As the seawater is supplied on offering/accompanying water supply side of power recovery manner and the device

摘要

PROBLEM TO BE SOLVED: To enhance the recovery ratio of energy on a conc. water side recovered by a power recovery turbine to a large extent while keeping a predetermined constant fresh water making ratio with respect to the supply amt. of seawater. SOLUTION: In the power recovery device in a reverse osmosis membrane type seawater desalting apparatus, seawater is supplied to the supply water side of a reverse osmosis membrane 1 by a water supply pump and fresh water is taken out of the reverse osmosis membrane 1 on the permeating water side thereof and a power recovery turbine 14 is provided on the conc. water side of the reverse osmosis membrane 1 to recover the energy possessed by conc. water. In this case, the pressure of the conc. water side is controlled to high pressure of a constant level or more within the range capable of being taken by the pressure on the conc. water side by controlling the flow rate on the permeating water side.