| 摘要 |
PURPOSE:To perform concentration even when the amt. of a liq. to be treated is small and to continuously and stably recover a liq. concentrate of a specified concn. by adjusting the circulating flow rate and discharge flow rate of the concentrate to keep the temp. and concn. of a supply liq. in an equilibrium. CONSTITUTION:A back-pressure valve 32 on the discharge side is fully closed at first, the opening of a back-pressure valve 46 on the circulation side is adjusted to control the pressure of the supply liq. on the inlet side of a reverse-osmosis membrane module 24 to a prescribed value. When the temp. and concn. of the supply liq. are increased and kept in a transient state proceeding to an equilibrium, the back-pressure valve 46 on the circulation side is throttled and the back-pressure valve 32 on the discharge side is opened to decrease the circulating flow rate of the concentrate and to increase the discharge flow rate, and the pressure of the supply liq. on the inlet side is kept at a prescribed value. When the indicated value of a permeated liq. flowmeter 36 reaches a desired value, the opening of the back-pressure valve 32 on the discharge side is adjusted so that the indicated value of the flowmeter 34 of the concentrate on the discharge side is also controlled to a desired value. Thereafter, the concn. and temp. of the supply liq. are rapidly brought to an equilibrium, and the concn. of the concentrate leaving the module 24 is also made constant. |
