A solar seawater desalination and refined salt extraction device

Abstract

The present invention discloses a solar seawater desalination and refined salt extraction device, which includes a light-transmitting and heat-insulating layer, a heat-insulating gap, a photo-thermal layer, a heat conductor, and a brine concentrator and a crude salt extractor arranged in parallel below the heat conductor layer, which are tightly stacked from top to bottom. The brine concentrator includes three parts composed of the same water and salt transportation line: an evaporation layer, a brine supply line, and a concentrated brine reflux line, a condensation collection tank, and a brine tank. The crude salt extractor includes three parts composed of the same water and salt transportation line: an evaporation layer, a brine supply line, and a salt extraction line, a condensation collection tank, a brine tank, a refined salt collection box, and a waste liquid tank. The concentrated brine generated by the brine concentrator is used to wash the crude salt solid generated by the crude salt extractor to obtain refined salt. In one device, the present invention can separate water and refined salt from seawater only by using solar energy, and is applicable to fields such as seawater / salt lake desalination and refined salt extraction.

Description

Technical Field

[0001] The present invention belongs to the field of solar seawater desalination and refined salt extraction, and particularly relates to a solar seawater desalination and refined salt extraction device. Background Art

[0002] At present, seawater desalination and refined salt extraction are two different industrial categories, which are realized by using different technical routes and equipment respectively. The technical routes of seawater desalination mainly have two categories: one is the heat-driven evaporation technology, such as low-temperature multi-effect evaporation, etc.; the other is the pressure-driven membrane desalination technology, such as reverse osmosis membrane, etc. The technical routes of seawater refined salt extraction mainly have two categories: one is to remove other ions such as magnesium and calcium by precipitation method; the other is natural solar salt production, and the obtained concentrated brine is used to treat crude salt to extract refined salt. Seawater desalination technology requires a large amount of high-grade heat energy or electric energy, generates a large amount of carbon emissions, and the distribution location highly depends on large-scale energy facilities. The efficiency of seawater refined salt extraction technology is low and the pollution is large. These technologies are restricted by factors such as energy consumption and environmental protection, and no longer meet the requirements of the new situation.

[0003] In recent years, a completely new solar photothermal interfacial evaporation seawater desalination technology has become a research hotspot in the field of seawater desalination due to its evaporation rate several times that of natural evaporation and solar energy conversion efficiency. This interfacial evaporation technology does not need to heat a large amount of water body as a whole, but only needs to heat a small amount of water on the surface layer, which greatly improves the evaporation rate and solar thermal efficiency. Generally, existing various solar interfacial evaporators adopt anti-salt design to maintain stable seawater desalination performance, that is, by optimizing the design to make salt ions passively diffuse and reflux, which can avoid salt precipitation blocking the equipment, but at the same time produce concentrated brine. Further, by designing to guide salt ions to precipitate away from the evaporation surface, crude salt extraction can be realized. However, there is no technical solution for refined salt extraction based on this photothermal interfacial evaporation technology, and it is still a major challenge to simultaneously realize seawater desalination and refined salt extraction in one device. Summary of the Invention

[0004] The purpose of the present invention is to provide a solar seawater desalination and refined salt extraction device, which uses solar energy to synchronously separate water and salt in salt water to obtain pure water and extract refined salt solid.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] It includes a light-transmitting heat-insulating layer, a heat-insulating gap, a photothermal layer, a heat-conducting layer which are closely stacked from top to bottom, and a brine concentrator and a crude salt extractor arranged side by side below the heat-conducting layer;

[0007] The brine concentrator includes a first evaporation layer, a first brine supply line, and a concentrated brine return line composed of the same water-salt transport line. The upper surface of the first evaporation layer is closely attached to the heat conduction layer, and a first condensation collection tank and a first brine tank are closely stacked from top to bottom at the lower end of the first evaporation layer. The bottom ends of the first brine supply line and the concentrated brine return line are inserted into the first brine tank; the first evaporation layer is a trapezoidal structure, and the ratio of the line segment lengths at the intersection of the first brine supply line and the first evaporation layer and at the intersection of the first evaporation layer and the concentrated brine return line is (2:1) to (5:1);

[0008] The crude salt extractor includes a second evaporation layer, a second brine supply line, and a salt extraction line composed of the same water-salt transport line. The upper surface of the second evaporation layer is closely attached to the heat conduction layer, and a second condensation collection tank and a second brine tank are closely stacked from top to bottom at the lower end of the second evaporation layer. The bottom end of the second brine supply line is inserted into the second brine tank. A refined salt collection box for receiving the crude salt solid that falls from the salt extraction line is provided at the lower end of the salt extraction line, and the salt extraction line is a trapezoidal structure with the ratio of the upper and lower base side lengths being (1:2) to (1:5). A strainer and a concentrated brine conduit connected to the first brine tank are provided in the refined salt collection box, and a waste liquid tank is further installed at the lower end of the refined salt collection box.

[0009] The light-transmitting heat-insulating layer is made of glass or plastic with a high full-spectrum transmittance; the heat-insulating gap is vacuum or filled with air.

[0010] The photo-thermal layer is a material with photo-thermal conversion performance.

[0011] The heat conduction layer is a material with high thermal conductivity and resistance to brine corrosion.

[0012] The water-salt transport line is a hydrophilic fiber cloth.

[0013] The cross-sectional shapes of the first and second condensation collection tanks and the first and second brine tanks are the same as the cross-sectional shapes of the first and second evaporation layers.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. Existing seawater desalination and refined salt extraction are two different industries, and their respective functions are realized through different devices. The present invention combines the two ingeniously, constructs a brine concentrator and a crude salt extractor in a solar evaporator, promotes water evaporation, crude salt extraction, and concentrated brine generation, and finally achieves refined salt extraction. By condensing and collecting steam, fresh water and refined salt solids can be obtained simultaneously in one device. The present invention can separate water and salt from seawater using only solar energy, obtain pure water and refined salt, and is applicable to fields such as seawater desalination / salt extraction, salt lake desalination / salt extraction, etc., effectively improving the universality and economy of the device.

[0016] 2. Existing various solar interface evaporators generally adopt natural upward evaporation of steam and are equipped with a light-transmitting condensation top cover as a condensation collector. However, they face two major problems: a large amount of sunlight is scattered by the water mist on the top cover, and the condensation efficiency of the top cover is low due to being heated by sunlight. Through special design, the present invention enables the steam to evaporate in the reverse direction and condense and collect below, and can also use a large amount of brine for refrigeration to strengthen condensation, successfully avoiding the two major problems of upward evaporation of steam and improving the solar energy conversion efficiency. Description of the Drawings

[0017] Figure 1 is a solar seawater desalination and refined salt extraction device;

[0018] Wherein: 1 - light-transmitting heat-insulating layer, 2 - heat-insulating gap, 3 - photo-thermal layer, 4 - heat-conducting layer, I - brine concentrator: 51 - first evaporation layer, 52 - first brine supply line, 53 - concentrated brine reflux line, 61 - first condensation collection tank, 71 - first brine tank; II - crude salt extractor: 54 - second evaporation layer, 55 - second brine supply line, 56 - salt extraction line, 62 - second condensation collection tank, 72 - second brine tank, 8 - refined salt collection box, 9 - waste liquid tank. Detailed Embodiment

[0019] The present invention will be further described in detail below in conjunction with specific embodiments.

[0020] See Figure 1 , the present invention includes a light-transmitting heat-insulating layer 1, a heat-insulating gap 2, a photo-thermal layer 3, a heat-conducting layer 4 closely stacked from top to bottom, and a brine concentrator I and a crude salt extractor II arranged side by side below the heat-conducting layer 4;

[0021] Among them, the material of the light-transmitting heat-insulating layer 1 is glass or plastic with high full-spectrum transmittance; the heat-insulating gap 2 is vacuum or filled with air;

[0022] The photo-thermal layer 3 is a material with photo-thermal conversion performance. The heat-conducting layer 4 is a material with high thermal conductivity and corrosion resistance to brine. The photo-thermal layer 3 covers the heat-conducting layer 4, converts solar energy into heat, and conducts heat to the evaporation layer below through the heat-conducting layer 4;

[0023] The brine concentrator I includes a first evaporation layer 51, a first brine supply line 52, and a concentrated brine reflux line 53, which are composed of the same water and salt transport lines made of hydrophilic fiber cloth. The upper surface of the first evaporation layer 51 is closely attached to the heat conduction layer 4. At the lower end of the first evaporation layer 51, a first condensation collection tank 61 and a first brine tank 71 are closely stacked from top to bottom. The bottom ends of the first brine supply line 52 and the concentrated brine reflux line 53 are inserted into the first brine tank 71. The first evaporation layer 51 is in a trapezoidal structure. The ratio of the line segment lengths at the junction of the first brine supply line 52 and the first evaporation layer 51 and at the junction of the first evaporation layer 51 and the concentrated brine reflux line 53 is (2:1) to (5:1). The decreasing cross-sectional area outward can generate a unidirectional liquid flow driving force from the first brine supply line 52 to the concentrated brine reflux line 53, promoting the reflux of salt ions into the first brine tank 71. The first evaporation layer 51 receives heat from the heat conduction layer 4 to evaporate steam downward to the first condensation collection tank 61, where it condenses into pure water. At the same time, the concentration of the brine in the first brine tank 71 continuously increases and becomes concentrated brine.

[0024] The crude salt extractor II includes a second evaporation layer 54, a second brine supply line 55, and a salt extraction line 56, which are composed of the same water and salt transport lines. The upper surface of the second evaporation layer 54 is closely attached to the heat conduction layer 4. At the lower end of the second evaporation layer 51, a second condensation collection tank 62 and a second brine tank 72 are closely stacked from top to bottom. The bottom end of the second brine supply line 55 is inserted into the second brine tank 72. At the lower end of the salt extraction line 56, a refined salt collection box 8 is provided for receiving the crude salt solids falling from the salt extraction line 56. The salt extraction line 56 is in a trapezoidal structure, and the ratio of the lengths of the upper and lower bases is (1:2) to (1:5). The decreasing cross-sectional area outward can strengthen the unidirectional flow of brine, causing the increasingly concentrated brine to saturate and precipitate here to obtain crude salt solids and saturated brine. The refined salt collection box 8 is equipped with a strainer 81 and a concentrated brine conduit 82 connected to the first brine tank 71. It simultaneously receives the crude salt solids falling from the salt extraction line 56 and the concentrated brine introduced from the first brine tank 71 through the concentrated brine conduit 82. The concentrated brine flushes the crude salt solids. A waste liquid tank 9 is also installed at the lower end of the refined salt collection box 8 to dissolve and carry the salts other than sodium chloride to the waste liquid tank 9, leaving refined salt on the strainer 81.

[0025] The cross-sectional shapes of the first and second condensation collection tanks 61, 62 and the first and second brine tanks 71, 72 of the present invention are the same as the cross-sectional shapes of the first and second evaporation layers 51, 54. The first and second brine tanks 71, 72 are closely attached below the first and second condensation collection tanks 61, 62 to play a role in strengthening condensation. The concentration of the first brine tank 71 remains unchanged, and the concentration of the second brine tank 72 becomes more and more concentrated brine as evaporation progresses.

[0026] The salt extraction line 56 is trapezoidal in structure and does not insert into the second brine tank 72. Due to the low temperature, high concentration, and decreasing cross-sectional area, Marangoni liquid flow is generated, strengthening the flow of brine. Here, saturation precipitation occurs to obtain crude salt solids and saturated brine. The crude salt solids fall onto the strainer 81 in the refined salt collection box 8 along with the saturated brine. The refined salt collection box 8 includes four walls made of a material resistant to brine corrosion, the bottom of the strainer 81, and a concentrated brine conduit 82. The strainer 81 is in the shape of a grid or mesh. The concentrated brine conduit 82 leads the concentrated brine from the first brine tank 71 into the refined salt collection box 8 to wash the crude salt solids therein, leaving refined salt on the strainer 81, and the waste water flows into the waste liquid tank 9.

[0027] The solar seawater desalination and refined salt extraction device manufactured by the present invention can combine the two industries of seawater desalination and refined salt extraction. Only using solar energy, it can separate water and salt from seawater to obtain pure water and refined salt, and is applicable to fields such as seawater desalination / salt extraction, salt lake desalination / salt extraction, etc.

Claims

1. A solar desalination and refined salt extraction device, characterized in that: it includes a light-transmitting and heat-insulating layer (1), a heat-insulating gap (2), a photo-thermal layer (3) made of a material with photo-thermal conversion performance, a heat-conducting layer (4) made of a material with high thermal conductivity and resistant to salt water corrosion, and a brine concentrator (I) and a crude salt extractor (II) arranged side by side below the heat-conducting layer (4) and tightly stacked from top to bottom; the brine concentrator (I) includes a first evaporation layer (51), a first brine supply line (52), and a concentrated brine reflux line (53) composed of the same water-salt transport line. The upper surface of the first evaporation layer (51) is closely attached to the heat-conducting layer (4), and a first condensation collection tank (61) and a first brine tank (71) are tightly stacked from top to bottom at the lower end of the first evaporation layer (51). The bottom ends of the first brine supply line (52) and the concentrated brine reflux line (53) are inserted into the first brine tank (71); the first evaporation layer (51) is a trapezoidal structure, and the ratio of the line segment lengths at the junction of the first brine supply line (52) and the first evaporation layer (51) and at the junction of the first evaporation layer (51) and the concentrated brine reflux line (53) is (2:1) to (5:1); the crude salt extractor (II) includes a second evaporation layer (54), a second brine supply line (55), and a salt extraction line (56) composed of the same water-salt transport line. The upper surface of the second evaporation layer (54) is closely attached to the heat-conducting layer (4), and a second condensation collection tank (62) and a second brine tank (72) are tightly stacked from top to bottom at the lower end of the second evaporation layer (54). The bottom end of the second brine supply line (55) is inserted into the second brine tank (72). A refined salt collection box (8) for receiving the crude salt solids falling from the salt extraction line (56) is provided at the lower end of the salt extraction line (56), and the salt extraction line (56) is a trapezoidal structure with the ratio of the upper and lower base side lengths being (1:2) to (1:5). A sieve (81) and a concentrated brine conduit (82) communicating with the first brine tank (71) are provided in the refined salt collection box (8), and a waste liquid tank (9) is also installed at the lower end of the refined salt collection box (8).

2. The solar desalination and refined salt extraction device according to claim 1, characterized in that: the light-transmitting and heat-insulating layer (1) is made of glass or plastic with high full-spectrum transmittance; the heat-insulating gap (2) is vacuum or filled with air.

3. The solar desalination and refined salt extraction device according to claim 1, characterized in that: the water-salt transport line is a hydrophilic fiber cloth.

4. The solar desalination and refined salt extraction device according to claim 1, characterized in that: the cross-sectional shapes of the first and second condensation collection tanks (61, 62) and the first and second brine tanks (71, 72) are the same as the cross-sectional shapes of the first and second evaporation layers (51, 54).

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