LIQUID LEVEL CONTROL METHOD OF ION EXCHANGE RESIN COLUMN, ITS LIQUID LEVEL CONTROL SYSTEM AND INTERFACE LEVEL SENSOR

摘要

A liquid surface level control method for an ion-exchange resin tower according to the present invention comprises steps of determining an operation signal (S18, S28, S38) of a discharge device of liquid (6) to be discharged from the ion-exchange resin tower (2a, 2b, 2c), based on a liquid surface level PID operation signal obtained by calculating a liquid surface level signal (S12) in a PID way and a supply flow rate signal (S10, S18, S28) supplied to the ion-exchange resin tower (2a, 2b, 2c), and moving the liquid surface level (6a) close to the target liquid surface level. Preferably, the interface level (4a) is detected by means of an interface level sensor (52), and the target liquid surface level is increased or decreased according to the increase/decrease of the interface level (4a). The interface level sensor (52) includes a plurality of light emitting parts and a plurality of light receiving parts which are opposite to each other in a one-to-one relation.