Patent attributes
In a method of controlling progressive freeze-concentration by circulating a cooling medium through a cooling-medium flow route while circulating a target liquid for freeze-concentration through a target-liquid flow route so as to gradually form ice crystals on wall surfaces of the target-liquid flow route, a volume expansion detecting device is used to detect volume expansion of the target liquid and thickness of the ice crystals in the target-liquid flow route is obtained from the volume expansion detected by this volume expansion detecting device. The flow rate of the target liquid and the growth speed of the ice front in the target-liquid flow route are controlled to become equal respectively to a set flow rate value and to a set growth speed value by carrying out operations of specified kinds based on the crystal thickness thus obtained such as calculating inner diameter of the ice crystals, calculating a required flow volume of the target liquid in the target-liquid flow route from the calculated inner diameter and the set flow rate, and adjusting circulation volume of the target liquid such that measured flow volume of the target liquid becomes equal to the required flow volume, and calculating actual growth speed of the ice front from the obtained crystal thickness and adjusting temperature and/or circulation volume of the cooling medium such that the calculated actual growth speed becomes equal to the set growth speed value.
