Inverted solar multi-stage evaporation water purifier

Abstract

Disclosed in the embodiments of the present invention is an inverted solar multi-stage evaporation water purifier, comprising a multi-stage evaporator, wherein a housing is provided outside the multi-stage evaporator; the multi-stage evaporator is connected, at an opening provided at the top end thereof, to a raw water tank by means of a pipeline; and a condenser is arranged below the multi-stage evaporator. The multi-stage evaporator comprises a heating disk at the bottommost layer, and a plurality of evaporation disks are arranged directly above the heating disk; the heating disk and each evaporation disk are respectively provided with an evaporation cloth on the upper surface thereof; the heating disk and each evaporation disk are respectively provided with a hole on the top end thereof; the heating disk and each evaporation disk are respectively provided with a baffle on the top of the outer side thereof, and each evaporation disk is provided with a sealing drainage cloth at the bottom of the outer side thereof, and the upper portion of each baffle is in contact with the bottom of the sealing drainage cloth; and the heating disk and each evaporation disk are further provided respectively with a drainage water outlet at the edge thereof. In the embodiments of the present invention, the water production efficiency is high, there is no need for frequent maintenance due to having a self-cleaning function, and the energy utilization rate is high, thus having a low cost.

Description

Inverted solar multi-stage evaporation water purifier

[0001] The present application claims priority to the Chinese patent application No. 202410676737.9, filed on May 29, 2024, and entitled "Inverted solar multi-stage evaporation water purifier". TECHNICAL FIELD

[0002] The present application belongs to the technical field of water purification, and relates to an inverted solar multi-stage evaporation water purifier. BACKGROUND

[0003] Solar water purification is a potential solution to the shortage of fresh water and energy crisis, as its energy is a sustainable clean energy. In recent years, solar water purification technology has been developed, including enhanced light absorption, desalination, reduction of water latent heat to increase evaporation, recovery of latent heat to suppress heat loss, etc. Among them, multi-stage solar still (MSS) has become a promising technology in fresh water supply, wastewater and brine management due to its zero carbon characteristics. Multi-stage solar still not only improves steam generation efficiency by recovering latent heat, but also condenses steam to produce fresh water at the same time. However, the current multi-stage solar still still has problems such as complex structure, low water production per unit area, high investment cost, easy concentration and precipitation of dissolved substances such as salt, inability to run continuously for a long time, and unsuitability for long-term operation of devices required in waste heat utilization. For example, the technologies disclosed in Chinese patents: CN116495816A, CN217458892U, and CN107720863A. Therefore, no commercial multi-stage solar still products have been seen.

[0004] In addition, the payback period of the prior art is very long, especially it cannot be applied in remote areas with insufficient funds.

[0005] Increasing the energy input density through a concentrator is an effective means to reduce the cost of the device, but the condensation efficiency lacks effective means, the latent heat is not fully utilized, and the water production efficiency is still limited, usually the water production is less than 2.5 L kWh -1 , and the daily water production per unit area of the evaporation water purifier is not more than 40 L m -2 .

[0006] On the other hand, in the prior art, when the solar radiation power is too low, the ordinary solar water purifier cannot work at all, because the driving energy input is insufficient, and the water evaporation is too slow to lose the working ability. TECHNICAL PROBLEM

[0007] In order to achieve the above purpose, the present application provides an inverted solar multi-stage evaporation water purifier, which has high water production efficiency, self-cleaning function, high energy utilization rate, and low cost. Technical solutions

[0008] The technical scheme adopted by the present application is a multi-stage evaporation water purifier, comprising: a multi-stage evaporator, an outer shell is arranged outside the multi-stage evaporator, and a light collector is arranged below the multi-stage evaporator.

[0009] Further, the multi-stage evaporator comprises a bottommost heat disc, a plurality of evaporation discs are arranged directly above the heat disc, and the inner wall of the outer shell is not in contact with the edge of the evaporation disc.

[0010] Further, the outer shell is conical, and the heat disc and the evaporation disc in the multi-stage evaporator are conical.

[0011] Further, the conical top angle of the heat disc and the evaporation disc is 30-75°.

[0012] Further, the thickness of the heat disc and the evaporation disc is 0.1-1 mm, and the distance between the heat disc and the evaporation disc and between each evaporation disc is 5-30 mm.

[0013] Further, the upper surface of the heat disc and the evaporation disc is provided with an evaporation disc; the bottom of the heat disc is provided with a light-heat conversion coating with a thickness of 0.2-0.3 mm.

[0014] Further, the top end of the heat disc and the evaporation disc is provided with a hole, and the opening diameter of the hole is 5-10% of the radius of the cone of the evaporation disc.

[0015] Further, the top of the outer side of the heat disc and the evaporation disc is provided with a baffle, and a sealing drainage cloth is arranged at the bottom of the outer side of each evaporation disc; the upper part of each baffle is in contact with the bottom of the sealing drainage cloth.

[0016] Further, the edge position of the heat disc and the evaporation disc is further provided with a drainage outlet, the position of the drainage outlet is inside in the vertical direction of the baffle, the setting density of the drainage outlet is controlled to be 3-10 cm, the hole diameter of the drainage outlet is 3-10 mm, and the length of the tubular part extended at the lower part of the drainage outlet is 3-10 mm and does not contact the lower layer.

[0017] Further, the outermost part inside the bottom of the outer shell is provided with a water collecting tank. Beneficial effects

[0018] The beneficial effects of the embodiments of the present application are:

[0019] 1. The water production efficiency of the multi-stage solar distiller is improved, and the water production energy efficiency can reach 6.2 L / kWh under the input power of 1 kW m -2 The energy utilization rate is increased, and 4 kW m-2 The above energy input power can still effectively condense steam to obtain fresh water, and the energy efficiency does not decrease obviously. The water production of the multi-stage solar distiller per unit area is promoted, and the water production per square meter of the net water device can reach 30 L / h at an energy input power of 6 kW m -2 The water production per square meter of the net water device can reach 30 L / h at an energy input power of 6 kW m -2 The energy input power of the net water device can reach 30 L / h at an energy input power of 6 kW m

[0020] 2, The inverted solar multi-stage evaporation water purifier can also meet the solar water production demand in low irradiation areas and rainy areas, and can work at an energy input power of 0.4 kW m -2 The energy input power of the net water device can reach 30 L / h at an energy input power of 6 kW m

[0021] 3, The waste water produced by the inverted solar multi-stage evaporation water purifier can be higher than 20%, and the concentrated waste water can be continuously discharged to prevent salt accumulation. The dissolved salt and other impurities can be continuously removed, and the evaporation plate does not need to be cleaned frequently.

[0022] 4, The evaporation plates of the inverted solar multi-stage evaporation water purifier are stacked from bottom to top, and the outer shell is used to reduce steam loss and increase condensate water. The evaporation surface of the internal multi-stage evaporation plate is upward, which improves the evaporation rate and greatly improves the overall evaporation efficiency.

[0023] 5, Because the evaporation efficiency is improved, it is possible to input more heat power, and a focusing type reflecting condenser can be used. The solar energy is supplied from the bottom of the inverted solar multi-stage evaporation water purifier, and the energy density per unit area can be 1 kW m -2The power of the inverted solar multi-stage evaporation water purifier is 4-6 times that of the conventional solar water purifier, and the repeated use of the latent heat of steam greatly improves the energy-fresh water efficiency of the inverted solar multi-stage evaporation water purifier, improves the utilization rate of the inverted solar multi-stage evaporation water purifier per unit area, and the cost of the light collector per unit area is much cheaper than that of the multi-stage evaporator, so the equipment cost is greatly reduced, which is only about 1 / 5 of the cost of the device without a light collector.

[0024] 6, the raw water flows from top to bottom, only needs to be naturally realized under gravity, without other energy consumption to drive, and only the concentrated wastewater flows out from the bottom, the raw water is heated and evaporated multiple times, the energy utilization rate is high. The liquid flows more naturally, making the water supply efficiency high, ensuring that the inverted solar multi-stage evaporation water purifier can run under high power input conditions.

[0025] 7, the salt-containing water can continuously flow out of the evaporation tray from top to bottom, and finally flow out of the device, continuously taking away the salt, which will not stagnate and precipitate, ensuring that the device can continuously and stably run under high power energy input conditions. At the same time, the wastewater only flows out of the device from the bottom layer, the heat is maximized in the evaporation layer, which is beneficial to the efficient use of energy. Compared with the known cavity structure design (Passive solar desalination towards high efficiency and salt rejection via a reverse-evaporating water layer of millimetre-scale thickness. Nat Water, 2023, 1, 790-799. As shown in Figure 3 in the literature), which needs to take the way of separately leading out the concentrated salt water from each layer, the device not only has an extremely simple structure, but also consumes about 5-8% less energy.

[0026] 8, the capital cost of the inverted solar multi-stage evaporation water purifier of the present application is about 140 yuan RMB, which is lower than the capital cost of 170 yuan RMB recommended by the World Bank for obtaining tap water in remote areas, and has strong competitiveness and generalizability. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0028] Figure 1 is a structural schematic diagram of an embodiment of the present application.

[0029] Figure 2 is a structural diagram of a multi-stage evaporator in an embodiment of the present application.

[0030] Figure 3 is a structural diagram of a baffle position in an embodiment of the present application.

[0031] Figure 4 is a diagram of the overall flow cycle of raw water, steam and purified water in an embodiment of the present application.

[0032] Figure 5 is a diagram of the specific flow of raw water in an embodiment of the present application.

[0033] Figure 6 is a diagram of the specific flow of steam and purified water in an embodiment of the present application.

[0034] Figure 7 is a diagram of ion concentration of seawater before treatment by a water purifier in an embodiment of the present application.

[0035] Figure 8 is a diagram of ion concentration of seawater after treatment by a water purifier in an embodiment of the present application.

[0036] Figure 9 is a diagram of the flow of raw water and purified water at an evaporation tray in an embodiment of the present application.

[0037] Figure 10 is a diagram of the design principle of the angle of an evaporation tray in an embodiment of the present application. Wherein, a is the distribution of the molar ratio of salt to water on the evaporation tray after evaporation of surface water for a certain period of time (different colors represent different molar ratios of salt, and the color scale is shown on the left); b is the distribution of the molar ratio of salt to water on the evaporation tray at different horizontal angles after evaporation of surface water for a certain period of time (different colors represent different molar ratios of salt, and the color scale is shown on the left); c is the change of the total molar ratio of salt to water in the evaporation tray over time after evaporation of surface water for a certain period of time; d is the change of the molar ratio of salt to water on the surface of the evaporation tray over time after evaporation of surface water for a certain period of time.

[0038] Figure 11 is a diagram of the state of the evaporation tray of a conventional multi-stage evaporator after continuous operation for 3.5 hours.

[0039] Figure 12 is a photograph of the evaporation tray of an embodiment of the present application after continuous operation for 200 hours without salt accumulation when the angle between the evaporation tray and the horizontal plane is 30 degrees.

[0040] Figure 13 is a diagram of the conductivity of the purified water produced by an embodiment of the present application after continuous operation for 200 hours.

[0041] In the figure, 1-1 is an outer shell, 1-2 is a multi-stage evaporator, 1-3 is a raw water pool, 1-4 is a water collection tank, 1-5 is a waste water drainage pipe, 1-6 is a condenser, 1-7 is a baffle, 1-8 is a water outlet, 1-9 is a hole, 1-10 is a sealing drainage cloth, 1-2-1 is a heating tray, and 1-2-2 is an evaporation tray. Best Mode for Carrying Out the Invention

[0042] With reference to the drawings and embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0043] The embodiment of the present application provides an inverted solar multistage evaporation water purifier, and the structure is shown in Fig. 1.

[0044] The multistage evaporator 1-2 is externally provided with a shell 1-1, the shell 1-1 is conical, the top is thin and the bottom is wide; the top of the multistage evaporator 1-2 is connected with the raw water pool 1-3 through a pipeline at the opening, and the bottom of the multistage evaporator 1-2 is provided with a condenser 1-6.

[0045] Further, the shell 1-1 is used for preventing steam leakage and reducing heat loss, the shell 1-1 is made of plastic and is externally provided with foam for heat preservation. The inner wall of the shell 1-1 is not in contact with the edge of the evaporation disc 1-2-2, and a distance of 1-10 mm is left.

[0046] The condenser 1-6 can be a 6-10 times focusing condenser.

[0047] The structure of the multistage evaporator 1-2 is shown in Fig. 2: the multistage evaporator 1-2 comprises a heating disc 1-2-1 at the bottom, a plurality of evaporation discs 1-2-2 are arranged directly above the heating disc 1-2-1, and the heating disc 1-2-1 and the evaporation disc 1-2-2 are both conical.

[0048] The conical top angle of the heating disc 1-2-1 and the evaporation disc 1-2-2 is 30-75°. As shown in Fig. 10. If the conical top angle is higher than 75° (i.e. the conical surface is more horizontal), the salt on the evaporation disc 1-2-2 will be accumulated and precipitated; when the conical top angle is lower than 30°, the capillary action of the evaporation disc is not enough to effectively transport the low-concentration salt water, and the top is easy to be evaporated dry, resulting in salt accumulation. The setting of the parameters is found through many experiments.

[0049] The thickness of the heating disc 1-2-1 and the evaporation disc 1-2-2 is 0.1-1 mm.

[0050] The distance between the heating disc 1-2-1 and the evaporation disc 1-2-2 and the distance between the evaporation discs 1-2-2 are 5-30 mm.

[0051] Preferably, the number of layers of the evaporation disc 1-2-2 is 20.

[0052] Optionally, the heating disc 1-2-1 and the evaporation disc 1-2-2 are made of metal, preferably aluminum; the area of the heating disc 1-2-1 and the evaporation disc 1-2-2 is 600 cm 2 The heating disc 1-2-1 and the evaporation disc 1-2-2 cannot be made of plastic, because the strength of plastic is not enough, and when the strength is enough, the thickness is too thick, which will cause the heat transfer to deteriorate.

[0053] The upper surface of the heating disc 1-2-1 and the evaporation disc 1-2-2 is provided with an evaporation cloth, so the upper surface of the evaporation disc 1-2-2 serves as the evaporation surface. The evaporation cloth is a commercially available hydrophilic cloth, preferably a porous and loose cotton cloth and hemp, with a thickness of 1-2 mm.

[0054] The bottom of the heating disc 1-2-1 is provided with a light-heat conversion coating, which can absorb light and convert it into heat to evaporate the moisture on the upper surface. The light-heat conversion coating is obtained by brushing and drying a commercially available solar light-heat coating. The composition of the coating is a mixture of copper oxide, manganese dioxide, cobalt oxide, chromium oxide, iron oxide, lead sulfide, nickel sulfide and other microparticles with light absorption capacity in polyacrylic resin. The light-heat conversion rate of the coating reaches 90-95%, and the coating is brushed 3-5 times to make the coating film thickness reach 0.2-0.3 mm, ensuring the light absorption degree and heat transfer efficiency under high radiation conditions.

[0055] The working temperature range of the heating disc 1-2-1 is between 30-100℃.

[0056] Further, the top of the heating disc 1-2-1 and the evaporation disc 1-2-2 is provided with a hole 1-9. The hole 1-9 allows non-condensable water vapor to be transported upward as soon as possible, avoiding stagnation in the layer. On the one hand, it avoids inhibiting the evaporation of water on the evaporation cloth of the layer, and on the other hand, it can reduce the temperature difference between the layers to 1-2℃. The opening diameter of the hole 1-9 is 5-10% of the radius of the evaporation cloth, too large opening diameter reduces the evaporation area, and the heat exchange is not sufficient, too small opening diameter is not suitable for steam transmission, which limits the evaporation speed.

[0057] As shown in Figure 3, a baffle 1-7 is provided on the top of the heating disc 1-2-1 and the evaporation disc 1-2-2 outside, and a sealing drainage cloth 1-10 is provided on the bottom of each evaporation disc 1-2-2 outside; the upper part of each baffle 1-7 and the bottom of the sealing drainage cloth 1-10 are in contact.

[0058] As an example, the evaporation disc 1-2-2 is provided with a baffle 1-7 at a distance of 1 cm from the bottom, to prevent raw water from flowing to the bottom edge, and the raw water can flow smoothly to the next layer from the drainage outlet 1-8.

[0059] The baffle 1-7 plays a role of supporting the heating disc 1-2-1 and the evaporation disc 1-2-2, and also plays a role of preventing the raw water from flowing to the bottom edge to mix with the condensed water, so that the raw water can flow to the next layer smoothly through the water outlet.

[0060] The water outlet 1-8 is arranged at the edge position of the heating disc 1-2-1 and the evaporation disc 1-2-2, so that the salt water can flow out through the water outlet. The position of the water outlet 1-8 is inside in the vertical direction of the baffle 1-7. The setting density of the water outlet is controlled to be 3-10 cm. If the density is less than 3 cm, the water cannot be absorbed by the evaporation in time. If the density is greater than 10 cm, the water flows downward too slowly to follow the evaporation rate under the condition of high power. The water outlet is preferably 3-10 mm in diameter. If the diameter is less than 3 mm, the water flows downward too slowly. If the diameter is greater than 10 mm, it is not conducive to effectively utilizing the area of the evaporation disc 1-2-2 for evaporation. The tubular part of the water outlet extends downward by 3-10 mm without contacting the lower layer, which can be assembled as appropriate. If the length is less than 3 mm, the condensed fresh water will be contaminated. If the length is too long, it cannot be tightly assembled.

[0061] The material of the sealing drainage cloth is selected to be water-absorbing paper which is not easy to compress and deform. By using the water-absorbing paper, the liquid water transport performance of the water-absorbing paper at the bottom layer can remain unchanged under the condition of building 30 layers of evaporation discs 1-2-2. The sealing drainage cloth can be tightly combined with the lower surface of the baffle 1-7, effectively preventing the evaporation disc 1-2-2 from leaking steam from the bottom, causing the problem that the steam cannot circulate in the multi-stage evaporator 1-2, and achieving the effect of fully utilizing the latent heat.

[0062] In the traditional upright structure, heat is transferred from top to bottom, and heat transfer is achieved by heat conduction. In order to achieve efficient heat transfer, the spacing between evaporation layers needs to be small enough. Generally, the heat transfer efficiency decreases significantly when the spacing exceeds 10 mm, which makes the boiling of high-power input pollute the fresh water.

[0063] Compared with the upright structure, the steam is transmitted upward in the present application, which is a natural convection process. The heat transfer efficiency is higher than that of heat conduction. Therefore, the change in distance does not decrease but increases the heat transfer efficiency, thereby allowing the spacing between the evaporation discs 1-2-2 to be expanded to 3 cm without significant decrease in heat transfer efficiency, greatly reducing the possibility of pollution of the fresh water. In addition, the mass transfer process of upward evaporation is more efficient, allowing for greater energy input power.

[0064] The outermost part of the bottom of the outer shell 1-1 is provided with a water collecting tank 1-4. The fresh water collected in the water collecting tank 1-4 is discharged through an external pipeline.

[0065] The concentrated waste water flowing out of the water outlet 1-8 is discharged through the waste water drainage pipe 1-5. Embodiment of the present application

[0066] The working process of the inverted solar multistage evaporation water purifier is shown in FIGS. 4-6 and 9, and specifically includes:

[0067] Sunlight is reflected to the bottom of the multistage evaporator 1-2 by the condenser 1-6, the heating disc 1-2-1 generates heat and transfers the heat to the upper surface of the evaporation disc, and the water absorbed and distributed on the upper surface of the evaporation disc evaporates; the water vapor reaches the evaporation disc 1-2-2, is condensed on the lower surface to form water droplets, flows down the lower surface to the sealed drainage cloth 1-10, and then reaches the bottom edge of the evaporation disc 1-2-2 through the pores in the sealed drainage cloth 1-10, and is collected and flows out freely. The latent heat released by the condensation of the water vapor is released, and the evaporation disc 1-2-2 is heated; when the evaporation disc 1-2-2 is heated, the evaporation disc 1-2-2 is paved with the evaporation disc, and the water can flow to the next layer under the action of gravity, and then the water in the next layer flows upward by capillary action of the evaporation disc, and is uniformly distributed on the upper surface of the evaporation disc 1-2-2; as the water evaporates, the salinity of the water increases, and the density increases, which is higher than the density of the water entering the bottom of the evaporation disc 1-2-2, so that convection occurs, so that the high-concentration salt water flows downward, and the raw water continuously moves upward, avoiding the crystallization and precipitation of the salt.

[0068] The water vapor is condensed on the lower surface of the evaporation disc 1-2-2 to form condensed water, and the raw water can flow downward layer by layer, but the purified water does not directly contact the raw water, avoiding secondary pollution, so that the separation and removal of the salt in the water are realized, and the condensed water is obtained as purified water. The salt in the raw water is rarely evaporated into water vapor. The salt water can continuously flow out of the evaporation disc 1-2-2 from top to bottom, and finally flow out of the device, continuously taking away the salt, so that the salt does not stay and precipitate, ensuring that the device can continuously and stably operate under high-power energy input conditions. The waste water only flows out of the device from the lowest layer, and the heat is maximally maintained in the evaporation layer, which is beneficial to the efficient use of energy.

[0069] The steam flows from bottom to top, and the part not completely condensed is cooled by the shell 1-1; the purified fresh water is collected through the bottom water collecting tank 1-4, and flows out through the water outlet. During the working process, the heat of the waste water and the distilled water flowing out can be recovered by the raw water through the external heat exchanger, so that the inlet water is preheated to increase the temperature when entering the evaporator. Embodiment

[0070] The inverted solar multistage evaporation water purifier of the embodiment of the present application works under the sun, and when the radiation power is about 1000 W m -2 , the water production of the water purifier can reach 30 L h -1 m -2 , and the daily water production exceeds 100 L m -2When sea water is used as raw water, the conductivity of the purified water is only 20-30 μS cm -1 , far below the requirement of drinking water. Further analysis of the purified water shows that the main salt ions are effectively removed, as shown in Figures 7-8: the concentrations of sodium, potassium and magnesium ions are all reduced to below 10 ppm, which is more than 2000 times of the raw sea water, and the concentration of calcium ions is also below 140 ppm, meeting the requirement of the national standard GB5749-2006. Technical and economic analysis of the device shows that the capital cost of the embodiment of the present application is about 140 RMB.

[0071] Figure 12 is a photo of the embodiment of the present application, showing that no salt accumulation occurs after 200 hours of continuous work at an angle of 30 degrees between the evaporation and the horizontal plane, which confirms that the working efficiency is not affected.

[0072] Figure 13 is a graph showing that the conductivity of the purified water produced by the embodiment of the present application is far below the drinking water standard after 200 hours of continuous work, and no pollution occurs. Embodiment

[0073] The inverted solar multi-stage evaporation water purifier of the embodiment of the present application processes raw water with high hardness, and the calcium hardness is 180 ppm. A commercially available scale inhibitor HT-521 is added to the system at a ratio of 5-200 milligrams of the agent per liter of water, and the concentration of calcium in the obtained waste water is 1.5 g / L. No scaling occurs after 200 hours of continuous operation. The conductivity of the obtained fresh water is 20-30 μS cm -1 . Embodiment

[0074] The heating disc is replaced by a resistance wire heating method, and no condenser is used, and the rest of the structure is the same as that of the embodiment of the present application. When the heating power is 1000 W m -2 , the water production of the water purifier can reach 30 L h -1 m -2 , and the water production in 8 hours exceeds 2400 L m -2 . When sea water is used as raw water, the conductivity of the purified water is only 20-30 μS cm -1 , far below the requirement of drinking water. The device can be used as a supplement when there is lack of sunlight on rainy days. Embodiment

[0075] A condenser 1-6 with 10 times focusing is used, the solar radiation power is 400 W m -2 , and the water inlet speed of the raw water is appropriately reduced. The water production of the water purifier can reach 18 L h -1 m -2 , and the water production in 8 hours exceeds 140 L m -2When seawater is used as the raw water source, the conductivity of the resulting purified water is only 20~30 μS cm⁻¹. -1 This device can be used in applications that address cloudy days, low solar radiation levels, or specific regions. Example

[0076] Using the structure described in this embodiment, the solar radiation power is 400 W / m². -2 At the same time, using a 6x condenser lens, compared with Example 1, the influent flow rate was reduced by 60%, and the per-unit-time water production rate was 14.4 L / h. -1 m -2 Water production in 8 hours: 115 L / m³ -2 It is evident that simply adjusting the multiplier of concentrators 1-6 cannot achieve the same water production as in Example 4. In contrast, the concentrators 1-6 of this device are completely independent of the multi-stage evaporators 1-2, allowing for convenient and appropriate adjustments based on changes in solar radiation at different times to meet specific usage requirements. Example

[0077] A positive-position evaporative water purifier that does not use concentrators 1-6 has a multi-stage evaporation structure with the light-absorbing and heating surface facing upwards and the evaporation surface facing downwards. When the positive-position evaporative water purifier reaches 1000 W / m²... -2 At that time, the water production efficiency reached 4.5 L / h. -1 m -2 Total water production in 8 hours: 36 L / h -1 m -2 At a solar radiation power of 400 W / m -2 During the first three hours, almost no distilled water was produced; after eight hours of heating, distilled water was only produced in the last five hours. The total water production over eight hours was only 8 L / m³. -2 Example 6 produced significantly less water than Example 5, less than 1 / 10. This was because the temperature of the evaporation layer inside the evaporator was too low, the temperature difference between the layers was too large, the latent heat recycling effect was poor, the energy efficiency decreased, and the total water production was severely reduced.

[0078] Furthermore, as shown in Figure 11, salt buildup occurs after 3.5 hours of continuous operation. Industrial applicability

[0079] 1. Improve the water production efficiency of multi-stage solar stills at 1 kW m³ / s. -2 At the given energy input power, the water production efficiency can reach 6.2 L / kWh. Increasing energy utilization can achieve 4 kW m³ / kWh. -2 The above energy input power is still sufficient to effectively condense steam to obtain fresh water, and the energy efficiency has not decreased significantly. This promotes the increase in water production per unit area of ​​multi-stage solar stills, reaching 6 kW / m³. -2The water production per square meter of the water purifier can reach 30 L / h under the energy input power, and the daily water production exceeds 100 L, which is 2.5 times more than the highest daily water production of the current solar distiller. And the concentrated salt wastewater is continuously introduced, the dissolved substances are inhibited from precipitating, and the maintenance cost is reduced. However, in the existing multi-stage evaporation water purification technology, due to the low recycling rate of energy and the insufficient layer spacing caused by limited heat transfer, the water purification is polluted and the salt is aggregated when high-power energy is input, which cannot be continuously operated, or the condensation efficiency cannot keep up with the evaporation speed, resulting in steam leakage, serious loss of latent heat recycling and water production. In addition, in the structure of the existing multi-stage evaporation water purifier, the evaporation layers are completely sealed, so the internal pressure increases with the increase of heating power, which inhibits water evaporation. The embodiment of the present application makes the whole device work at 0~6 kW m -2 Each layer is operated at normal pressure under the energy input power, improving the water evaporation efficiency of all layers.

[0080] 2, The inverted solar multi-stage evaporation water purifier of the embodiment of the present application can also meet the solar water production demand in low irradiation areas and rainy areas, and work at an energy input power of 0.4 kW m -2 The device only needs to use solar energy, without other external energy input and mechanical auxiliary components, with extremely low asset investment, and can meet the high-quality water supply demand in underdeveloped areas, and can be applied industrially.

[0081] 3, The inverted solar multi-stage evaporation water purifier of the embodiment of the present application can produce wastewater with a concentration higher than 20%, and due to the continuous outflow of concentrated wastewater, salt aggregation can be prevented, and dissolved salts and other impurities can be continuously removed, without aggregation and precipitation on the evaporation disc, eliminating the need for frequent cleaning and maintenance.

[0082] 4, The inverted solar multi-stage evaporation water purifier of the embodiment of the present application is stacked from bottom to top, and the outer shell is used to reduce steam loss and increase condensed water. The evaporation surface of the internal multi-stage evaporation disc is upward, which improves the evaporation rate and greatly improves the overall evaporation efficiency.

[0083] 5, Due to the improved evaporation efficiency, it is possible to input more heat power, and a focusing type reflecting mirror can be used to supply solar energy from the bottom of the inverted solar multi-stage evaporation water purifier, and the energy density per unit area can be 1 kW m -2The power of 4-6 times, and the repeated use of steam latent heat greatly improves the energy-fresh water efficiency of the inverted solar multi-stage evaporation water purifier, improves the utilization rate of the inverted solar multi-stage evaporation water purifier per unit area, and the cost of the condenser per unit area is much cheaper than the multi-stage evaporator, so the equipment cost is greatly compressed, and the cost of the device without a condenser is nearly 1 / 5 of the cost of the positive structure.

[0084] 6, the raw water flows from top to bottom, only needs to be naturally realized under gravity, without other energy consumption to drive, and only from the bottom of the concentrated wastewater, raw water is heated and evaporated many times, and the energy utilization rate is high. Liquid flow is more natural, making the water supply efficiency high, ensuring that the inverted solar multi-stage evaporation water purifier can run under high power input conditions.

[0085] 7, the salt-containing water can continuously flow out of the evaporation tray from top to bottom, and finally flow out of the device, continuously taking away the salt, and not stagnating and precipitating, ensuring that the device can continuously and stably run under high power energy input conditions. At the same time, the wastewater only flows out of the device from the bottom layer, and the heat is maximized in the evaporation layer, which is beneficial to the efficient use of energy. Compared with the known cavity structure design (Passive solar desalination towards high efficiency and salt rejection via a reverse-evaporating water layer of millimetre-scale thickness. Nat Water, 2023, 1, 790-799. As shown in Figure 3 in the literature), it is necessary to take the way of separately leading out the concentrated salt water from each layer, and the device not only has an extremely simple structure, but also consumes about 5-8% less energy.

[0086] 8, the inverted solar multi-stage evaporation water purifier of the present application, through technical and economic calculation, the capital cost of the embodiment of the present application is about 140 yuan, which is lower than the capital cost of 170 yuan recommended by the World Bank for obtaining tap water in remote areas, and has strong competitiveness and generalizability.

[0087] Therefore, it has industrial applicability.

Claims

1. An inverted solar multi-stage evaporation water purifier comprising: Multi-stage evaporator (1-2), the outer shell (1-1) is arranged outside the multi-stage evaporator (1-2), characterized by, the opening at the top of the multi-stage evaporator (1-2) is connected with the raw water pool (1-3) through the pipeline, and the light collector (1-6) is arranged below the multi-stage evaporator (1-2).

2. The inverted solar multistage evaporation water purifier according to claim 1, characterized in that, The multi-stage evaporator (1-2) comprises the bottommost heat disc (1-2-1), and a plurality of evaporation discs (1-2-2) are arranged directly above the heat disc (1-2-1), and the inner wall of the shell (1-1) is not in contact with the edge of the evaporation disc (1-2-2).

3. The inverted solar multistage evaporation water purifier according to claim 1, characterized in that, The shell (1-1) is conical, and the heat disc (1-2-1) and the evaporation disc (1-2-2) in the multi-stage evaporator (1-2) are conical.

4. The inverted solar multistage evaporation water purifier according to claim 3, characterized in that, The conical top angle of the heat disc (1-2-1) and the evaporation disc (1-2-2) is 30-75°.

5. The inverted solar multistage evaporation water purifier according to claim 2 or 3, characterized in that, The thickness of the heat disc (1-2-1) and the evaporation disc (1-2-2) is 0.1-1 mm, and the distance between the heat disc (1-2-1) and the evaporation disc (1-2-2) and between each evaporation disc (1-2-2) is 5-30 mm.

6. The inverted solar multistage evaporation water purifier according to claim 2, characterized in that, The upper surface of the heat disc (1-2-1) and the evaporation disc (1-2-2) is provided with an evaporation disc; the bottom of the heat disc (1-2-1) is provided with a light-heat conversion coating, and the thickness is 0.2-0.3 mm.

7. The inverted solar multistage evaporation water purifier according to claim 2, characterized in that, The top of the heat disc (1-2-1) and the evaporation disc (1-2-2) is provided with a hole (1-9), and the opening diameter of the hole (1-9) is 5-10% of the cone radius of the evaporation disc.

8. The inverted solar multistage evaporation water purifier according to claim 2, characterized in that, The top of the heat disc (1-2-1) and the evaporation disc (1-2-2) is provided with a baffle (1-7), and the bottom of each evaporation disc (1-2-2) is provided with a sealing drainage cloth (1-10); the upper part of each baffle (1-7) is in contact with the bottom of the sealing drainage cloth (1-10).

9. The inverted solar multistage evaporation water purifier according to claim 2, characterized in that, The edge position of the heat disc (1-2-1) and the evaporation disc (1-2-2) is also provided with a drainage outlet (1-8), and the position of the drainage outlet (1-8) is inside in the vertical direction of the baffle (1-7), the setting density of the drainage outlet (1-8) is controlled to be 3-10 cm, the hole diameter of the drainage outlet (1-8) is 3-10 mm, and the tubular part of the lower part of the drainage outlet (1-8) extends for 3-10 mm and does not contact the lower layer.

10. The inverted solar multistage evaporation water purifier according to claim 1, characterized in that, The outermost part in the bottom of the shell (1-1) is provided with a water collecting tank (1-4).

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