Method for Thermally Treating Polyester Pellets to Obtain a Partial Crystallization

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.