| 摘要 |
PROBLEM TO BE SOLVED: To restrain the increase of internal pressure of a tank for a tank container carrying a low temperature liquefied gas with the gas inside the tank cooled and reliquefied and to realize a long-hour transportation without requiring a vent station by a method wherein an agitator for taking the gas in a gas layer into a liquid layer for mixing in the tank is provided. SOLUTION: At the same time with a start of transportation by a tank container 1, a motor 11 for driving an agitator 5 is started. Then, a gas in a gas layer 3 is brought for mixing into a low temperature liquefied gas in a liquid layer 4 and cooled down by vibrations of a tank 2 resulting from travelling of a tank lorry and rotation of a middle impeller 7 and at the same time, the gas is partly reliquefied. Thereby, the increase of internal pressure inside the tank 2 is restrained. Furthermore, the gas in the gas layer 3 is circulated by operation of an upper impeller 6, and a high temperature gas staying in the upper part of the gas layer 3 is sent toward the liquid layer 4. A low temperature liquefied gas in the liquid layer 4 is also circulated by operation of a lower impeller 8 and a low temperature gas staying at the lower part of the liquid layer 4 is sent to the point of mixing.
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