Heat collection pipe type multi-stage solar seawater desalination device

Abstract

The utility model relates to the field of seawater desalination, in particular to a heat collecting pipe type multi-stage solar seawater desalination device which comprises a closed heat collecting pipe system, a saline water tank, a high-salinity wastewater tank and a purified water tank. A multi-stage evaporation unit and a condensation backflow unit are arranged in the heat collecting pipe system, and the heat collecting pipe system specifically comprises a first-stage evaporation layer tightly attached to the inner wall of a heat collecting pipe, a first-stage condensation backflow layer, a second-stage evaporation layer tightly attached to the first-stage condensation backflow layer, a second-stage condensation backflow pipe, a first-stage water supply pipe and a second-stage water supply pipe from outside to inside. A first-stage purified water outlet, a second-stage purified water outlet, a first-stage high-salinity wastewater outlet and a second-stage high-salinity wastewater outlet are formed in the bottom of the heat collecting pipe system. The device can desalinate seawater or saline water only by solar thermal evaporation to obtain drinking-grade purified water, has the characteristics of high solar energy utilization rate, energy conservation, environmental protection and low cost, can be widely used for desalinating seawater, salt lakes, rainwater and the like to prepare drinking water, and is not only suitable for large-scale desalination facilities, but also suitable for small-scale portable fresh water acquisition scenes.

Description

Technical Field

[0001] The present invention relates to the field of seawater desalination, and particularly to a heat pipe type multi-stage solar seawater desalination device. Background Art

[0002] Existing seawater desalination technologies mainly fall into two categories: one is heat-driven evaporation technology, such as low-temperature multi-effect distillation (LT-MED) and multi-stage flash evaporation (MSF); the other is pressure-driven membrane desalination technology, represented by reverse osmosis membranes (RO). These two methods are both mature large-scale and centralized water supply solutions, but are restricted by the following factors: firstly, they require a large amount of high-quality energy such as electric energy and thermal energy, and highly rely on large-scale power and thermal facilities, so the production capacity and distribution locations are limited; secondly, these technologies require frequent replacement of accessories, and the maintenance technical requirements and costs are relatively high. These factors make these seawater desalination technologies generally applicable to large-scale and centralized scenarios, and cannot meet the needs of small-scale or portable scenarios.

[0003] In recent years, a new type of solar local heating technology - solar-driven interfacial evaporation, due to its higher photothermal conversion efficiency and lower cost advantages, has become the most promising next-generation seawater desalination technology. Different from traditional evaporation systems based on overall heating, this interfacial evaporation system can localize solar energy at the air-water interface for heating, so as to reduce heat loss and improve the utilization rate of thermal energy. Since the solar interfacial evaporation device has a simple structure, small occupied space, high energy utilization rate, and low requirements for the operating environment, it determines that it is not only applicable to large-scale and centralized water supply systems, but also suitable for small-scale and portable devices, and has great potential in aspects such as islands, ships, offshore platforms, and field emergency water supply.

[0004] Generally speaking, the structure of solar-driven interfacial evaporation mainly consists of a light absorption layer, a heat insulation layer, and a water delivery layer. Although this evaporation structure is simple, there are also the following obvious problems, which limit the practical application process of this technology: firstly, the light absorption capacity of the planar light absorption type evaporator is insufficient. Under daily sunlight, the temperature of the evaporation surface can reach up to more than 40 degrees Celsius at most, resulting in a relatively low temperature of the generated steam, which is not conducive to condensation, and a large amount of low-temperature steam cannot be liquefied into fresh water; secondly, the water-salt transport of capillary adsorption type water supply, especially the transport capacity of divalent salt ions such as magnesium and calcium, is insufficient, and it is easy to block the water-salt transport channels with salt; thirdly, the upward steam condensation blocks the light absorption and further condensation and liquefaction of the steam on the transparent top cover. Summary of the Invention

[0005] The purpose of the present utility model is to provide a heat pipe type multi-stage solar seawater desalination device with high solar energy utilization rate, energy conservation and environmental protection, and low cost.

[0006] To achieve the above object, the technical solution adopted by the present innovation is as follows: It includes a first-stage heat collecting tube, a second-stage heat collecting tube which are hermetically installed on the water collecting tray from outside to inside, and a second-stage condensation return pipe communicating with the brine tank. A first-stage water supply pipe and a second-stage water supply pipe passing through the water collecting tray and communicating with the brine tank are arranged in the second-stage heat collecting tube. The outlets of the first-stage water supply pipe and the second-stage water supply pipe are in contact with the tops of the first-stage heat collecting tube and the second-stage heat collecting tube. A first-stage evaporation layer and a second-stage evaporation layer formed by salt-resistant hydrophilic fiber cloth are installed on the inner walls of the first-stage heat collecting tube and the second-stage heat collecting tube. The outer wall of the second-stage heat collecting tube forms a first-stage condensation return layer. And a first brine tank and a first water purification tank with a first-stage high-salt wastewater outlet and a first-stage purified water outlet are opened from outside to inside between the first-stage heat collecting tube and the second-stage heat collecting tube. A second brine tank and a second water purification tank with a second-stage high-salt wastewater outlet and a second-stage purified water outlet are opened from outside to inside in the second-stage heat collecting tube. And the first-stage high-salt wastewater outlet, the second-stage high-salt wastewater outlet, the first-stage purified water outlet, and the second-stage purified water outlet are respectively communicated with the high-salt wastewater tank and the purified water tank.

[0007] The first-stage and second-stage heat collecting tubes are closed and adiabatic vacuum purple gold tubes.

[0008] The brine tank is made of corrosion-resistant material that supplies brine to the first-stage water supply pipe and the second-stage water supply pipe and circulates and supplies cooling water to the second-stage condensation return pipe.

[0009] The first-stage water supply pipe, the second-stage water supply pipe, the second-stage condensation return pipe, the high-salt wastewater tank, and the purified water tank are made of corrosion-resistant material.

[0010] The salt-resistant hydrophilic fiber cloth installed on the inner walls of the first-stage heat collecting tube and the second-stage heat collecting tube is coconut shell fiber cloth or bamboo fiber cloth.

[0011] The diameter of the second-stage heat collecting tube is 1 / 4 - 3 / 4 of the diameter of the first-stage heat collecting tube.

[0012] The beneficial effects of the present invention are as follows:

[0013] 1. Compared with the current mainstream thermal and membrane seawater desalination technologies, the present utility model only needs to use solar energy as the sole energy source, getting rid of the dependence on large-scale energy facilities, eliminating the seawater pretreatment process, improving the desalination water quality, making the effluent water quality directly reach the drinking level, and being applicable not only to large-scale and centralized water supply systems but also to miniaturized and portable devices.

[0014] 2. This device adopts a multi-stage evaporation structure, uses the heat released by the liquefaction of the steam in the previous stage as the heat source for evaporation in the next stage, sets a circulating condensate water path as the steam condensation surface, and utilizes solar energy multi-stage to improve the energy utilization efficiency.

[0015] 3. This device uses adiabatic heat collector tubes for solar thermal absorption. The multi-stage evaporation unit and the condensation and reflux unit are all placed inside the tubes. It has a fast heating rate, a slow cooling rate, good heat preservation performance, can generate high-temperature steam, and improves the evaporation rate and condensation efficiency.

[0016] 4. This device adopts active water supply with negative feedback regulation, which can control and adjust the water supply rate in real time according to information such as light intensity and temperature, so as to effectively match the evaporation rate. At the same time, it can effectively carry away the salt ions accumulated on the surface of the evaporation layer, realizing the maximum energy utilization rate and anti-salt fouling ability.

[0017] 5. Compared with the currently commonly reported water storage evaporation scheme, this device adopts path water supply, which makes the brine evenly distributed on the surface of the evaporation layer. Without an insulation layer, it avoids the cooling effect of the water body, reduces the space while increasing the evaporation area, improves the evaporation efficiency, and reduces the requirements for insulation materials.

[0018] 6. This device adopts a tubular shape, which adapts to the full solar light receiving angle, facilitates the uniform distribution of heat on the evaporation surface, and broadens the applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the overall structural schematic diagram of the present utility model;

[0020] Figure 2 is the structural schematic diagram of the water collecting tray 6 of the present utility model;

[0021] In the figure, 1 - first-stage heat collector tube, 2 - second-stage heat collector tube, 3 - high-salt wastewater tank, 4 - clean water tank, 5 - brine tank, 6 - water collecting tray, 11 - first-stage water supply pipe, 12 - first-stage evaporation layer, 13 - first-stage condensation and reflux layer, 14 - first-stage clean water outlet, 15 - first-stage high-salt wastewater outlet, 16 - first clean water tank, 17 - first brine tank, 21 - second-stage water supply pipe, 22 - second-stage evaporation layer, 23 - second-stage condensation and reflux pipe, 24 - second-stage clean water outlet, 25 - second-stage high-salt wastewater outlet, 26 - second clean water tank, 27 - second brine tank. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The structural principle and working principle of the present utility model will be further described in detail below with reference to the drawings.

[0023] See Figure 1, the utility model includes a first-stage heat collecting tube 1, a second-stage heat collecting tube 2 which are hermetically installed on a water collecting tray 6 from outside to inside, and a second-stage condensation return pipe 23 communicating with a brine tank 5. The first and second-stage heat collecting tubes 1 are closed and adiabatic vacuum purple gold tubes, and the diameter of the second-stage heat collecting tube 2 is 1 / 4 - 3 / 4 of the diameter of the first-stage heat collecting tube 1. A first-stage water supply pipe 11 and a second-stage water supply pipe 21 which penetrate through the water collecting tray 6 and communicate with the brine tank 5 are arranged in the second-stage heat collecting tube 2. The outlets of the first-stage water supply pipe 11 and the second-stage water supply pipe 21 are in contact with the tops of the first-stage heat collecting tube 1 and the second-stage heat collecting tube 2. The brine tank 5 is made of corrosion-resistant material and supplies brine to the first-stage water supply pipe 11 and the second-stage water supply pipe 21. The second-stage condensation return pipe 23 bends downward after reaching the top from the brine tank 5 and returns to the brine tank 2 as circulating condensed water. These water supply rates can be automatically adjusted according to sunlight intensity and temperature. A first-stage evaporation layer 12 and a second-stage evaporation layer 22 formed by salt-resistant hydrophilic fiber cloth are installed on the inner walls of the first-stage heat collecting tube 1 and the second-stage heat collecting tube 2. A first-stage condensation return layer 13 is formed on the outer wall of the second-stage heat collecting tube 2. The first-stage water supply pipe 11, the second-stage water supply pipe 21, and the second-stage condensation return pipe 23 are made of corrosion-resistant material tubes. The first-stage water supply pipe 11 and the second-stage water supply pipe 21 directly supply water from the brine tank 5 to the tops of the first-stage evaporation layer 12 and the second-stage evaporation layer 22.

[0024] See Figure 2 , between the first-stage heat collecting tube 1 and the second-stage heat collecting tube 2 of the utility model, a first brine tank 17 and a first water purification tank 16 with a first-stage high-salt wastewater outlet 15 and a first-stage purified water outlet 14 are opened from outside to inside. In the second-stage heat collecting tube 2, a second brine tank 27 and a second water purification tank 26 with a second-stage high-salt wastewater outlet 25 and a second-stage purified water outlet 24 are opened from outside to inside. The first-stage high-salt wastewater outlet 15, the second-stage high-salt wastewater outlet 25, the first-stage purified water outlet 14, and the second-stage purified water outlet 24 communicate with a high-salt wastewater tank 3 and a purified water tank 4 respectively.

[0025] The first-stage water supply pipe 11, the second-stage water supply pipe 21, the second-stage condensation return pipe 23, the high-salt wastewater tank 3, and the purified water tank 4 of the utility model are made of corrosion-resistant material.

[0026] During operation, seawater or brine continuously enters the tops of the first-stage evaporation layer 12 and the second-stage evaporation layer 22 through the first-stage water supply pipe 11 and the second-stage water supply pipe 21 respectively via the brine tank 5, and then wets the entire first-stage evaporation layer 12 and the second-stage evaporation layer 22 under the action of gravity. The first-stage heat collecting pipe 1 generates heat under sunlight irradiation, driving the first-stage evaporation layer 12 and the second-stage evaporation layer 22 to generate steam. Subsequently, after encountering the first-stage condensation and reflux layer 13 and the second-stage condensation and reflux pipe 23 respectively, the steam liquefies and flows downstream to flow out from the first-stage purified water outlet 14 and the second-stage purified water outlet 24 at the bottom, and the purified water is collected and flows into the purified water tank 4. Among them, the steam generated by the first-stage evaporation layer 12 liquefies and releases heat in the first-stage condensation and reflux layer 13, which can drive the second-stage evaporation layer 22 to generate steam. At this time, since the seawater or brine in the brine tank 5 has a relatively low temperature, it can be introduced into the second-stage condensation and reflux pipe 23 as circulating cooling water to enhance the steam condensation effect. After the first-stage evaporation layer 12 and the second-stage evaporation layer 22 generate steam, the remaining high-salinity wastewater flows down to the bottom and flows out from the first-stage high-salinity wastewater outlet 15 and the second-stage high-salinity wastewater outlet 25 into the high-salinity wastewater tank 3.

[0027] Several sets of the devices of the present utility model can be installed on the anti-shake bracket and arranged into a seawater desalination device array, sharing a set of brine tank, high-salinity wastewater tank and purified water tank.

Claims

1. A multi-stage solar seawater desalination device with a heat-collecting tube type, characterized in that: It includes a first-stage heat collection tube (1), a second-stage heat collection tube (2) installed and enclosed on a water collection tray (6) from outside to inside, and a second-stage condensation and reflux pipe (23) communicated with a brine tank (5). A first-stage water supply pipe (11) and a second-stage water supply pipe (21) passing through the water collection tray (6) and communicated with the brine tank (5) are arranged inside the second-stage heat collection tube (2). The outlets of the first-stage water supply pipe (11) and the second-stage water supply pipe (21) are in contact with the tops of the first-stage heat collection tube (1) and the second-stage heat collection tube (2). A first-stage evaporation layer (12) and a second-stage evaporation layer (22) formed by salt-resistant hydrophilic fiber cloth are installed on the inner walls of the first-stage heat collection tube (1) and the second-stage heat collection tube (2). A first-stage condensation and reflux layer (13) is formed on the outer wall of the second-stage heat collection tube (2). A first brine tank (17) with a first-stage high-salt wastewater outlet (15) and a first clean water outlet (14) and a first clean water tank (16) are opened from outside to inside between the first-stage heat collection tube (1) and the second-stage heat collection tube (2). A second brine tank (27) with a second-stage high-salt wastewater outlet (25) and a second clean water outlet (24) and a second clean water tank (26) are opened from outside to inside in the second-stage heat collection tube (2). The first-stage high-salt wastewater outlet (15), the second-stage high-salt wastewater outlet (25), the first-stage clean water outlet (14), and the second-stage clean water outlet (24) are respectively communicated with a high-salt wastewater tank (3) and a clean water tank (4).

2. The multi-stage solar seawater desalination device with a heat collecting tube type according to claim 1, characterized in that: The first-stage and second-stage heat collection tubes (1, 2) are closed and adiabatic vacuum purple gold tubes.

3. The multi-stage solar seawater desalination device with a heat collecting tube type according to claim 1, characterized in that: The brine tank (5) is made of a corrosion-resistant material that supplies brine to the first-stage water supply pipe (11) and the second-stage water supply pipe (21) and circulates and supplies cooling water to the second-stage condensation and reflux pipe (23).

4. The multi-stage solar seawater desalination device with a heat collection tube type according to claim 1, characterized in that: The first-stage water supply pipe (11), the second-stage water supply pipe (21), the second-stage condensation and reflux pipe (23), the high-salt wastewater tank (3), and the clean water tank (4) are made of a corrosion-resistant material.

5. The multi-stage solar seawater desalination device with a heat collecting tube type according to claim 1, characterized in that: The salt-resistant hydrophilic fiber cloth installed on the inner walls of the first-stage heat collection tube (1) and the second-stage heat collection tube (2) is coconut shell fiber cloth or bamboo fiber cloth.

6. The multi-stage solar seawater desalination device with a heat collecting tube type according to claim 1, characterized in that: The diameter of the second-stage heat collection tube (2) is 1 / 4 - 3 / 4 of the diameter of the first-stage heat collection tube (1).

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