Cage frame type final polycondensation reactor and method for producing polyester

Abstract

The invention discloses a cage frame type final polycondensation reactor and a method for producing polyester. The cage frame type final polycondensation reactor comprises a cylinder body and a cage frame stirrer arranged in the cylinder body. The cage frame stirrer comprises a cage frame and two disc chucks arranged oppositely, and a rigid supporting piece is connected between the two disc chucks. The rigid supporting piece is fixed to the cage frame and used for driving the cage frame to rotate and draw a film, and the disc chuck on at least one end is connected with a driving device for driving the cage frame to rotate. The invention also discloses a method for producing polyester. The cage frame, the rigid supporting piece and a concave groove are matched, so that the stirring flexibility is small, the weight is light, the size is small, and the stirring efficiency is high. A rotating shaft is not needed, the rigid supporting piece replaces the rotating shaft in a traditional cage frame stirrer, the situation in which high-viscosity melt is a adhered to the disc chucks and a shaft can be effectively reduced, and the size and the weight of the device are reduced.

Description

technical field [0001] The invention relates to a reactor and a method for producing polyester, in particular to a cage-type final polycondensation reactor and a method for producing polyester. Background technique [0002] At present, PET melt polymerization reactors generally adopt two stirring forms. One is the five-pot process technology improved by the German Zimmer Company in the 1980s. The final polycondensation reactor of this technology uses a solid shaft disc to stir, and is mainly used for the production of fiber-grade PET. The intrinsic viscosity is generally controlled at 0.690dL / g . The second is the three-pot process technology improved by DuPont Company of the United States in the 1990s. The final polycondensation reactor of this technology adopts hollow shaft cage frame stirring (squirrel cage stirring). Due to the small size, low energy consumption and high efficiency of the squirrel cage melt polycondensation reactor, it has obvious advantages over the d...

AI Technical Summary

Problems solved by technology

However, compared with discs, the film-forming efficiency in the low-viscosity section of the squirrel cage is poor, and the viscosity of the polyester melt entering the final polycondensation reactor for pre-condensation is generally between 0.25-0.30dL / g, and the dynamic viscosity is low. The film cannot be formed effectively. Generally, equipment manufacturers adopt the method of dense at the beginning and thin at the end to solve the problem of low film forming efficiency in the low-viscosity section. However, the squirrel cage is generally designed with a hollow shaft, which is used to prepare high-viscosity polyester 0.75dL / g high-viscosity polyester When the melt is melted, the dynamic viscosity of the polyester melt before and after the difference is more than 100 times, and the radius before and after stirring is relatively large, which is very easy to damage the stirrer, which is similar to twisting and twisting.

At present, the existing squirrel cage / cage frame stirrer can produce PET with an intrinsic viscosity of up to 0.74dL / g, but at this time there is an abnormal sound inside the reactor, and it cannot be produced stably for a long time

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