Patent EA-000617-B1 (EA)
Title: Water desalination plant and method thereof
Inventor: GRAHAM WILLIAM
IPC: B01D61/06
Filed: 1996-12-13
Abstract: 1. A reverse osmosis desalination plant which comprises a filter element consisting of reverse osmosis membranes defining salt passages, a pump for pumping water to be desalinated to said filter element, and an obstruction in the water flow path between said pump and said filter element for introducing turbulence into the flowing water and causing a pressure drop across the obstruction whereby said obstruction has a plurality of holes in it for flow water pass of different area. 2. A desalination plant as claimed in Claim 1, wherein said obstruction is in the form of a plate with a plurality of holes in it whereby the flowing water is obstructed and divided up into a number of turbulent water streams each of which is at a lower pressure than the pressure of the water upstream of the plate. 3. A desalination plant as claimed in Claim 2, wherein a series of flow restricting valves is provided for varying the flow areas of the holes in the plate, which create the individual water streams. 4. A desalination plant as claimed in Claim 2 or 3, and including a cylindrical casing, said filter element being within said casing and fabricated such -that the entrances to the salt passages are at one end of the filter element, a disc constituting said plate, said disc being between one end of the casing and said filter element and being spaced from said one end of the filter element and an inlet for water to be desalinated at said one end of the casing, the water which in use enters the casing through said inlet flowing through the holes in the disc, being broken up into a plurality of diverging water streams, and impinging on said one end of the filter element. 5. A desalination plant as claimed in Claim 2 or 3 and including a cylindrical casing, said filter element being within said casing and fabricated such that the entrances to the salt passages are at one end of the filter element, a disc constituting said plate, said disc being between one end of the casing and said filter element and being spaced from said one end of the filter element, there being in said cylinder a pump and a motor for driving the pump, the pump being between said disc and said one end of the casing and serving to pump water to be desalinated through the holes in the disc to break it up into a plurality of diverging water streams which impinge on said one end of the filter element. 6. A desalination plant as claimed in Claim 5, and including a filter for removing solid material from the water to be desalinated, the filter being between said pump and said disc. 7. A desalination plant as claimed in Claim 6, wherein said pump has an outlet with two branches, the first branch leading through the filter to a chamber one boundary of which is constituted by said disc, water normally flowing through said one branch, through the filter to said chamber and then through the holes in the disc, and the other branch bypassing the filter and leading directly to said chamber, there being a normally closed outlet communication with the core of the filter, said outlet, when opened, permitting back-washing water to flow from said chamber through said filter in the reverse direction and out through said outlet. 8. A desalination plant as claimed in Claim 2, 3 or 4, and including a housing with at least one buoyancy space for enabling the housing to float, said cylindrical casing with said filter element and disc therein being within said housing and said pump in use delivering sea water under pressure to said casing. 9. A desalination plant as claimed in Claim 8, wherein said housing is vertically elongate and has a horizontal partition separating a water intake chamber below the partition from a buoyancy space above the- partition, said housing having holes therein to permit sea water to flow into said water intake chamber, said pump in use withdrawing sea water from said chamber and delivering it to said casing which is in the buoyancy space. 10. A desalination plant as claimed in any one of Claims 4 to 9 and which includes means for subjecting recovered water to ultraviolet light. 11. A desalination plant as claimed in any one of Claims 1 to 4, wherein said pump is a ram pump. 12. A desalination plant as claimed in any one of Claims 1 to 4, wherein said pump is a manually operable piston pump for delivering water under pressure to the filter element. 13. A desalination plant as claimed in any preceding Claim and including means for utilizing the pressure-based energy available in the brine, which emerges from the salt passages to supplement the power source of said pump. 14. A desalination plant as claimed in Claim 1, 2, 3 or 4, and including an outlet through which recovered water flows from the filter element, an auxiliary pump having its suction inlet connected to said outlet for recovered water, a hollow column extending upwardly from said auxiliary pump and connected to the pressure outlet of the auxiliary pump, a brine outlet from said filter element, and a drive motor connected to said brine outlet so that, in use, brine under pressure flows through said motor and drives it, said motor being connected to said auxiliary pump so as to drive the auxiliary pump. 15. A desalination plant as claimed in Claim 14, wherein said drive motor is a Pelton wheel. 16. A method of desalinating water which comprises pumping water to be desalinated to a filter element consisting of reverse osmosis membranes defining salt passages, causing a pressure drop in the water flowing to the filter element and simultaneously introducing turbulence into the water flow, and feeding the turbulent water via said obstruction, whereby the water flow is passed through a plurality of holes of different area. 17. A desalination method as claimed in Claim 16, wherein the water is divided into a plurality of turbulent, conically shaped, diverging water streams. 18. A desalination method as claimed in Claim 16 or 17, and including feeding sea water through a reverse osmosis membrane to produce an auxiliary supply of water substantially devoid of dissolved solids, mixing this water with sea water, and delivering the diluted sea water to said filter element. 19. A method as claimed in Claim 16, 17 or 18 and including adding a quantity of brine to the desalinated, recovered water to vary the mineral balance of the recovered water. 20. A method as claimed in any one of Claims 16 to 19, wherein the water is initially at a pressure of 50 to 65 Bar and the pressure drop is between 1.5 and 2.0 Bar.