Method of controlling progressive freeze-concentration

#Priority is claimed on Japanese Patent Application 2003-314975 filed Sep. 8, 2003.

#This invention relates to a method of controlling progressive freeze-concentration. The so-called freeze-concentration method is coming to be noted for concentrating target liquids of foods and medicaments for obtaining concentrates of a superior quality. Although both the suspension crystallization method and the progressive freeze-concentration method are known as examples of the freeze-concentration method, the present invention relates to the progressive freeze-concentration method and in particular to a control method for the progressive freeze-concentration of a target liquid while a target liquid and a cooling medium are being circulated.

#As disclosed, for example, in Shokuhin-To-Gijutsu (“Foods and Technologies”), Vol. 318, pp. 1–8 (December, 1997) and the Proceedings of Japan Society of Food Engineering ((2000), page 85), it has been known as a method of progressive freeze-concentration to freeze-concentrate a target liquid by causing a cooling medium to circulate through a cooling-medium flow route of a freeze-concentration apparatus while causing the target liquid to circulate through a target-liquid flow route of this apparatus so as to gradually form ice crystals on wall surfaces of the target-liquid flow route.

#FIG. 1 is a system diagram for showing a control method of this invention.

#FIG. 2 is a system diagram for showing another control method of this invention.

#FIG. 3 is a graph for showing the results of a freeze-concentration process controlled by a method according to this invention.

#FIG. 1 is a system diagram showing the method of control according to this invention. Two cylindrical double tubes 11 and 12 are provided, each having a target-liquid flow route 11a or 12a formed inside and a cooling-medium flow route 11b or 12b formed outside. The two target-liquid flow routes 11a and 12a are connected so as to together form a single circulating flow route 11c. A supply container 21 for the target liquid is disposed above the cylindrical double tubes 11 and 12 and is connected to the circulating flow route 11c. The two cooling-medium flow routes 11b and 12b are connected together at its upper and lower parts. An inlet and an outlet for the cooling medium are provided respectively at a lower part and an upper part of the cooling-medium flow route 12b. The inlet and the outlet are both connected to a cooler 31.

#A pump 41 for circulating the target liquid is provided to the circulating flow route 11c above the target-liquid flow route 11a. A flow-out tube 51 branches out of a connecting tube which connects a point on the circulating flow route 11c further above the pump 41 and the supply container 21. The tip part of the flow-out tube 51 is received in a receptacle 51a. Another pump 42 for circulating the cooling medium is provided between the inlet of the cooling medium into the cooling-medium flow route 12b and the cooler 31.

#A pressure sensor 61a is provided at the bottom of the receptacle 51a, a flowmeter 61b is inserted into the circulating flow route 11c above the target-liquid flow route 12a and a temperature sensor 61c is provided between the pump 42 and the inlet for the cooling medium into the cooling-medium flow route 12b. The pressure sensor 61a, the flowmeter 61b and the temperature sensor 61c are all connected to a calculation controller 71 which is also connected to the cooler 31 and the pump 41.