To recover in an LNG storage tank, drain generated by mist entrapped in the BOG tube of the LNG storage tank, by interposing opening/closing valves respectively in a drain recovering tube for extracting drain in the BOG tube and a drain expelling BOG supply tube.
After the opening/closing valve 14 of a drain expelling tube 15 is opened, the opening/closing valves 11, 12 of a drain recovering tube 10 and a communicating tube 20 are opened. Further, when the opening/closing valve 19 of a BOG supply tube 17 is closed, pressure in a drain pot 12 is retained equal to the internal pressure of an LNG storage tank 1. Also, drain entrapped in a BOG tube 2 is pooled in the drain pot 12. When the drain reaches a predetermined level, the opening/closing valves 11, 21 of the drain recovering tube 10 and the communicating tube 20 are closed, and the opening/closing valve 19 of the BOG supply tube 17 is opened. Then, high pressure BOG is introduced from the BOG supply tube 17 to the inside of the drain pot 2, and internal drain is pushed out to the drain expelling tube 15. As a result, drain in the drain pot 12 is recovered from the drain expelling tube 15 to the LNG storage tank 1.
TAKAGI SHINICHI
KUNO YASUSHI
SOMEYA MASAYUKI
CHIYODA CHEM ENG CONSTRUCT CO