Method for Thermally Treating Polyester Pellets to Obtain a Partial Crystallization

Abstract

The invention relates to a method for thermally treating polyester pellets to obtain a partial crystallization, whereby the polyester melt is delivered to an underwater granulating system and granulated; the thus obtained granulates are carried from the underwater granulating system through a water-solids separator over a short conveying distance; the dried granulates are then delivered to a treatment device at a granulate temperature higher than 100 degrees C. without external energy or heat being supplied. The heat treatment leading to partial crystallization results from the intrinsic heat of the granulates, whereby the treatment device is embodied as an at least lightly inclined reactor, into which the granulates are delivered at a temperature higher than 100 degrees C., the granulates passing through said reactor from the loading point to the discharge point under their own weight and leaving the same at a temperature higher than 130 degrees C.

1 : Method for thermal treatment of polyester pellets, to obtain a partial crystallization, wherein the polyester melt is fed to an underwater granulation system and is granulated, the thus obtained granulates traverse a short conveyor distance from the underwater granulation system to a water-solids separator, the dried granulate material is then delivered to a treatment apparatus, without external energy or heat being supplied, the granulates having a temperature of greater than 100 degree C., and wherein heat treatment that results in the partial crystallization is achieved by means of the intrinsic heat present in the granulate, characterized in that
 the granulates are fed to a crystallization reactor that is at least slightly inclined, the granulates having a temperature of greater than 100 degrees C., the granulates passing through the crystallization reactor from the loading point to discharge point and then leaving the crystallization area with a temperature of greater than 130 degrees C., without energy being supplied.   
   
   
       2 : (canceled) 
   
   
       3 : Device for carrying out a method of thermal treatment of polyester pellets, in order to achieve a partial crystallization of the pellets with an underwater granulator ( 2 ) and a water-solids separator ( 3 ), characterized in that
 a reactor tube ( 5 ,  5 A), being oriented at least slightly inclined, a conveyor device ( 6 ) being arranged at the lower end of the reactor tube, the conveyor transporting the partially crystallized granulates to a silo, a solid-phase poly condensator ( 8 ), or to other post-processing apparatus.   
   
   
       4 - 7 . (canceled)