JPH05345181

PURPOSE:To attempt to make exchange rate of a membrane proper assuming that a guaranteed quality of water is ensured in the operation of a reverse osmosis type sea water desalination apparatus. CONSTITUTION:Electrical conductivity of permeated water through a unit reverse osmosis membrane 1F is measured by means of a conductivity meter on an instrument rack through a sampling rack 101 and it is input into a personal computer control apparatus 107 by means of a field operation panel 105. Operating condition of a plant is also input and the electric conductivity is corrected to obtain individual data and an average value and a standard deviation of these data. Pressure densifying factor and membrane deterioration rate factor are obtd. from these data and the membrane exchange rate is obtd. in such a way that the estimated quality of water after exchanging of the membrane does not violate a guaranteed value as the time elapses assuming that exchanging of the membrane is performed at a specified rate every year. Therefore, a proper exchange rate of the membrane can efficiently be set on every reverse osmosis membrane type sea water desalination apparatus and exchanging of the membrane can reasonably be performed and decrease in expenditure of maintenance and control is attainable.