| 摘要 |
PURPOSE:To enable the type of products to be economically switched, by adopting a particular method in switching the type of products without stopping the operation in a process wherein polymers are continuously produced through vapor phase polymerization by making use of a vertical agitating fluidized bed. CONSTITUTION:The following method is adopted in switching the type of polymer without stopping a polymerization reaction within a vertical reaction tank equipped with an agitator in gas phase polymerization through an agitating fluidized bed system wherein a particle bed comprising a catalyst, a polymer, etc. is fluidized with a gas fed from the bottom of the reaction tank and, at the same time, agitated with the agitator. Specifically, the amount of polymer retained within the reaction tank is decreased to 0.25-0.45 time the agitating capacity (V) of the reaction tank. In this step, the reaction conditions other than the amount of polymer retained within the reaction tank are changed. After the amount of polymer retained within the reaction tank has been decreased to a predetermined value, the discharge of the polymer is stopped. The discharge of the polymer is restarted after the amt. of polymer retained within the reaction tank is restored to at least 2.5 times the value of the above- described predetermined amt. of decrease. The term 'agitating capacity' is intended to mean an internal volume of the vertical agitating tank in the part from the bottom of the tank to the top of the agitating blade.
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