Equipment and method for producing polyhydroxycarboxylic acid

An equipment for producing polyhydroxycarboxylic acid, comprising a ring-opening polymerization apparatus for causing ring-opening polymerization of hydroxycarboxylic acid cyclic dimers, a liquid phase devolatilizing apparatus for devolatilizing of unreacted cyclic dimers or by-products with application of negative pressure while maintaining the generated polyhydroxycarboxylic acid in a melted state, and a drying apparatus for heating solidified polyhydroxycarboxylic acid for drying, wherein

• an indirect heat exchanger is connected to a vent gas discharge path of the liquid phase devolatilizing apparatus,
• the indirect heat exchanger captures a dispersed in-process substance containing the cyclic dimers and transfers the substance to the ring-opening polymerization apparatus,
• a wet condenser and a hot well are connected to a vent gas discharge path of the indirect heat exchanger and that of the drying apparatus, respectively,
• the wet condenser captures a dispersed in-process substance containing the cyclic dimers with the use of a refrigerant containing hydroxycarboxylic acid corresponding to the cyclic dimers at a concentration of 50% or more and transfers the substance to the hot well,
• the hot well causes hydrolysis of the cyclic dimers for generation of hydroxycarboxylic acid,
• the generated hydroxycarboxylic acid is mixed with the refrigerant and the mixture is circulated to the wet condenser, and
• hydroxycarboxylic acid is highly concentrated via circulation between the wet condenser and the hot well and then discharged.