ES2961413B2 - AUTONOMOUS SOLAR DISTILLER FOR MICRO-IRRIGATION WITH RAINWATER FROM FOREST AND AGRICULTURAL PLANTS - Google Patents

Description

DESCRIPTION

Autonomous solar distiller for micro-irrigation with rainwater of forest and agricultural plants

Technical field of the invention

The present invention corresponds to the technical field of agriculture and forest plantation, specifically to an autonomous solar distiller that allows micro-irrigation of these plantations using rainwater.

Background of the Invention

The growing problems caused by climate change and increasing levels of water stress due to lack of water in all regions of the world are now well known. This is why it is necessary to emphasize the urgent need to create resilient water management systems, so that every drop of water counts.

The Food and Agriculture Organization of the United Nations (FAO) and the International Commission on Irrigation and Drainage (ICID) have adopted the terms "localized irrigation" or "micro-irrigation" to define irrigation systems that allow optimal use of water. In these systems, small quantities of water infiltrate directly to the roots of plants, increasing productivity and irrigation yield per unit of surface area.

In the agricultural sector, the existence of these micro-irrigations is especially recommended in arid and/or remote areas, far from urban centers, where there are limitations on the availability of water in the quality and quantity necessary throughout the production cycle.

In the forestry sector, the need for these micro-irrigations is evidenced by the low success that reforestation usually has using traditional methods. The sowing of forest species, as well as the establishment of seedlings in reforestation is one of the critical points of the restoration/repopulation process in Mediterranean conditions and in general in all regions of the world with marked water stress. To help in this process, different devices and systems have been developed in recent years that have been used operationally in forest restoration programs, such as protective tubes, hydrogels, organic amendments, micro-basins, etc., in order to help the plant develop a more functional root system in the period from planting to the appearance of summer water stress.

Providing support irrigation in the first years of a reforestation greatly increases the survival capacity of the plants. But this support irrigation is not always viable, either due to the difficulty of access due to the very nature of the land where the action is carried out, or due to the impossibility of bearing the costs involved in transporting water for irrigation, since we are talking about reforestation on large surfaces, with complex access in most cases, and these are not actions that can be assumed on a forest scale.

In this sense, several types of devices have been developed whose objective is the irrigation of plants in these cases, and as an example of the state of the art, reference documents WO2015063243, ES2304905, ES2351840, EP3885017A1, DE2626902A1, and DE102004053728A1 can be mentioned.

Reference document WO2015063243 defines a seedling planting apparatus, which includes a reservoir and a cover, the reservoir being below ground level. This reservoir includes a container filled with water and irrigation means for providing a controlled flow of water from the container, formed by capillary wicks that allow the supply of water to the lower area of the ground.

This irrigation system using a capillary wick has proven to have certain drawbacks over time, as it requires maintenance that is not usually possible under the conditions in which these plantations are grown. Thus, the capillary wick used to direct the water contained in the tank towards the bottom of the soil where the plant roots are located becomes clogged over time and needs to be replaced with a new one, which means removing the buried device in order to replace the wick that is usually connected to the bottom of the tank.

In addition, for this system to work, it is indicated that it is necessary to carry out an initial filling artificially to ensure the initial functionality of the wick. Thus, although it will subsequently be filled with rainwater, this initial filling must be carried out by the operators, which requires time, labour and resources to transport the water to the repopulation sites, which may not be easily accessible.

These drawbacks are of significant importance, since when reforestation of a forest or plantation is being carried out on a large or difficult-to-access area, these problems cannot be considered, since maintenance and/or initial filling of the devices with water is not feasible. This creates a major problem of effectiveness in this type of device.

Reference document ES2304905 describes a device consisting of a terracotta container with an upper filling mouth and holes below the level of said filling mouth.

From said holes come out threads of synthetic fibres, which have at least one inner section with one end extended inside the container up to a weight at its bottom, and an outer section arranged on the outer surface of the container in a knotted or intertwined manner, in contact with the ground, suitable so that once the container is buried up to the level of the upper mouth, the threads carry out a gradual transfer of water between the inside and the outside of the container by capillarity.

This device works by means of capillarity through synthetic fibre threads, in a similar way to the first document mentioned, which worked through a capillary wick and presents the same drawbacks in terms of clogging of the threads and the need for maintenance, in addition to not capturing rainwater for filling.

Reference document ES2351840 determines a rainwater collection tank for irrigation with a protective effect like a nurse plant, which comprises a tank for collecting and storing rainwater, which incorporates a device for delayed discharge of water to a plant, and a structure for protecting the plant from external agents, formed by a cylindrical protector reticulated with shading mesh.

This document lists different delayed discharge mechanisms to provide irrigation water to the plant, including valves, microtubes, fibres and clay. In practice, for these devices the only viable mechanisms for irrigation, of those described in the document, would be fibres or wicks and clay, where the most common is the use of ceramic cones, since the valves and microtubes, which are not observed in practice, should not work beyond several days, since they require pressure to operate and these systems do not provide it, and they would have problems with air entering inside them, having to be purged for their operation. Clay or ceramic cones present the same problem as wicks, the loss of capillarity over time and they must be replaced periodically, which again is a major inconvenience when we talk about reforestation or crops in remote areas.

In addition to these problems, this device, like the first one mentioned, needs to be artificially filled during its installation phase in order to function.

The devices in the documents seen so far have two main problems. The first is that they use water outlet systems to the plant that become clogged over time, ceasing to be functional if they are not periodically checked, which makes them more expensive to use and difficult to use. The second problem is that there is currently no such device that can be installed next to the plant without water, waiting for it to fill naturally with rainwater, which would also make their use considerably cheaper and easier.

All these problems have generated a search for more efficient irrigation systems, understanding that the most suitable method to solve the first problem is to use devices based on solar distillation, which is an irrigation technique that allows for optimal use of water by using the sun's energy as the driving force of the distillation process and movement of water. These devices have a water tank and a transparent cover so that water is supplied to the plant by condensation, increasing its performance in the summer period. There is no mechanism for water to flow to the plant, only the dripping of condensed water, which is what irrigates the plant.

These irrigation systems are activated to a greater extent on the hottest days with the lowest relative humidity, which are precisely those in which the plant is subjected to greater water stress. A micro-irrigation system using solar distillation can solve the problems presented by capillary irrigation systems (wicks, ropes or ceramic pieces), which by their very nature have a finite lifespan on the ground, and must be replaced periodically, which is a major drawback when we are talking about reforestation or crops in remote areas.

An example of this is the case of reference document EP3885017A1, which defines a device that produces distilled water with solar radiation from contaminated water. This distiller has a first container, to contain contaminated water, an outer cover, a water collection unit and an inner cover to enclose a volume in the first container. The inner and outer covers are designed to transport condensed water to the water collection unit, the outer cover being transparent to heat the contaminated water in the first container by solar radiation, although it can also be provided with electrical heating means, or both.

This device does not solve the second problem mentioned above, since it is not an autonomous device, as it is necessary to supply a volume of contaminated water with which to start the distillation process. This brings an additional complication in the case of reforestation and large areas.

Reference document DE2626902A1 defines a large-area solar distillation system for non-fresh water using a gas-tight cover made of a pneumatically stabilized transparent plastic cover. The system serves as a greenhouse for growing plants, for which non-fresh water is circulated over an optical filter and condensed and collected in a fresh water tank.

This system does not direct irrigation water directly to the plants, but instead serves to distill salt water, obtaining a volume of fresh water. The additional problem is that it is not possible to use rainwater for this, but rather it is necessary to provide the volumes of salt water to be distilled. Therefore, it requires continuous maintenance to restore the volumes as the water evaporates.

In the case of reference document DE102004053728A1, it also refers to a solar distiller for salt water or contaminated water, which implies the need to initially and periodically provide a volume of said water to be distilled, in order to obtain a corresponding volume of fresh water for irrigation.

All these solar stills have the problem that they are not autonomous, since they need to be filled manually to allow them to function, and they are not rainwater collectors. In addition, to fill the water, it is necessary to manipulate the device, with the opening of the cover to allow access to the water tank area necessary for distillation. This complicates the process greatly.

There is therefore currently a serious problem in the field of agriculture and forestry plantations that needs a solution, since the devices available to provide micro-irrigation to plants all have a series of drawbacks that either require maintenance work and initial actions on them, which complicate the use of these devices in large and/or inaccessible areas, or require a continuous supply of salt or contaminated water to provide a volume of fresh water from the condensation of the former. Thus, none of them can be considered an autonomous device that allows effective micro-irrigation in large or difficult-to-access areas and all of them involve a high manufacturing cost, making their use on a large scale more difficult.

Description of the invention

The autonomous solar distiller for micro-irrigation with rainwater of forest and agricultural plants presented here comprises a water collection and containment tank located buried below ground level and a cover fixed over the tank at a level higher than that of the ground, being arranged on or at ground level, which has a concave shape towards the outside and a hole for collecting rainwater.

In this solar still, the cover comprises a minimum level located at a distance from the centre of the same and a horizontal section connecting the minimum level and the collection hole, such that said collection hole is located at that same minimum level.

Furthermore, in this solar distiller, the tank comprises a water containment area from the base of the tank to a maximum level lower than the minimum level of the cover, and an overflow opening towards the ground located at said maximum level capable of allowing the overflow of the contained water, where said overflow opening is located in correspondence with the minimum level of the cover such that it is also capable of allowing the exit of the water condensed on the cover.

The autonomous solar still for micro-irrigation with rainwater of forest and agricultural plants proposed here represents a significant improvement in the state of the art.

This is because a completely autonomous device is achieved, which, once installed, is filled naturally with rainwater, so its installation is simple and fast, requiring no prior action or initial filling or purging. The installation is only carried out with the tank buried next to a seedling, or with the seedling located concentric with the device, and such that the cover is located at ground level or above it, so that, with the first rains, the device begins to fill with water and starts to operate.

Furthermore, it has a design that allows for mass production and stacking of the pieces, making them stable in their placement and use.

With this device, the water produced is directed right to the root of the plant that is being irrigated, making this irrigation very effective and beneficial for the plant.

Likewise, this device presents two irrigation options directed towards the roots of the plant.

The first of these is the one already mentioned by condensation, since the water condensed on the lower surface of the roof is all directed towards the minimum level of the roof, so that when it falls it does so through the spillway opening, right where the root of the plant is in the ground.

On the other hand, the second irrigation option occurs in the case where, during periods of heavy rainfall, an amount of water is collected that exceeds the containment volume of the tank of this device, since all the excess water comes out through this same overflow opening and also irrigates the roots of the plant directly.

This increases the availability of water supply to the plant beyond that obtained by distillation.

It is a completely autonomous device, as it works without the need for any type of maintenance, since there are no elements that lose effectiveness, nor is it necessary to add any water at any time. However, it allows an additional mode of use, if desired, in which the manual filling of the tank with salt water or contaminated water is possible, in which case the device continues to function effectively, without the need for manipulation or maintenance.

Furthermore, this device can operate in two modes: first, it is placed buried adjacent to the plant to be watered, and second, it is placed buried with the plant in the central area of the device, so that the irrigation water reaches not only one side of the plant but also the entire perimeter around it.

It is therefore a completely effective solar distiller in the objective set out here, as it manages to combine the capacity for autonomy by supplying itself with rainwater, the durability of the system's operation, in terms of the irrigation motor, which is solar energy, and at the same time it allows the water to be placed close to the plant at the time it is most needed, being a simple and easy-to-produce system that can entail a low cost for its application on a large scale in reforestation or agricultural plantations.

This solar distiller makes it possible to complete the production cycle of agricultural plants and, in the case of perennial or forest plants, to ensure a sufficiently developed root system so that it is able to subsist on its own. At this point, once its function of supporting the development of the plants in their first years of life has been fulfilled, the device is completely reusable and can be moved to another location for a new use.

Brief description of the drawings

In order to assist in a better understanding of the characteristics of the invention, in accordance with a preferred example of its practical implementation, a series of drawings is provided as an integral part of said description, where, for illustrative and non-limiting purposes, the following has been represented:

Figure 1.- Shows a perspective view of the cover of a solar still, for a first preferred embodiment of the invention.

Figures 2.1, 2.2 and 2.3 show plan, elevation and profile views with a view of detail A of the cover of a solar still, for a first preferred embodiment of the invention.

Figure 3.- Shows a perspective view of the tank of a solar still with a view of detail B, for a first preferred embodiment of the invention.

Figures 4.1, 4.2 and 4.3 show plan, elevation and profile views of the tank of a solar still, for a first preferred embodiment of the invention.

Figure 5.- Shows a perspective view of a solar still, for a first preferred embodiment of the invention.

Figures 6.1, 6.2 and 6.3 show plan, elevation and profile views of a solar still, for a first preferred embodiment of the invention.

Figure 7.- Shows a schematic view of the operation of a solar distiller, for a first preferred embodiment of the invention.

Figure 8.- Shows a perspective view of the cover of a solar still, for a second preferred embodiment of the invention.

Figures 9.1, 9.2 and 9.3 show plan, elevation and profile views of the cover of a solar still, for a second preferred embodiment of the invention.

Figure 10.- Shows a perspective view of the tank of a solar still with a view of detail C, for a second preferred embodiment of the invention.

Figures 11.1, 11.2 and 11.3 show plan, elevation and profile views of the tank of a solar still, for a second preferred embodiment of the invention.

Figure 12.- Shows a perspective view of a solar still, for a second preferred embodiment of the invention.

Figures 13.1, 13.2 and 13.3 show plan, elevation and profile views of a solar still, for a second preferred embodiment of the invention.

Figure 14.- Shows a schematic view of the operation of a solar distiller, for a second preferred embodiment of the invention.

Detailed description of a preferred embodiment of the invention

In view of the figures provided, it can be observed how in a first preferred embodiment of the invention, the autonomous solar distiller for micro-irrigation with rainwater of forest and agricultural plants proposed here, comprises a tank (1) for collecting and containing water located buried below ground level and a cover (2) fixed on the tank (1) at a level higher than that of the ground, which has a concave shape towards the outside and a rainwater collection hole (3).

The cover (2) of this solar distiller comprises a minimum level located at a distance from the center thereof and a horizontal section (4) connecting the minimum level and the collection hole (3), as shown in Figures 1, 2.1, 2.3, 5, 6.1 to 6.3 and 7, such that said collection hole (3) is located at that same minimum level.

On the other hand, the tank (1) comprises a water containment area (1.1) from the base of the tank (1) to a maximum level lower than the minimum level of the cover (2), and an overflow opening (5) towards the ground located at said maximum level capable of allowing the overflow of the contained water, where said overflow opening (5) is located in correspondence with the minimum level of the cover (2) such that it is capable of allowing the exit of the water condensed in the cover (2).

In a first preferred embodiment of the invention, the cover (2) has the shape of a cone or oblique pyramid, and its minimum height is formed by an eccentric vertex (6), as can be seen in Figures 2.2, 2.3, 6.1, 6.3 and 7.

Furthermore, in this first embodiment, as shown in Figure 2.3, the distiller comprises an apex-shaped part (7) for collecting condensation, fixed to the vertex (6) of the cover. In this way, the fall of the condensed water is directed more precisely towards the desired location.

Furthermore, in this first preferred embodiment, the tank (1) comprises a tubular channel (17) that emerges from the base of the tank (1) and is located closer to the outer contour of said base, as shown in Figures 3, 4.2, 4.3, 5, 6.2, 6.3 and 7. Said tubular channel (17) forms the spillway opening (5) of the tank (1).

In other embodiments, the distiller may further comprise an extension of the tubular channel (17) from the base of the tank (1) towards the ground. In this way, a greater depth of irrigation would be achieved, which may be necessary for certain types of plants.

Furthermore, in this first embodiment, the tank (1) has a section whose dimension increases with height, while the tubular channel (17) emerging from its base has a section whose dimension decreases with height. In this specific case, both the tank (1) and the tubular channel (17) have a truncated cone shape, although in other embodiments they may have a different shape, such as a truncated pyramid.

This condition of increasing section for the case of the tank and decreasing with height for the case of the tubular channel allows the stacking of said tanks (1) of the distillers, for better and simpler transport and storage.

The spillway opening (5), as shown in Figures 5, 6.1 to 6.3 and 7, is aligned with the area where the drops fall from the cover (2), that is, with the vertex (6) that materializes the minimum height of the cover (2) in this first embodiment, so that the outlet of said condensed drops goes directly to the ground and thus performs micro-irrigation to the plant. This tubular channel (17) that forms the spillway opening (5) is located as close as possible to the contour of the tank (1), so that it is also located as close to the plant as possible, in order to increase the efficiency of the operation.

In this first preferred embodiment of the invention, the cover (2) is joined by its outer contour to the outer contour of the tank (1) by means of hermetic joining means. To facilitate assembly, both the cover and the tank have a sign indicating how they should be joined so that the vertex (6) of the cover and the spillway opening (5) are aligned.

When joined in this way, a microclimate is generated inside the distiller with an increase in temperature due to the action of solar radiation, producing the evaporation of the water stored in the tank (1), which subsequently condenses on the inside of the cover (2), forming drops that when they acquire the necessary size and weight and due to the action of gravity, are directed to the minimum level of the cover (2), formed by a vertex (6) from where they will be detached.

As shown in Figures 1, 2.2, 2.3, 5, 6.2, 6.3 and 7, in this first preferred embodiment, the cover (2) comprises a rainwater inlet conduit (8) with a first end (8.1) connected to the collection hole (3) and a second end (8.2) located above the containment area (1.1) of the tank (1) and whose length is equal to or less than the distance between said collection hole (3) and the base of the tank (1). Thus, by placing said second end (8.2) very close to the base of the tank (1), the entry of outside air into the interior thereof is prevented, favouring the distillation process inside the distiller.

This water inlet conduit (8) for filling the tank (1) is offset with respect to the spillway opening (5), which in this first embodiment is formed by the tubular channel (17) that emerges from the base of the tank (1), thus preventing the water collected by the upper part of the cover (2) from exiting directly through the spillway opening (5) towards the ground, as shown in Figures 5, 6.1 to 6.3 and 7.

In this first preferred embodiment, the inlet duct (8) is connected to the collection hole (3) by means of removable connection means. In this way, it is possible to disconnect it for easier storage and transport of the distiller elements.

In other embodiments, such as in a second embodiment which will be seen later, it may occur that the inlet duct (8) is connected to the collection hole (3) by means of a solid joint.

In this first preferred embodiment of the invention, the tank comprises means of anchoring it to the ground, as shown in Figures 3, and 4.1 to 4.3.

These anchoring means are made up of pegs that are inserted through the entry hole of some slots (9) existing in the base of the tank (1) to prevent it from tipping over in adverse weather conditions in the area, especially strong winds.

The cover (2) of this solar still is made of transparent or translucent material, so that it allows the passage of sunlight, evaporating the water inside the tank (1). The case of a translucent cover (2) can be very interesting for those cases in which the temperatures are excessively high, so that with the translucent cover the performance can be reduced to avoid excessively accelerated condensation of the water in the tank.

Thus, once the solar distiller is installed, the first rains start filling the tank (1), and if the volume of the tank is exceeded, the water would be released through the overflow opening (5) watering the roots directly. The water contained in the tank is subjected to the distillation process, so that the drops condensed on the lower surface of the cover (2) run to the vertex (6) of the same and the apex (7) existing at this vertex (6) favors the fall of the drops at that point. All the drops accumulated on the cover (2) are directed to that apex (7) except those that in their direction touch the horizontal section (4) connecting the vertex (6) with the collection hole (3), which fall back to the tank (1).

In a second preferred embodiment of the invention, as can be seen in Figures 8 and 9.1 to 9.3, the cover (2) has a central opening (10) capable of allowing the passage of a floor and the minimum height in this case is located along a ring (11) concentric with said central opening (10) and closer to the central opening (10) than to the outer contour of the cover (2).

In this case, as shown in Figures 10 and 11.1 to 11.3, the tank (1) comprises a tubular channel (17) concentric with the tank (1), which forms the spillway opening (5). This tubular channel (17) emerges from the bottom of the tank (1) at a distance from the outer contour of the tank (1) such that the ring (11) with minimum elevation of the cover (2) is arranged in correspondence with the interior space of said spillway opening (5).

As shown in Figures 13.2 and 13.3, in this second preferred embodiment of the invention, the distiller also comprises a rainwater inlet conduit (8) with a first end (8.1) connected to the collection hole (3) and a second end (8.2) located above the containment area (1.1) of the tank (1) and whose length is equal to or less than the distance between said collection hole (3) and the base of the tank (1).

In this second embodiment, this inlet duct (8) is connected to the collection hole (3) by means of a solid joint. Furthermore, in this case, said inlet duct (8) has a section that decreases from the first end (8.1) towards the second end (8.2), to facilitate the stacking of the covers of different distillers, for their transport and storage.

As shown in Figures 10, 11.2, 11.3 and 12, in this second preferred embodiment the tank also has a section that increases with height, specifically in a truncated cone shape, while the tubular channel (17), in this case concentric, has a section that decreases with height and is also in a truncated cone shape, which also allows for easy transport and storage of the tanks.

In this second preferred embodiment of the invention, the tank (1) and the cover (2) also have first means for hermetically sealing the outer contour of both and second means for connecting the central opening (10) of the cover (2) to a circular piece (12) of the tank (1) connected to the spillway opening (5). In this case, the connection of the circular piece (12) to the spillway opening (5) is formed by radial connection elements (13) that divide the spillway opening (5) of the tank (1) into sections (14), as can be seen in Figures 10 and 11.1.

In other preferred embodiments, said second connecting means are formed by a connection grid over the spillway opening (5).

In this second preferred embodiment, the circular piece (12) of the tank (1) has a central channel (15) for plant protection, which emerges from it towards the upper part of the cover (2), as shown in Figures 12, 13.2, 13.3 and 14. This central channel (15) protects the plant inside from the possible presence of rodents in the planting area.

Specifically in this case, said central protection channel (15) comprises holes (16) for ventilation of the plant on its lateral surface.

In this second embodiment, as in the first proposed embodiment, once the device is placed on the ground with the plant, the installation is complete. When it starts to rain, the cover (2), having a concave shape like a funnel, directs the water towards the minimum level which in this case is a circular ring (11) in the centre and from it, being connected to the collection hole (3), it runs towards the inside of the tank (1).

The tank (1) stores rainwater from the roof (2) in the containment area (1.1). When full, any rainwater that continues to be collected by the roof (2) overflows through the overflow opening (5) through its sections (14), providing more water to the plant in addition to that generated by solar distillation.

The micro-irrigation process occurs in this case because the drops accumulated on the inside of the cover (2) fall to the ring (11) of the cover (2) that forms the minimum level, from where they are released, entering through the sections (14) of the overflow opening (5) of the tank (1), to fall on the ground around the plant.

In other preferred embodiments of the invention, the cover (2) comprises folds and/or undulations capable of increasing the effective condensation surface of the evaporated water in the tank.

Likewise, in other embodiments the distiller comprises water absorption means in the contact area of the water droplets with the ground, formed by a geotextile material and/or a hydrogel.

This distiller is preferably made from biodegradable and/or reusable materials, with the aim of being respectful of the environment.

The embodiments described herein are merely examples of the present invention, therefore, the specific details, terms and phrases used herein are not to be considered as limiting, but are to be understood only as a basis for the claims and as a representative basis that provides an understandable description as well as sufficient information to the person skilled in the art to apply the present invention.

Claims (1)

1- Autonomous solar distiller for micro-irrigation with rainwater of forest and agricultural plants, comprising a water collection and containment tank (1) located buried below ground level and a cover (2) fixed on the tank (1) at a level higher than that of the ground, which has a concave shape towards the outside and a rainwater collection hole (3), characterized in that - the cover (2) comprises a minimum level located at a distance from the centre thereof and a horizontal section (4) connecting the minimum level and the collection hole (3), such that said collection hole (3) is located at the same minimum level, and; - the tank (1) comprises a water containment area (1.1) from the base of the tank to a maximum level lower than the minimum level of the cover (2), and an overflow opening (5) towards the ground located at said maximum level capable of allowing the overflow of the contained water, where said overflow opening (5) is located in correspondence with the minimum level of the cover (2) such that it is also capable of allowing the exit of the water condensed therein. 2- Distiller, according to claim 1, wherein the cover (2) is shaped like a cone or oblique pyramid, and its minimum height is formed by an eccentric vertex (6). 3- Distiller, according to claim 2, comprising an apex-shaped piece (7) for collecting condensation, fixed to the vertex (6) of the cover (2). 4- Distiller, according to any of the preceding claims, wherein the tank comprises a tubular channel (17) that emerges from the base of the tank (1) and is closer to the outer contour of said base, wherein said tubular channel (17) forms the overflow opening (5). 5- Distiller, according to claim 4, comprising an extension of the tubular channel (17) from the base of the tank (1) towards the ground. 6- Distiller, according to any of the preceding claims, wherein the cover (2) is joined by its outer contour to the outer contour of the tank (1) by means of hermetic joining means. 7- Distiller according to claim 1, wherein the cover (2) has a central opening (10) capable of allowing the passage of a plant and the minimum height is located along a ring (11) concentric with said central opening (10) and closer to the central opening (10) than to the outer contour of the cover (2). 8- Distiller, according to claim 7, wherein the tank (1) comprises a tubular channel (17) concentric with the tank (1), which forms the overflow opening (5) and emerges from the bottom thereof at a distance from the outer contour such that the ring (11) with minimum height of the cover (2) is arranged in correspondence with the interior space of said overflow opening (5). 9- Distiller, according to any of claims 7 or 8, wherein the tank (1) and the cover (2) have first hermetic joining means of the outer contour of both and second joining means of the central opening (10) of the cover (2) with a circular piece (12) of the tank (1) connected to the overflow opening (5) thereof. 10- Distiller, according to claim 9, wherein the second connecting means are formed by radial connection elements (13) that divide the overflow opening (5) of the tank (1) into sections (14). 11- Distiller according to claim 9, wherein the second connecting means are formed by a connection grid over the overflow opening (5). 12- Distiller, according to any of claims 7 to 11, wherein the circular piece (12) has a central channel (15) for protecting the plant that emerges from it towards the upper part of the cover (2). 13- Distiller, according to claim 12, wherein the central protection channel (15) comprises holes (16) for aeration of the plant on its lateral surface. 14- Distiller, according to any of the preceding claims, wherein the tank (1) has a section increasing with height. 15- Distiller, according to any of claims 4, 5 or 8, wherein the tubular channel (17) has a section decreasing with height. 16- Distiller, according to any of the preceding claims, comprising a rainwater inlet conduit (8) with a first end (8.1) connected to the collection hole (3) and a second end (8.2) located above the containment area (1.1) of the tank (1) and whose length is equal to or less than the distance between said collection hole (3) and the base of the tank (1). 17- Distiller according to claim 16, wherein the inlet duct (8) is connected to the collection hole (3) by means of removable connection means. 18- Distiller, according to claim 16, wherein the inlet duct (8) is connected to the collection hole (3) by means of a solid joint. 19- Distiller, according to claim 18, wherein the inlet duct (8) has a decreasing section from the first end (8.1) towards the second end (8.2). 20- Distiller, according to any of the preceding claims, wherein the cover (2) is formed by a transparent or translucent material. 21- Distiller, according to any of the preceding claims, wherein the tank (1) comprises means of anchoring to the ground. 22- Distiller, according to any of the preceding claims, wherein the cover (2) comprises folds and/or undulations capable of increasing the effective condensation surface of the evaporated water in the tank. 23- Distiller, according to any of the preceding claims, comprising water absorption means in the contact area of the water drops with the ground, formed by a geotextile material and/or a hydrogel.