Is located to the ice plug formation device null

摘要

PROBLEM TO BE SOLVED: To reduce a consumption rate of liquid nytrogen, and form an ice plug for a short time by arranging a precooler, a cooling device and a temperature monitoring device, and driving the precooler so as to keep an inner temperature of a vertical pipe sensed by the monitoring device be a specified value. ;SOLUTION: Water inside a branch pipe 3 on which a cooling jacket 51 is arranged is cooled to 4°C by a precooler 50. Natural convection current is generated as indicated by an arrow between the vertical branch pipe 3 and a main pipe 1. Ascending current is stopped at an indicated portion. The water shows maximum specific gravity at 4°C. Water inside the branch pipe 3 is cooled by a cooling device 10 which is parallel and is retarded in starting the the extend that a sufficiently strong ice plug is generated. An inner temperature near the ice plug formation portion is monitored by a temperature monitoring device 57 using a thermo couple. When the temperature exceeds 4°C, starting command for the precooler 50 is sent to an operator.;COPYRIGHT: (C)1998,JPO