Patent ID: 7683156

Claim:
A method for manufacturing a high-molecular polycondensate out of a solidified polycondensate prepolymer through solid-phase polycondensation, comprising at least one step for heating up the polycondensate, followed by at least one step for crystallization, at least one step for solid-phase polycondensation reaction and at least one step for cooling, wherein said step for heating and at least one of said steps for cooling involve exposure to a first process gas, characterized in that a gas outlet opening of a cooling unit is connected with a gas inlet opening of a heating unit, so that at least a portion of the first process gas heated in the cooling process releases its energy to the cold product entering the process in the step of heating before crystallization, wherein the polycondensation cleavage products obtained via the solid-phase polycondensation reaction are removed from the product by means of a second process gas, and the second process gas is then stripped from the polycondensation cleavage product and essentially recycled in an essentially closed process gas circulation at least through said step for solid-phase polycondensation reaction, wherein the polycondensate prepolymer is supplied to the process at an ambient temperature under 40° C. and the product temperature increases by at least 160° C. wherein the specific energy input measures less than 120 kWh/ton.