WATER DESALINATION DEVICE, AND WATER DESALINATION METHOD

摘要

Disclosed is a water desalination device provided with a first reverse osmosis membrane device (13) for removing salt from raw water (11) supplied at a given pressure, a second reverse osmosis membrane device (15) for removing salt within a first permeated water (12) supplied from the first reverse osmosis membrane device (13), a first flow regulating valve (17) for regulating the flow of a first concentrated water (16) supplied from the first reverse osmosis membrane device (13), and a second flow regulating valve (19) for regulating the flow of a second concentrated water (18) supplied from the second reverse osmosis membrane device (15), wherein the supply temperature of the aforementioned raw water (11) is measured with a thermometer (20), and when the temperature of the raw water (11) is determined to be low, such as during winter, an adjustment for maintaining the amount of concentrated water being discharged at the first flow regulating valve (17) at constant, and an adjustment for reducing the amount of water taken out at the second flow regulating valve (19) are performed, and while an adjustment to reduce the supply flow volume to the first reverse osmosis membrane device (13) with regard to the supply flow volume when the temperature is high, such as during summer, is performed, an operation for maintaining a given recovery rate for the product water at a predetermined amount is performed.