Method for Thermally Treating Polyester Pellets to Obtain a Partial Crystallization

The invention relates to a method for thermally treating polyester pellets to obtain partial crystallization, whereby the polyester melt is supplied to an underwater granulating system and granulated; the thus obtained granulate are fed from the underwater granulating system into a water-solids separator. The dried granulate is then fed into a treatment device at a granulate temperature higher than 100 degrees C., without external energy or heat being supplied. The intrinsic heat of the granulate is used as the heat treatment leading to partial crystallization. The crystallization device is embodied as an at least lightly inclined reactor, into which granulate is fed at a temperature higher than 100 degrees C. The granulate passes through the reactor from the loading point to the discharge point under its own weight and exits the reactor with a temperature higher than 130 degrees C.