Energy-saving seawater desalination using sunlight

Abstract

Seawater desalination or deionization of water by sunlight, characterized in that the seawater desalination plant comprises an evaporation basin with seawater, the bottom of which is lined with a black (e.g. pond) absorber foil.

Description

[0001] For a very long time, "freshwater" has been obtained from saltwater through sunlight / solar heat and evaporation. In this context, it is important to know that the Earth's usable water resources are limited and becoming increasingly scarce. Depending on the source, 97.5% of all water is saltwater, and of the remaining 2.5%, only 3% is accessible. Water with a salinity below 0.1-0.2% is often referred to as freshwater and requires further treatment to be suitable for drinking. Several methods exist for seawater desalination, but only a few produce the vast majority of freshwater (evaporation, pressure, etc.). Pressure and heat account for 25-50% of the costs. Given that over two billion people worldwide lack access to drinking water, new, energy-efficient, affordable, and simple solutions are urgently needed.

[0002] The invention relates to a device for desalinating seawater by solar evaporation and condensation - water treatment by distillation using solar energy.

[0003] The basic idea is based on the well-known principle of the "Solar Still." A black basin and a transparent, sloping cover with condensation on the inside, as well as drainage of the condensate into a collection channel, represent state of the art. Solar desalination systems with a basin, transparent cover, and condensate collection have been patented for decades. Fans to improve condensation have also been proposed.

[0004] New features include a flexible foil structure instead of a rigid construction, the use of wind for active vapor movement, drip trays as structural and functional elements, an adaptive foil structure (erectable, retractable, weighted), multi-layer foils with a vapor-permeable middle layer, and a low-tech concept with minimal infrastructure.

[0005] Since there are many different methods for seawater desalination, only a few further examples are listed here: In electrodialysis, ions are electrochemically separated from uncharged particles in ion exchange membranes using an applied electrical voltage. Stacks of electrically alternating membranes consist of many pairs. This results in an accumulation of salts in one area of ​​the stack and a reduction in salt concentration in another. The energy required for electrodialysis separations is proportional to the salt concentration. For this reason, electroosmosis is more efficient at low salt concentrations than, for example, reverse osmosis, in which the salt solution is forced through a semipermeable membrane under high pressure. Capacitive deionization requires only porous carbon electrodes and electricity. It is based on a reversible electrochemical principle. The ions are absorbed into the electrode material. Ideally, for every electron at the anode and every positive charge at the cathode, one cation and one anion are absorbed. Research is also being conducted on new carbon nanomaterials such as graphene or so-called "carbon nanoonions" regarding the storage of these ions as energy storage media.

[0006] Other interesting approaches to seawater desalination / deionization include desalination using a gel (Institute for Technical Chemistry and Polymer Chemistry at the Karlsruhe Institute of Technology (KIT), "hydrogel"). Crucial to this process are electrically charged molecular groups that retain dissolved salts as they penetrate the gel. When the swollen absorber is squeezed, the emerging water has a much lower salt concentration than before. Another idea is to use less energy by removing salt compared to producing water (Adionics SAS: AquaOmnes).

[0007] Known systems have problems such as: high construction costs, rigid designs, lack of scalability, inefficient use of wind, limited condensation areas, high material usage and complex technology.

[0008] The general problem of seawater desalination / deionization of water is to produce fresh water cheaply, energy-efficiently and in large quantities.

[0009] Many solutions exist for seawater desalination (deionization), e.g.: DE000002650482A1, Evaporation by solar heat, DE202007012405U1, Distillation, Electric or solar energy, CN000211445106U, with evaporation, CN000208667184U, furthermore with membranes, CN000206278964U, by reverse osmosis, CN000112062233A, only partial recirculation of salt water, DE202021102883U1, using piping systems through electricity and / or magnetic fields, DE000004334317A1, electrochemical membrane process, DE3612188A1 Solar desalination plant with solar absorber and condenser, EP0970018B1, Solar desalination plant with evaporation basin and condensation surface, US20080078670A1, “Solar Still” with transparent roof and condensate collection, WO001998022203A1, series-connected electrodialysis.

[0010] My invention is based on the further development of seawater desalination through evaporation, in order to obtain fresh water in an energy-saving, cost-effective and simple way.

[0011] The existing solutions fulfill their function under the circumstances, but do not have the capabilities of the aforementioned invention.

[0012] The possibility of effective seawater desalination or deionization of water is desired, and the invention specified in claim 1 for the very rapid production of a low-tech plant using evaporation by solar heat fulfills these requirements. Examples of implementation:

[0013] Saltwater is pumped from the sea into large, shallow basins. The pumps and the supply and discharge pipes are located in Fig. 1 not shown. As shown in claim 1, the seawater desalination plant comprises an evaporation basin with seawater 1, which in a simple embodiment ( Fig.1) The bottom is lined with a black (e.g., pond) absorbent foil 2. According to claim 2, in this simple design, the edges are only raised (with stones, sand, etc.) or shallow basins are created. As described in claim 3, a transparent foil 3 is stretched over the evaporation basin, optionally with a tensioning system. The transparent foil serves as a condensation surface. The transparent foil is stretched over the basin and optionally has a support structure. According to claim 4, evaporated water 4 condenses on the underside of the transparent foil and drips onto the transparent, vapor-permeable, inclined middle foil 6 (e.g., like a very fine mesh, without harmful chemicals) and is collected on one side in a collecting channel 5. As described in claim 5, rainwater above the transparent foil is also drained into collecting channels.

[0014] Optionally, according to claim 6, drip traps 7 are installed, which can also serve as a support structure. As described in claim 7, fans 8 powered by solar cells / photovoltaics (power generation required depending on solar radiation and evaporation) or by wind / air movement with a wind guide can transport the moisture more effectively to the (horizontally or vertically installed) drip traps.

[0015] Optionally, according to protection claim 8, cooling by seawater can enhance condensation.

[0016] As described in claim 9, instead of the transparent condensation film, a glass or plastic cover can be installed over the basin.

[0017] Cleaning robots / an automatic cleaning system, which are charged wirelessly with solar cells, for example, keep the pools, foils and other structures of the facility clean according to protection claim 10.

[0018] If foils are used – as described in claim 11 – these can be lowered along with the support structure / posts in strong winds. Additionally, seawater can be directed onto the uppermost foil for weighting. In the simpler version, if no support structure is present, the foil(s) according to claim 12 will be lowered in windy conditions or similar and, if necessary, also weighted down with seawater.

[0019] As shown in claim 13, insulation is optionally installed below the black (absorber) foil.

[0020] Optionally, according to claim 14, salt water is finely dispersed, which is injected or atomized.

[0021] As described in claim 15, a portion of the surface can optionally be covered with a transparent film stretched across the center, serving as an additional drainage channel for condensation and functioning as additional collection channels. Steam can rise between the film sections.

[0022] In addition, according to protection claim 16, besides filters, grids, methods for removing algae (e.g. ozone, UV light, etc.), (e.g. UV) disinfection and other treatments for drinking water are also installed.

[0023] The inlet and outlet of the seawater desalination plant can – as described in claim 17 – consist of two large pipelines whose outlets must be sufficiently far apart to prevent the inlet from mixing with the higher salt concentration of the outlet. This is readily achievable, for example, if the pipeline outlets are also at different elevations. Furthermore, it is essential to ensure that the higher salt concentration of the outlet does not cause environmental damage to the underwater environment.

[0024] Deionization takes place according to claim 18 at normal ambient temperatures and pressure conditions (apart from the pressure generated by the pumps).

[0025] The pumps can – as described in claim 19 – obtain, for example, the necessary or supporting electricity from a photovoltaic system / solar cells next to the pools or from wind turbines.

[0026] A major advantage, as with other deionization methods, is that primarily, apart from pump components, there are no moving parts that require regular maintenance or can fail.

[0027] The systems are cost-effective, modular, scalable, energy-saving and particularly suitable for dry coastal regions. Reference symbol list 1 Seawater / ionized water 2 black absorber foils / thin black absorber plates 3 transparent film / glass or plastic cover 4 condensed freshwater 5 Collection trough for freshwater 6 vapor-permeable water-repellent film 7 drip catchers 8 Wind (- Guide) / Fan QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 000002650482A1

[0009] DE 202007012405U1

[0009] CN 000211445106U

[0009] CN 000208667184U

[0009] CN 000206278964U

[0009] CN 000112062233A

[0009] DE 202021102883U1

[0009] DE 000004334317A1

[0009] DE 3612188A1

[0009] EP 0970018B1

[0009] US 20080078670A1

[0009] WO 001998022203A1

[0009]

Claims

Seawater desalination or deionization of water by sunlight, characterized in that the seawater desalination plant comprises an evaporation basin with seawater, the bottom of which is lined with a black (e.g. pond) absorber foil. Seawater desalination or deionization of water by sunlight according to claim 1, characterized in that the edges of the basins are raised (with stones, sand or support structure) or shallow basins are created. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that a transparent film is stretched over the evaporation basin, optionally with a tensioning system. The transparent film optionally has a support structure. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that evaporated water condenses on the underside of the transparent film and drips onto the transparent, non-water-permeable but vapor-permeable, inclined middle film (e.g., like a very fine grid) and is collected on one side in a collecting trough. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that rainwater is diverted into the collection channels above the transparent film. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that droplet catchers are installed which can also serve as a support structure. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that additionally fans powered by solar cells / photovoltaics or by wind / air movement with a wind guide transport the moisture to the (horizontally or vertically installed) droplet collectors. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that cooling with seawater intensifies the condensation. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that a glass or plastic cover is installed over the basins instead of the transparent condensation film. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that an automatic cleaning system / cleaning robot, which is charged wirelessly with solar cells, for example, cleans the basins, foils and other structures of the plant. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that, in strong winds, the foils are lowered along with the support structure / posts. Additionally, seawater can be directed onto the uppermost foil for weighting. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that in the simple embodiment the foils are lowered in the wind and, if necessary, weighted down with seawater. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that insulation is installed below the black (absorber) film. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that the salt water is finely dispersed, i.e. injected or atomized. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that a portion of the surface in the center is covered with transparent films (additional drainage of condensate / additional collection channels). Steam rises between the film sections. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that, in addition to filters, grids, methods for removing algae and other seawater components (e.g. ozone, UV light, etc.), disinfection and other treatments for drinking water (e.g. UV) are also installed. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that the inlet and outlet of the seawater desalination plant consist of at least two large pipelines whose outlets are located far enough apart that the inlet is not mixed with the higher salt concentration of the outlet. This is achievable, for example, if the outlets of the pipelines are also at different elevations. Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that the deionization takes place at normal ambient temperatures and pressure conditions (apart from the pressure generated by the pumps). Seawater desalination or deionization of water by sunlight according to one of the preceding claims, characterized in that the pumps receive electricity from a photovoltaic system / solar cells or from wind turbines installed next to the basins.

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