Reverse osmosis treatment system for recovering energy generated both at brine and permeate sides during seawater desalination
Provided is a reverse osmosis treatment system capable of simultaneously and efficiently recovering energy generated both at brine and permeate sides. The system comprises a branched portion configured to divide second to-be-treated water into third and fourth to-be-treated water; a high-pressure pump configured to pressurize the third to-be-treated water thereby to feed fifth to-be-treated water having a higher pressure than the to-be-treated water before divided; a displacement type of first energy recovery device configured to exchange pressures between the fourth to-be-treated water and brine thus separated by a reverse osmosis treatment device, thereby to produce sixth to-be-treated water having a higher pressure than the fourth one; and a second energy recovery device configured to raise a pressure of the third to-be-treated water located at a downstream side of the branched portion with a pressure of first permeate thus separated by the reverse osmosis treatment device.
1. A reverse osmosis treatment system comprising:
a reverse osmosis treatment device configured to separate first to-be-treated water into permeate and brine via reverse osmosis;
a branched portion at which second to-be-treated water is divided into third to-be-treated water and fourth to-be-treated water;
a first pump configured to pressurize the third to-be-treated water thus divided, thereby to feed fifth to-be-treated water having a higher pressure than to-be-treated water before divided into the third to-be-treated water;
a first energy recovery device configured to exchange pressures between the fourth to-be-treated water thus divided and the brine thus separated by the reverse osmosis treatment device, thereby to produce sixth to-be-treated water having a higher pressure than the fourth to-be-treated water;
a merging portion at which the fifth to-be-treated water and the sixth to-be-treated water are merged to produce the first to-be-treated water; and
a second energy recovery device configured to raise a pressure of the third to-be-treated water located at a downstream side of the branched portion with a pressure of the permeate thus separated by the reverse osmosis treatment device.
2. The reverse osmosis treatment system described in claim 1 , wherein the second energy recovery device is configured to raise the pressure of the third to-be-treated water located at the downstream side of the branched portion by rotating a turbine or a Pelton wheel with a pressure of the permeate.
3. The reverse osmosis treatment system described in claim 2 , wherein the second energy recovery device is configured to raise a pressure of the third to-be-treated water before being fed by the first pump.
4. The reverse osmosis treatment system described in claim 1 , wherein the second energy recovery device is configured to raise a pressure of the third to-be-treated water before being merged at the merging portion.
5. The reverse osmosis treatment system described in claim 1 , wherein
the first pump includes a motor configured to drive a rotor of the pump,
the second energy recovery device includes a turbine or a Pelton wheel fixed on an axis of the motor, and
the turbine or the Pelton wheel is rotated with a pressure of the permeate.