achieves a 20-fold increase in seawater desalination output and a 50% reduction in power consumption.

[0059] On the other hand, this application also provides a method for secondary seawater desalination, implemented using any of the above-mentioned secondary seawater desalination devices, comprising the following steps:

[0060] S1: Seawater is transported into the seawater chamber 12, where it is converted into steam through the capillary evaporation component 10 and enters the steam chamber 11.

[0061] It is understood that the secondary seawater desalination device includes an evaporation chamber 1 and a heat permeation chamber 2. The evaporation chamber 1 is equipped with a capillary evaporation component 10, which divides the evaporation chamber 1 into a steam chamber 11 and a seawater chamber 12. The heat permeation chamber 2 is equipped with a heat permeation membrane 20, which divides the heat permeation chamber 2 into a secondary desalination chamber 21 and a freshwater chamber 22. The secondary desalination chamber 21 is connected to the steam chamber 11, and the freshwater chamber 22 is connected to the seawater chamber 12.

[0062] After the seawater is transported into the seawater chamber 12, it undergoes initial desalination in the evaporation chamber 1 through capillary evaporation.

[0063] Specifically, the capillary evaporation assembly 10 includes a capillary layer 101 and a heat exchange tube bundle 102. The heat exchange tube bundle 102 is located on top of the capillary layer 101, so that the heat exchange tube bundle 102 is located on one side of the steam chamber 11 and the capillary layer 101 is located on one side of the seawater chamber 12. The heat exchange tube bundle 102 is used to communicate with a heat source.

[0064] Seawater entering the seawater chamber 12 is transported to the outer wall of the heat exchange tube bundle 102 by the capillary layer. The capillary layer 101 provides seawater to the heat exchange tube bundle 102. The seawater is heated and evaporated outside the heat exchange tube bundle 102 to generate steam, which enters the steam chamber 11.

[0065] S2: After capillary evaporation, the fresh seawater enters the fresh seawater chamber 22, and the steam enters the secondary desalination chamber 21. The heat permeation membrane 20 draws fresh water from the fresh seawater in the fresh seawater chamber 22, which is at a temperature lower than the first set temperature, and releases the fresh water under the action of the steam in the secondary desalination chamber 21, which is at a temperature higher than the second set temperature. The fresh water is discharged from the drain outlet 211.

[0066] In some optional embodiments, step S2 above includes:

[0067] S21: The fresh seawater, which has been cooled to a temperature below the first set temperature after capillary evaporation, is desalinated a second time under the pressure difference across the hydrophobic and breathable membrane 201.

[0068] S22: After the above-mentioned heat-sensitive functional material 202 absorbs fresh water, it undergoes a phase change due to the heat absorption of steam at a temperature higher than the second set temperature in the above-mentioned secondary desalination chamber 21, and releases fresh water.

[0069] It is understood that the aforementioned heat-permeable membrane 20 includes a hydrophobic and breathable membrane 201 and a thermosensitive functional material 202. The thermosensitive functional material 202 is located on top of the hydrophobic and breathable membrane 201, so that the thermosensitive functional material 202 is located on one side of the secondary desalination chamber 21, and the hydrophobic and breathable membrane 201 is located on one side of the freshwater cavity 22. The hydrophobic and breathable membrane 201 uses a hydrophobic microporous membrane to separate the freshwater solution in the freshwater cavity 22 after capillary evaporation. Due to the surface tension of water, liquid water cannot pass through the micropores of the membrane under normal pressure, while water vapor can. Therefore, when there is a certain temperature difference on both sides of the membrane, due to the difference in vapor pressure, water vapor molecules pass through the micropores and condense on the other side, causing the solution to gradually concentrate. Because of the temperature and pressure difference between the secondary desalination chamber 21 and the freshwater chamber 22, water molecules in the freshwater will diffuse from one side of the freshwater chamber 22 to the other side of the thermosensitive functional material 202 through the hydrophobic and breathable membrane 201 under the drive of partial pressure. The thermosensitive functional material 202 absorbs the water vapor formed by the volatilization of freshwater during membrane distillation, and under the heating of the second set temperature in the secondary desalination chamber 21, it absorbs heat and changes phase, thereby releasing freshwater.

[0070] It should be noted that the heat-sensitive functional material 202 undergoes a phase change and releases fresh water when it reaches or approaches the second set temperature, and absorbs water vapor when it is at or below the first set temperature.

[0071] In some optional embodiments, when the above-mentioned secondary seawater desalination device further includes a control component, which includes a temperature sensor 31 and a control valve 32, the above-mentioned secondary seawater desalination method further includes:

[0072] Obtain the temperature inside the secondary desalination chamber 21;

[0073] When the temperature in the secondary desalination chamber 21 rises to the third set temperature for the first set time, the control valve 32 is closed and the fresh water is discharged.

[0074] When the temperature in the secondary desalination chamber 21 drops to the fourth set temperature for the second set time or to the working temperature at which the heat permeation membrane 20 absorbs water, the control valve 32 is opened.

[0075] The fourth set temperature is higher than the working temperature of the heat osmosis membrane 20 when it absorbs water, and the third set temperature is lower than the steam temperature in the steam chamber 11.

[0076] In other words, the third set temperature is higher than or equal to the phase transition temperature of the thermosensitive functional material 202 of the heat osmosis membrane 20. At this temperature, the thermosensitive functional material 202 no longer absorbs water but discharges fresh water; the fourth set temperature is lower than or equal to the phase transition temperature of the thermosensitive functional material 202 of the heat osmosis membrane 20. At this temperature, the thermosensitive functional material 202 absorbs water.

[0077] In this example, the operating temperature of the aforementioned heat osmosis membrane 20 for water absorption is 30–40°C. Optionally, the third set temperature is 40°C, and the fourth set temperature is 30°C.

[0078] This invention discloses a secondary seawater desalination device and method, in which seawater undergoes initial desalination in the evaporation chamber 1 through capillary evaporation, and then undergoes secondary desalination in the heat permeation chamber 2. The evaporation chamber 1 and the heat permeation chamber 2 operate cyclically to achieve simultaneous freshwater production, thereby improving desalination efficiency. Utilizing the advantages between the heat exchange tube bundle 102 and the capillary layer 101, the tube bundle can easily combine with waste heat, while the capillary material can provide seawater to the tube bundle, ensuring uniform replenishment, eliminating the need for pumps, and reducing desalination energy consumption. By installing a temperature sensor in the secondary desalination chamber 21 and a control valve 32 on the pipeline connecting the steam chamber 11 and the secondary desalination chamber 21, efficient and continuous secondary desalination of seawater is achieved.

[0079] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0080] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0081] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A secondary seawater desalination device, characterized by, The application relates to a seawater desalination device, which comprises the following components: a transpiration chamber (1) provided with a capillary transpiration assembly (10), the capillary transpiration assembly (10) separating the transpiration chamber (1) into a steam cavity (11) and a seawater cavity (12), the capillary transpiration assembly (10) being used for forming steam from seawater in the seawater cavity (12) through capillary evaporation and entering the steam cavity (11); a thermal penetration chamber (2) provided with a thermal penetration membrane (20), the thermal penetration membrane (20) separating the thermal penetration chamber (2) into a secondary desalination cavity (21) and a desalinated seawater cavity (22), the secondary desalination cavity (21) being communicated with the steam cavity (11), the desalinated seawater cavity (22) being communicated with the seawater cavity (12), the thermal penetration membrane (20) being used for absorbing fresh water from desalinated seawater in the desalinated seawater cavity (22) below a first set temperature and discharging fresh water under the action of steam in the secondary desalination cavity (21) above a second set temperature, the secondary desalination cavity (21) being provided with a water outlet (211) for discharging fresh water; wherein the first set temperature is lower than the working temperature of the thermal penetration membrane (20) for absorbing fresh water, and the second set temperature is higher than the working temperature of the thermal penetration membrane (20) for discharging fresh water; the thermal penetration membrane (20) comprising: a hydrophobic air-permeable membrane (201) and a thermal sensitive functional material (202), the thermal sensitive functional material (202) being located on the top of the hydrophobic air-permeable membrane (201) so that the thermal sensitive functional material (202) is located on the side of the secondary desalination cavity (21), the hydrophobic air-permeable membrane (201) being located on the side of the desalinated seawater cavity (22), the hydrophobic air-permeable membrane (201) being used for secondary desalination of desalinated seawater below the first set temperature after capillary evaporation under the pressure difference between the two sides of the hydrophobic air-permeable membrane (201), and the thermal sensitive functional material (202) being used for absorbing fresh water and discharging fresh water through heat absorption and phase change under the action of steam in the secondary desalination cavity (21) above the second set temperature; the thermal sensitive functional material (202) being a material with water absorption / release characteristics under temperature stimulation, which is a thermal sensitive hydrogel.

2. The secondary seawater desalination device of claim 1, wherein, the capillary transpiration assembly (10) comprising a capillary layer (101) and a heat exchange pipe bundle (102), the heat exchange pipe bundle (102) being located on the top of the capillary layer (101) so that the heat exchange pipe bundle (102) is located on the side of the steam cavity (11), and the capillary layer (101) is located on the side of the seawater cavity (12), the heat exchange pipe bundle (102) being used for being communicated with a heat source.

3. The secondary seawater desalination device of claim 2, wherein, the capillary layer (101) and the heat exchange pipe bundle (102) being combined through sintering.

4. The secondary seawater desalination device of claim 1, wherein, the thermal sensitive functional material (202) being uniformly laid on the hydrophobic air-permeable membrane (201).

5. The secondary seawater desalination device of claim 1, wherein, the device further comprises a control assembly, which comprises: a temperature sensor (31) arranged in the secondary desalination cavity (21). a control valve (32) disposed on a pipeline connecting the steam chamber (11) and the secondary desalination chamber (21) and connected to the temperature sensor (31) in signal, for closing the control valve (32) when the secondary desalination chamber (21) rises to a third set temperature for a first set time, and opening the control valve (32) when the temperature of the secondary desalination chamber (21) drops to a fourth set temperature for a second set time, or drops to the working temperature of the heat permeable membrane (20) for water absorption; wherein the fourth set temperature is higher than the working temperature of the heat permeable membrane (20) for water absorption, and the third set temperature is lower than the steam temperature in the steam chamber (11).

6. A method of secondary seawater desalination, characterized by, Implementing the secondary seawater desalination device according to any one of claims 1-5, comprising the following steps: delivering seawater into the seawater chamber (12) to form steam through the capillary evaporation assembly (10) and into the steam chamber (11); after the capillary evaporation, the desalinated seawater enters the desalinated seawater chamber (22), the steam enters the secondary desalination chamber (21), the heat permeable membrane (20) absorbs fresh water from the desalinated seawater in the desalinated seawater chamber (22) below the first set temperature, and releases fresh water under the action of steam in the secondary desalination chamber (21) above the second set temperature, and the fresh water is discharged from the water outlet (211).

7. The method of claim 6, wherein, the heat permeable membrane (20) absorbs fresh water from the desalinated seawater in the desalinated seawater chamber (22) below the first set temperature, and releases fresh water under the action of steam in the secondary desalination chamber (21) above the second set temperature, comprising: the desalinated seawater after capillary evaporation below the first set temperature is driven by the pressure difference between the two sides of the hydrophobic air-permeable membrane (201) for secondary desalination; after the heat-sensitive functional material (202) absorbs fresh water, under the warming of steam in the secondary desalination chamber (21) above the second set temperature, the heat-sensitive functional material (202) absorbs heat and releases fresh water.

8. The method of claim 6, wherein, further comprising: obtaining the temperature in the secondary desalination chamber (21); when the temperature in the secondary desalination chamber (21) rises to a third set temperature for a first set time, closing the control valve (32) and discharging fresh water; when the temperature in the secondary desalination chamber (21) drops to a fourth set temperature for a second set time, or drops to the working temperature of the heat permeable membrane (20) for water absorption, opening the control valve (32); wherein the fourth set temperature is higher than the working temperature of the heat permeable membrane (20) for water absorption, and the third set temperature is lower than the steam temperature in the steam chamber (11).

9. The method of claim 8, wherein, The working temperature of the heat permeable membrane (20) for water absorption is 30-40℃.

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