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

摘要

A liquid level control system and a liquid level control method of an ion exchange resin column in which processing time can be shortened. A sensor for detecting the interface level between liquid and ion exchange resin is also provided. In the liquid level control method of an ion exchange resin column, operation signals (S18, S28, S38) of a device for discharging liquid (6) from ion exchange resin columns (2a, 2b, 2c) are determined based on a liquid level PID operation signal obtained by performing PID operation on a liquid level signal (S12), and supply flow rate signals (S10, S18, S28) of liquid supplied to the ion exchange resin columns (2a, 2b, 2c), and a liquid level (6a) is brought close to a target liquid level. An interface level (4a) is detected by an interface level sensor (52) and the target liquid level is preferably increased/decreased depending on increase/decrease of the interface level (4a). The interface level sensor (52) has a plurality of opposing light projecting portions and light receiving portions.