Abstract: A method of recovering a solvent including: supplying polymerization reactants including one or more monomers and a solvent to a reactor to obtain a polymer solution; supplying a stream including the polymer solution to a separator to separate an upper discharge stream including the solvent, wherein the solvent is in a gaseous phase, and a lower discharge stream including the polymer solution; heating a divergence stream including a part of the lower discharge stream from the separator by a heating device and refluxing the divergence stream to the separator; supplying a residue stream including a remainder of the lower discharge stream from the separator to a steam stripping process unit; and adjusting a vapor mass fraction of the divergence stream which is refluxed to the separator with a pressure adjustment valve after being heated by the heating device.

Abstract: A method of recovering a solvent including: supplying polymerization reactants including one or more monomers and a solvent to a reactor to obtain a polymer solution; supplying a stream including the polymer solution to a separator to separate an upper discharge stream including the solvent, wherein the solvent is in a gaseous phase, and a lower discharge stream including the polymer solution; heating a divergence stream including a part of the lower discharge stream from the separator by a heating device and refluxing the divergence stream to the separator; supplying a residue stream including a remainder of the lower discharge stream from the separator to a steam stripping process unit; and adjusting a vapor mass fraction of the divergence stream which is refluxed to the separator with a pressure adjustment valve after being heated by the heating device.

Abstract: The present invention relates to a method for preparing a polyetherester copolymer having excellent economical efficiency by recycling unreacted diol and excellent physical properties. Accordingly, the preparation method may prepare a polyetherester copolymer of high purity having excellent economical efficiency by purifying a byproduct to separate a recycle stream including unreacted diol therefrom, and reusing the recycle stream.

Abstract: The present invention relates to a method for preparing a polyetherester copolymer having excellent economical efficiency by recycling unreacted diol and excellent physical properties. Accordingly, the preparation method may prepare a polyetherester copolymer of high purity having excellent economical efficiency by purifying a byproduct to separate a recycle stream including unreacted diol therefrom, and reusing the recycle stream.

Abstract: The present disclosure relates to a method for preparing polybutylene terephthalate, and the method for preparing polybutylene terephthalate of the present disclosure recycles the recovered 1,4-butanediol, so the condensation efficiency in the condenser is not lowered. Therefore, the degree of vacuum of the polycondensation reactor is maintained, so that the preparation efficiency and the degree of polymerization of polybutylene terephthalate can be increased.