| 摘要 |
PROBLEM TO BE SOLVED: To prevent the lead of an air into a polycondensation reaction tank perfectly by blowing an inert gas with a specific pressure and amount to a gland part at the sealing time of the bearing part of a stirring device by a gland packing, in the polycondensation reaction device for carrying out the polycondensation reaction under a reduced pressure and stiring. SOLUTION: In the stirring device of a polycondensation reaction device for producing polyester by polycondensation reacting while stiring a polyester low polymer reacted dicarboxylic acid or ester forming derivative with glycol under a high temperature and high reduced pressure, when the bearing part of the stiring device is sealed by a gland packing 3, the inert gas is blown to the gland part through a lantern ring 6 from the inert gas blow in pipe 7, at the sealing time of the bearing stiring device by the gland packing 3. In other words, the inert gas with a pressure of 10mmAq or more, favorably 100∼400mmAq and an amount of 1∼300Nl/h, favorably 40-800Nl/h is blown to the gland part. Thereby, the leak of the air into the polycondensation reaction tank during reducing a pressure is perfectly prevented.
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