Apparatus for the production of fresh water from sea water by reverse osmosis

Apparatus for the production of fresh water from seawater, adapted to be immersed into the marine medium, of the type comprising:

• means for collecting fresh water produced (9),
• a chamber (1), called a high pressure chamber, adapted to contain seawater preparatory to its treatment,
• at least one selective semi-permeable membrane (11) adapted to carry out a filtration by reverse osmosis of the seawater contained in the high pressure chamber, said membrane being arranged in such a manner that one of its faces, termed the upstream active face, communicates with said high pressure chamber and the other active face, termed the downstream active face, communicates with the fresh water collecting means,
• a bell chamber (14) movable with respect to the high pressure chamber comprising:
• on one part, a peripheral wall adapted to be displaced lengthwise along the high pressure chamber,
• on the other part, an internal piston having a working surface (s) able to penetrate to a variable depth in the high pressure chamber across a separation wall (3) situated between the said chamber and said bell chamber,
• a closing wall (16) having a working surface (S) situated opposite the working surface (s) of the piston and subject to pressure of the exterior medium, said working surface (S) of the closing wall being of greater size than said working surface of the piston,
• a subatmospheric gas chamber (26) situated in the interior volume of the bell chamber around the internal piston thereof,
• said separation wall (3) of the high pressure chamber (1) further comprising communication means (12, 3b) connected to the semi-permeable membrane (11) for bringing the downstream active face of said membrane into communication with the interior volume of the bell chamber (14) in such a manner that said interior volume fulfills the dual role of sub-atmospheric gas chamber (26) and fresh water recovering means (9), the bell chamber (14) being provided with means (23) for receiving the fresh water contained in its interior volume.