ES2938958B2 - Solar energy water condensation and desalination structure for floating desalination systems - Google Patents

Description

DESCRIPTION

Solar energy water condensation and desalination structure for floating desalination systems

TECHNIQUE SECTOR

The present invention falls within the technical sector of water desalination through phase change, particularly desalination through the use of solar energy.

BACKGROUND OF THE INVENTION

The increase in population and climate change has produced an imbalance between the demand and supply of water, both to supply the population and for agriculture and industry. This shortage of drinking water occurs in many areas that have abundant brackish water resources, whether from the sea or from underground wells. The south of Spain and many Mediterranean countries are examples of this type of areas, where the desalination of seawater could solve this problem or at least contribute to its solution, favoring its development and industrial expansion. These areas have good exposure to solar radiation.

Desalination is the process of separating dissolved minerals (salts) and other undesirable substances contained in brackish or marine waters, to convert them into water suitable for human consumption, water suitable for industrial or agricultural use. Among the different most widespread desalination processes currently are the following processes:

-Those that carry out a phase change to obtain water. Among the most notable is the flash distillation process, which is the most used worldwide (especially in the Middle East), although one of its main drawbacks is the high cost it entails both in terms of energy needs and the necessary infrastructures. Another example is the solar distillation process (Solar-Still), which is precisely what constitutes the basis for the system proposed in the present invention.

-Those that operate without phase change and use mechanical energy. Among the most prominent and implemented processes is reverse osmosis. With very expensive installations, this process uses very sensitive, expensive membranes and a large amount of electrical energy for its operation, and it also generates brine.

Likewise, and related to the topic, it is worth mentioning the inventions that are the subject of patents ES2401516 B1, ES2338205 B1 and ES2355022 B1. All of these patents refer to the desalination of water according to the same principle as the present invention, although they differ in the method of obtaining and exploiting the resulting desalinated water. The present invention, compared to ES2401516 B1, which is the one that most closely resembles the system described in this document, uses vacuum tubes (heat pipe system) and not micronebulizers, increasing the temperature gradient and avoiding the gas cloud that prevents the passage of the sun's rays to carry out the correct heat transfer with the water to be desalinated.

EXPLANATION OF THE INVENTION

The present invention is based on the use of renewable energy sources and the improvement in terms of saline waste produced, since these are zero (the process does not generate brine).

A first object of the present invention is a water condensation and desalination structure using solar energy for floating desalination systems.

In an embodiment of the first object of the invention, the water condensation and desalination structure has a geometry essentially of a cone or inverted pyramid whose upper part opens, extrudes or projects outwards. In a preferred embodiment, said structure is made of a material with high mechanical and thermal resistance, low thermal conductivity and low coefficient of thermal expansion, so that it behaves like a cold body.

In an embodiment of the first object of the invention, the solar collectors included in the water condensation and desalination structure are arranged inclined and radially on the internal wall of its geometry to maximize the collection of solar radiation. In a preferred embodiment, the evaporator elements are located or connected at the lower ends of the solar collectors, the “lower end” being understood as that end that is oriented towards the center or interior of the structure.

In an embodiment of the first object of the invention, the lower part of the geometry of the water condensation and desalination structure is entirely hollow and has a depth such that, when installing on the water a floating system for desalination that includes In said structure, the water rises and penetrates a small distance into the lower cavity, which contributes to the buoyancy of the system as a whole, and generating and maintaining a more stable temperature gradient inside the condensation and desalination structure. water by minimizing contact with the mass of water located outside the system, which will be at a different temperature. In a preferred embodiment, the lower base of the water condensation and desalination structure is delimited by a membrane or permeable surface that acts as a filter, controlling that only water enters the cavity, protecting the operation of the structure and at the same time preventing any living being from entering the cavity and suffering damage due to the high temperatures reached inside.

In an embodiment of the first object of the invention, the interior surface of the water condensation and desalination structure has, around its entire contour, a plurality of channels or grooves through which the water descends in a liquid state as a result of the condensation that is formed. It occurs when water vapor comes into contact with a cold body, such as the condensation and desalination structure of water.

In an embodiment of the first object of the invention, the desalinated condensed water collection structure comprises a collection pipe that connects to the lower base of said condensation and desalination structure. In a more preferred embodiment, the structure also comprises a pumping structure that allows the desalinated water to be transported.

A second object of the present invention constitutes a floating system for water desalination that comprises the water condensation and desalination structure using solar energy that constitutes the first object of the invention. In the case of circumstances in which solar radiation is not high enough, or simply as a support system, the system can include photovoltaic panels.

According to the above, a second object of the invention refers to a floating system for water desalination that comprises:

Yo. At least one water condensation and desalination structure according to the first object of the invention, which in turn comprises:

to. a plurality of solar collectors for collecting solar energy, and

b. a plurality of water evaporating elements; and

said structure (i) with a layout and geometry such that it allows the evaporating elements (b) to be in contact with the water on which the system floats; in this way promoting the evaporation of the water that covers the evaporating elements, evaporated water that is subsequently condensed once desalinated; and

ii. At least one floating modular structure, to which the structure (i) is anchored or integrated.

In an embodiment of the second object of the invention, the system comprises a plurality of joints that allow anchoring between adjacent floating modular structures and/or between the at least one floating modular structure and the at least one water condensation and desalination structure.

In an embodiment of the second object of the invention, the floating modular structure comprises a plurality of floating modules that facilitate its assembly and maintenance and that enable multiple configurations. In a preferred embodiment, said modules are made of a recyclable material, resistant both mechanically and against solar radiation, and environmentally friendly in the sense that it does not degrade or release toxic substances.

In an embodiment of the second object of the invention, the floating modular structure has its center free of floating modules in order to house in said space the at least one water condensation and desalination structure, said structure joined to the floating modular structure by means of joints. similar to those that allow the anchoring of said floating modular structure with adjacent floating modular structures. In a more preferred embodiment, it is possible that in the center of the floating modular structure two or more water condensation and desalination structures are housed, said structures joined together as well as, perimeter, to the floating modular structure in whose center of they locate. In this way, it is possible to form an “infinite network” of floating modular structures and water condensation and desalination structures.

In an embodiment of the second object of the invention, suitable for the case of circumstances in which solar radiation is not high enough, or simply as a support system, the system further comprises one or more photovoltaic solar panels supported by/on the structure. floating modular, therefore allowing the “infinite network” referred to above to be expanded. These photovoltaic panels make it possible to obtain energy for, for example, the operation of the pumping structure that allows transporting desalinated water.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1. Elevation view of an example of a water condensation and desalination structure (1) in accordance with the first object of the invention, showing a plurality of vacuum tubes (2) for the collection of solar energy, as well as a plurality of joints (3) for anchoring or integration in a floating system, a collection pipe (4) for desalinated condensed water, and a pumping module (5) for the movement or transportation of said water.

Figure 2. Plan view of an exemplary embodiment of a water condensation and desalination structure (1) showing a plurality of vacuum tubes (2) for the collection of solar energy, a plurality of anchoring joints (3) or integration in a floating system, as well as a detail of the lower base of said structure in which a hollow cavity (6) and a filtering structure (7) are located in which an opening is made for the collection pipe (4) of desalinated condensed water.

Figure 3. Isometric view of an example of realization of one of the vacuum tubes (2) that constitute the solar collector that is part of the water condensation and desalination structure and at one end of which an evaporator element (8) is located. .

Figure 4. Isometric view of an example of an embodiment of the floating system for water desalination using solar energy that is the object of the present invention, showing a water condensation and desalination structure (1) in accordance with the first object of the invention as well as a solar panel. photovoltaic (9) supported on the floating modular structure (10).

Figure 5. Plan view of an example of a floating modular structure (10) made up of a plurality of floating modules (11), including a detailed view of some of the joints (3) that allow anchoring between floating modular structures. adjacent and/or with/between water condensation and desalination structures.

Figure 6. Elevation view of a cross section of an embodiment of the floating system for water desalination using solar energy object of the present invention showing the modules (11) that make up the floating modular structure (10), the joints (3) that allow anchoring between adjacent floating modular structures and/or water condensation and desalination structures (1), a plurality of vacuum tubes (2) that constitute the solar collector integral to said water condensation and desalination structure, the lower cavity (6) of said water condensation and desalination structure (1), as well as the evaporator elements (8) located at each of the ends of the vacuum tubes (2).

PREFERRED EMBODIMENT OF THE INVENTION

The water condensation and desalination structure using solar energy for floating desalination systems object of the present invention, as well as a floating system that integrates said structure, are illustrated below by means of the following embodiment example, the nature of which is not limiting. In the specific case described here, the water condensation and desalination structure would be made of borosilicate glass, which has very beneficial properties for the correct functioning of the system, since it must behave like a cold body, supporting high temperatures, presenting a low thermal conductivity and at the same time a low coefficient of thermal expansion. It also has great resistance to thermal stress, high mechanical resistance and good resistance to UV radiation.

Figure 1 shows an elevation view of an exemplary embodiment of the water condensation and desalination structure using solar energy (1), including a plurality of vacuum tubes (2) as solar collectors, as well as a plurality of joints ( 3) anchoring or integrating into a floating system, a collection pipe (4) for desalinated condensed water, and a pumping module (5) for the movement or transportation of said water. The upper part of the structure maintains the same shape as the lower part, except that the upper part has an outward extrusion angle of 45° and a height of 70 cm, with the intention that the vacuum tubes (2) They can protrude from the structure to facilitate the capture of sun rays. As its name indicates, since the tube is empty, the heat does not escape and is transferred by convection to the two-phase thermosiphon tube (heat pipe), which works as a heat cycle inside, giving up all the heat by conduction. absorbed to the water that is in contact with the evaporator element of said tube (2). A heat transfer occurs, increasing the temperature of the water until it reaches its boiling point, in which part of the water goes from a liquid to a gaseous state, becoming vapor, which is dispersed throughout the interior of the condensation structure and desalination (1), which is sealed with a vacuum inside preventing gas escape. It is necessary that the temperature of the water be boiling and not reach a state of superheated water. The vacuum tubes (2) capture a lot of radiation, causing a very high temperature gradient to increase, so their properties must be regulated to achieve an optimal working temperature that does not exceed 140 °C, since in this way we would obtain dry steam. . The interior surface of the condensation and desalination structure has channels or grooves around its entire contour through which the water spray will descend in a liquid state as a result of condensation, when the water vapor comes into contact with a cold body, such as the condensation and desalination structure. The condensed water is channeled to the main collection pipe (4) responsible for collecting the desalinated condensed water for subsequent transport through the pumping structure (8).

Figure 2 shows a plan view of an exemplary embodiment of the water condensation and desalination structure using solar energy (1), including a plurality of vacuum tubes (2) for the collection of solar energy, a plurality of joints (3) for anchoring or integration in a floating system, as well as a detail of the lower base of said structure in which a hollow cavity (6) and a drilled sheet as a filtering structure (7) are located in which a opening for the collection pipe (4) of desalinated condensed water. The lower base is submerged in water,

Figure 3 shows an isometric view of an example of an embodiment of one of the vacuum tubes (2) that constitute the solar collector that is part of the water condensation and desalination structure and at one end of which an evaporator element is located ( 8). The vacuum tubes (2) have a height of 1.8 m, which allows them to protrude from the condenser structure to capture all possible solar radiation. Inside they consist of a two-phase thermosiphon tube, which has high conductivity and is responsible for transferring heat through the evaporator element (8). This heat transfer device combines thermal conductivity inside with a phase change from liquid to vapor that favors heat transport.

Figure 4 shows an isometric view of an example of an embodiment of the floating system for water desalination using solar energy that is the object of the present invention, showing a water condensation and desalination structure (1) in accordance with the first object of the invention as well as a photovoltaic solar panel (9) supported on the floating modular structure (10). Thanks to the photovoltaic solar panel installation (9), it is possible to obtain energy and accumulate it in batteries to transfer it, for example when it is not sunny, to the resistors with the aim of carrying out the evaporation, condensation and desalination process, or to the pumping structure. responsible for transporting desalinated water.

Figure 5 shows a plan view of an example of a floating modular structure (10) made up of a plurality of floating modules (11), including a detailed view of some of the joints (3) that allow anchoring between structures. floating modular units adjacent to and/or with/between water condensation and desalination structures. In this example of embodiment, the modules (11) that make up the floating modular structure are high-density polyethylene (HDPE) cubes. These cubes are joined together by means of specific joints (2), forming a floating assembly with a quadratic base that, in its center, is free of structural modules to connect a water condensation and desalination structure. Each floating modular structure is made up of 48 modules and occupies an area equal to 16 m2. Right in the center of the base, the condensation and desalination structure will be located, which will be joined to the floating platform (10) using the same specific joints (2) that join the modules (11). The high-density polyethylene (HDPE) modules (11) that make up the floating modular structure (10) support a resistance of 360 Kg/m2. The floating modular structure (10) does not need special maintenance as it is 100% high-density polyethylene (HDPE), and is also completely recyclable, non-harmful and does not harm the environment since it does not contain or release corrosive or oxidizing materials. The polyethylene modules (11) are very light, stable and safe since their surface is non-slip. They are also resistant to UV rays and very resistant to adverse atmospheric conditions.

Figure 6 shows an elevation view of a cross section of an embodiment of the floating system for water desalination using solar energy that is the object of the present invention, showing the modules (11) that make up the floating modular structure (10), the joints ( 3) that allow anchoring between adjacent floating modular structures and/or water condensation and desalination structures (1), a plurality of vacuum tubes (2) that constitute the solar collector that is part of said water condensation and desalination structure , the lower cavity (6) of said water condensation and desalination structure (1), as well as the evaporator elements (8) located at each of the ends of the vacuum tubes (2). At the top of the water condensation and desalination structure (1) there is an empty extrusion in the shape of an inverted cone, allowing the solar collectors (2) to be installed with the correct inclination to capture the greatest solar radiation per hour of sunshine. . The depth of the cone is such that its lower base is submerged in the water, so that the evaporator elements (8) are in contact with the water that penetrates the water condensation and desalination structure, which is hollow. in its entirety, with a trapezoidal sheet shape 4 cm thick, with an internal extrusion angle of 50° and with a depth such that when the structure is introduced into the water, it penetrates a small distance into the cavity (6) . The diameter of the upper base measures 2.6 m and the diameter of the lower base measures 0.8 m. The system is not only suitable for desalinating the water on which it is installed, but it also allows rainwater to be collected and subsequently treated. One of the reasons for the efficient operation of the present invention compared to existing systems that constitute the state of the art is that, at the lower base of the cone, the evaporator elements (8) of the solar collectors (3) are installed. They make up the vacuum tubes, with an inclination of 50°, as mentioned above. Here it is also possible to avoid the problems of known desalination systems, since the vapor clouds generated by the increase in temperature do not affect the correct functioning of the system, since the solar radiation is focused on the solar collectors (3), which They are always in contact with the water surface through the evaporator elements (8). Still-traditional solar systems increase the temperature of the water due to the Greenhouse effect produced by solar radiation that hits the transparent cover, so when the water changes to a gaseous state, it limits the passage of solar radiation due to the existing gas cloud. Traditional still solar systems have a production between 1 and 4 liters of water per m2 of surface covered by the system. With the system proposed in the present invention it is possible to obtain a greater amount of water since it allows the number of condensation and desalination structures to be increased and these exhibit significantly different functioning.

Claims (8)

1. Water condensation and desalination structure using solar energy for floating desalination systems characterized by: to. It presents a geometry essentially of a cone or inverted pyramid whose upper part opens, extrudes or projects outwards, and whose lower part is hollow and open so that, once the structure is installed on a mass of water, it rises and penetrates, contributes to buoyancy and the generation and maintenance of a temperature gradient; and b. understands: Yo. a plurality of solar collectors (2) arranged inclinedly and radially on the internal wall of the geometry, ii. a plurality of evaporator elements (8) located or connected at the lower ends of the solar collectors (2), the "lower end" being understood as that end that is oriented towards the center or interior of the structure, and whose free ends, once the structure is installed over a body of water, they come into contact with water that rises and penetrates through the bottom of the structure's geometry, and iii. a collection pipe (4) that connects to the lower part of the structure for the collection of desalinated water in a liquid state resulting from condensation. 2. Water condensation and desalination structure using solar energy for floating desalination systems according to the previous claim, characterized in that the solar collectors (2) protrude from the geometry of the structure to facilitate the capture of sun rays. 3. Water condensation and desalination structure using solar energy for floating desalination systems according to the previous claim, characterized in that the solar collectors (2) consist of vacuum tubes. 4. Water condensation and desalination structure using solar energy for floating desalination systems according to any of the previous claims, characterized in that its lower part is delimited by a membrane or permeable surface that acts as a filtering structure (7). 5. Water condensation and desalination structure using solar energy for floating desalination systems according to any of the previous claims, characterized in that its interior surface has a plurality of channels or grooves through which the desalinated water descends in a liquid state as a result of condensation. . 6. Water condensation and desalination structure using solar energy for floating desalination systems according to any of the previous claims, characterized in that it comprises a pumping module (5) that allows transporting the desalinated water in a liquid state as a result of condensation. 7. Floating system for water desalination characterized in that it comprises: to. at least one water condensation and desalination structure using solar energy (1) according to any of the preceding claims, and b. at least one floating modular structure (10) to which the at least one water condensation and desalination structure using solar energy (1) is anchored or integrated. 8. Floating system for water desalination according to the preceding claim characterized in that it further comprises one or more photovoltaic solar panels (9) supported by/on at least one floating modular structure (10).