One-way pressure exchange device for reverse osmosis desalination plants

One-way pressure exchange device (1) for desalination plants by reverse osmosis, of the type comprising, at least, a pair of discharge loops (2,3) for the circulation of the entering low-pressure seawater flow in contact with another entering flow of high-pressure reject brine, for the transmission of the pressure differential of the entering reject brine to the entering seawater, prior to discharge to the RO desalination membranes (100);

• characterized by comprising:
• A first selecting valve (11) providing alternative entrance to the discharge loops (2,3), said first selecting valve (11) includes an outlet port connected to the inlet (4) of every pair of discharge loops (2,3) and an inlet port connected to the inlet of a collector (5) of high-pressure reject brine coming from the RO membranes (100),
• A second selecting valve (12) with alternative entrance from the discharge loops (2,3), said second selecting valve (12) includes an inlet port connected to the outlet (40) of every pair of d discharge loops (2,3) and an outlet port connected to the outlet of the collector (6) of low-pressure reject brine to evacuate it to the sea,
• A first unidirectional non-return valve (21) having an inlet port connected to the low-pressure seawater inlet (7), and an outlet port connected to the inlet (4) of the first discharge loop (2), providing circulation of low-pressure seawater directly from the seawater inlet (7) towards the first discharge loop (2),
• A second unidirectional non-return valve (22) having an inlet port connected to the low-pressure seawater inlet (7), and an outlet port connected to the inlet (4) of the second discharge loop (3), providing circulation of low-pressure seawater directly from the seawater inlet (7) towards the second discharge loop (3),
• A third unidirectional non-return valve (23) having an inlet port connected to the end of the first discharge loop (2) and an outlet port connected to a by-pass line (8) of high-pressure seawater to the inlet of the RO membranes (100), providing circulation of high-pressure seawater directly from the first loop (2) towards the by-pass (8) of high-pressure seawater at the inlet of the RO membranes (100),
• A fourth unidirectional non-return valve (24) having an inlet port connected to the end of the second discharge loop (3) and an outlet port connected to said to a-by-pass line (8) of high-pressure seawater to the inlet of the RO membranes (100), providing circulation of high-pressure seawater directly from the second loop (3) towards the RO membranes (100), and,
• Where the phases of the first selecting valve (11) and of the second selecting valve (12) are suited in a crossed manner.