Seawater, brine or sewage solar desalination plant, and desalination method

Abstract

A tent or covering with a pyramid-shaped structure, with an inner dark-colored sheet and an outer transparent sheet, installed on a supporting base anchored to the ground or on floats on the surface of the sea, wherein in the apex of the pyramid there are included vaporizers with micronebulizers for nebulizing the water to be treated, a device for capturing humid air through a continuous or sectioned condensation column and for subsoil distillation and heat dissipation in the smaller, water-collecting tank and recirculation of the air devoid of humidity into the enclosure. In addition, it includes a computerized control system of the processes includes controls of the air and nebulized water flow rates and of the working regime of the facility.

Claims

1. A seawater, brine or sewage solar desalination plant comprising a fresh-water collecting tank in the subsoil or below sea level, and a closed enclosure bounded by a transparent shell installed on a supporting base anchored to the ground or on floats on the surface of the sea, said closed enclosure comprising: a dome, triangular cupola or pyramidal upper area; a solar collector placed inside the closed enclosure, associated with said transparent shell and separated therefrom comprising a sunlight-capturing surface with a dark finish placed inside the closed enclosure for generating hot air by solar energy, said sunlight-capturing surface with a dark finish being parallel to the outer transparent shell and spaced therefrom, providing an ascending sloped interspace, open at a low level, near said supporting base and open at an upper part so that sunlight is captured and transformed into heat that will warm the air of the interspace carrying hot air towards said upper area and concentrating there; vaporizing means including a number of micro nebulizers of the water to be treated in the upper area of the closed enclosure, providing nebulized water where the hottest air is accumulated; at least a vertical condensation and distillation column; a sucking device for collecting humid air, resulting from the nebulized water evaporation, drawing off the humid air towards an inlet area of said at least a vertical condensation and distillation column, said inlet area being placed in said upper area so that the humid air is pushed down said at least a condensation and distillation column that is communicated with said fresh-water collecting tank wherein a water condensation and a heat dissipation are completed, and air recirculation tubes for recirculating the collected humid air, discharged of water, from said fresh-water collecting tank towards the interior of the closed enclosure; and wherein the supporting base accumulate salt crystals produced due the evaporation of the water nebulized in the upper area of the closed enclosure and fall by gravity.

2. A desalination plant according to claim 1 wherein: at least one conduit for the water to be treated, is supported on said at least a condensation and distillation column; said vaporizing means include several nozzles for micro nebulizing the water to be treated towards said upper area where the heated air is accumulated; and a pump connected to said at last one conduit for pumping the water to be treated towards said nozzles.

3. A desalination plant according to claim 2 wherein at least one stretch of the conduit for water to be treated is in interference with the high-temperature humid air capturing conduit next to the column upper end area, then absorbing a latent condensing heat in the air of said upper end area.

4. A desalination plant according to claim 1 wherein said fresh-water collecting tank remains inside a larger tank intended for the provision or supply of the recovered usable fresh water, located at a lower level, with a selective communication from one tank to the other by a controlled valve or drip cock wherein said larger tank provides a low temperature and cooling off during night.

5. A desalination plant according to claim 4 wherein said fresh-water collecting tank comprises several branches extending under the base of the enclosure, branches from which a communication is established for the return of air deprived of humidity towards the interior of the enclosure by the tubes.

6. A desalination plant according to claim 5 wherein said fresh-water collecting tank is in communication with the outside through at least one conduit for feeding refreshment air from the outside at a time selected by an adequate outside environment temperature.

7. A desalination plant according to claim 1 wherein said enclosure has a quadrangular pyramidal configuration including one single column or a configuration with at least one upper portion forming an elongated triangular cupola including several columns spaced apart and each of them ending close to said upper portion.

8. A desalination plant according to claim 1 including a computerized processing control system comprising controls of the flow rates of the air and the nebulized water to be treated and of the working regime of the facility.

9. A desalination plant according to claim 4 wherein said collecting fresh-water tank and the larger tank are arranged at some depth under the condensation column.

10. A desalination plant according to claim 9 wherein the larger collecting tank is in communication and contact with subsoil tunnels for heat dissipation.

11. A desalination plant according to claim 1 wherein a salt collection and accumulation area has been provided next to the base of the at least a column and in that the remainder of the bounded space under the transparent covering is useful as a dwelling or for agricultural purposes with a controllable microclimate.

12. A desalination plant according to claim 11 wherein at least one entrance and at least one passage to the interior of enclosure have been provided for the removal of usable salt, built up at the base of the at least a column.

Description

DESCRIPTION OF THE DRAWINGS

(1) In order to complement the description being made of the mechanism subject of the invention and in order to further a better comprehension of the characteristics that distinguish it, the present descriptive specification is accompanied, as an integral part thereof, by a plan in which the following is represented with an illustrative, non-limiting nature:

(2) FIG. 1 shows a schematic representation of an exemplary embodiment of the seawater, brine or sewage solar desalination plant subject of the invention wherein the elements it comprises and the system operation are appreciated, arrows representing therefor the circulation movements of the water and the air.

(3) FIG. 2 shows a schematic representation of an exemplary embodiment of the seawater including some additional features not shown in FIG. 1.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT OF THE INVENTION

(4) In view of the described and solitary FIG. 1, and in agreement with the numbering adopted for it, the parts and elements that the desalination plant of the invention comprises can be appreciated, and the operation process thereof can be understood.

(5) The plant comprises: an enveloping structure bounding a closed enclosure 1, in the illustrated example in the shape of a pyramidal tent with an inner dark-coloured sheet (in order to keep the maximum amount of heat) and an outer transparent surface or sheet 2, arranged parallel to the former, so that in the interspace being defined between said two surfaces a layer of heated air that ascends towards the top of the structure will be generated by solar energy; a vertical column 3 that ends in a region near said top of the enclosure; a conduit A that provides the water to be treated and that is supported on said column 3; nozzles 6 for micronebulising the water to be treated, which is pumped through said conduit A towards said build-up area of heated air, producing the vaporisation of water and the evacuation of salt crystals that fall by gravity at the base of column 3, where they accumulate; pumping equipment for the water to be treated that circulates along conduit A towards said nozzles 6; a conduit, axial to said column 3, for the capture of humid air through a sucking device C located close to the apex of column 3, in an inlet area to the axial conduit; a collecting tank 4 for the condensed liquid connected to said humid air-capture column; and air-recirculation tubes 5 from said condensed liquid tank 4 to the interior of enclosure 1.

(6) One characteristic of the plant resides in the fact that a stretch of the conduit (A) providing the water to be treated interferes with the high-temperature, humid air-capture conduit next to the topmost area in the column, whereby the provided water that is to be nebulised heats up, thereby favouring the evaporation process.

(7) In addition, the facility comprises a fresh-water collecting tank 7, which, arranged at a certain depth, for instance underground or submerged underwater at sea, under the condensation column 3, provides a low temperature to the generally smaller tank 4, which is located inside it to allow for condensation. This collecting tank 7 cools off during the night to allow for the evacuation of the heat accumulated during the day in case the system is located on the ground; not so in the case of a floating structure. To that end, the communication of said tank 7 with the exterior is contemplated at a time when its temperature is adequate. In addition, the tank 7 can be connected to tunnels 7a with a system that will make the temperature uniform and allow for good heat dispersion into the subsoil, as well as serving as a cistern to accumulate water at the times of maximum production to be used at the times of maximum consumption.

(8) If the plant is installed at sea, the low temperature of the collecting tank is ensured, since the temperature of the seawater at certain depth is always lower than that of the surroundings (in extreme conditions of isolation).

(9) The FIGURE shows a drip cock 8 incorporated into the smaller tank 4 in order to discharge the latter into the tank 7, since it is turned off so as to allow the circulation of air with one single impeller. As water accumulates in said smaller tank 4, it discharges in the collecting tank 7, which is the one storing the water produced and must provide the necessary frigories to the system.

(10) The least content of the tank 7 that must be kept to ensure this task and the cooling that must be provided at night-time for it to be able to carry out its condensing job on the next day are calculated. In addition, it acts as a cistern.

(11) Said collecting tank 7 is in communication with the outside through at least one conduit 5a for feeding refreshment air from the outside at a time selected by an adequate outside environment temperature.

(12) According to an embodiment shown on FIG. 2 said smaller tank 4 comprises several branches 4a extending under the base of the closed enclosure, branches 4a from which a communication is established for the return of air deprived of humidity towards the interior of the enclosure by the tubes 5.

(13) A supporting base 9 or installation area is the place where the plant is located and may be either on the ground or on floats on the surface of the seabroken line, as well as on the roof of a house, since the weight is not heavy.

(14) The salt collection area 10 that, in the example portrayed, is located in the lower central region of the pyramidal structure 1, is the place where non vaporised water and salt fall as a result of the NaCl molecule being heavier than that of water. At least one entrance 10a and at least one passage to the interior of enclosure 1 are provided for the removal of usable salt, built up at the base of column or columns 3.

(15) On the other hand, the remainder of the bounded space under the transparent covering 2 is useful as a dwelling or for agricultural ends, with a controllable microclimate.

(16) So, the operation of the plant, as already pointed out above, is as follows:

(17) First of all, the seawater (A) to be desalted is injected through a number of micronebulisers 6 provided on top of the condensation column 3, using saturated air collected near the apex to lead it through the condensation column conduit to the lower part of the tent with a pyramid-shaped structure 1.

(18) The apex or topmost part of said pyramidal structure 1 takes in less dense air, which is mostly that loaded with humidity, since, the greater the load of humidity of the air is, the less dense it will be. From here it takes the air that will go through the condensation column 3, which draws it in at its top and leads it towards the smaller tank 4, which is a cold spot and where the collecting tank 7 is located, wherein the water is discharged through the drip cock, and the remaining calories through diffusion. The condensation in the column can be sectioned so as to better retrieve the latent heat of condensation.

(19) Along the path of the seawater that is to be blown in, it has gone through a vertical tube inside the condensation column 3 that transports the air-vapour mixture countercurrent, thereby permitting the condensation in the form of fresh water through a heat exchanger: humid air-seawater.

(20) In turn, the partially cooled off air and part of its condensed water load reach the smaller tank 4 (coldest point of the entire process).

(21) The maximum condensation of the contained water occurs in this point. The air returns to the top, where it progressively heats up while, at the same time, it favours the condensation of the humid air circulating in the opposite direction along a stretch, also with a heat exchanger and countercurrent once again.

(22) The air 5 circulating through the pipes reaches the point where it is once again input into the system at the base of the pyramid, which normally coincides with the support base 9, where it can cooperate in the drying up of the remaining salt water that was not vaporised when it exited the micronebulisers 6; it is heated up with the solar radiation and contributes once again to the vaporisation of water, thus closing the circuit of air.

(23) The invention also contemplates the incorporation of a computerised process control (not shown) comprising: the air and nebulised water flow rate controls and the working regime of the facility.

(24) Thus, the invention provides a method for a seawater, brine or sewage solar desalination method characterised by carrying out one vaporisation step of the water to be treated by microspraying said fluid in a high area of a closed enclosure bounded by a transparent shell, wherein hot air generated by solar energy accumulates, and going on to capture the humid air resulting from the vaporisation in said area and transport it towards a vertical condensation and distillation column (3), completing the condensation and heat dissipation in at least one tank (4, 7) installed in the subsoil or below sea level, and recirculating the captured humid air, discharged of water, towards the interior of the enclosure.

(25) The provision of hot air towards the top of the enclosure, where vaporisation occurs, is carried out by means of a solar collector associated with said transparent shell, and separated therefrom, that provides an ascending sloped interspace.