Device and method for separating a cyclic diester from polymer melts

A device for separating and recovering a cyclic diester of general Formula I

• R being selected from hydrogen or linear or branched aliphatic radicals with 1 to 6 carbon atoms, from a polymer melt, comprising the diester of general formula I, which comprises
• a) at least one demonomerisation device for removing the diester of general Formula I in gaseous aggregate state from the polymer melt,
• b) at least one separation device, which is connected subsequent to the at least one demonomerisation device and which is in fluidic connection with the at least one demonomerisation device, for separating the diester of general Formula I, in which the diester of general Formula I is converted via a solid into a liquid aggregate state, and
• c) at least one device for producing a vacuum which is connected subsequent to the at least one separation device and which is in fluidic connection with the at least one separation device,
• wherein, subsequent to the at least one device for producing a vacuum, at least one condenser is connected, which is in fluidic connection with an outlet of the at least one device for producing a vacuum,
• wherein, in front of the at least one device for producing a vacuum, at least one device for producing an initial vacuum is connected, which is in fluidic connection with the at least one condenser and/or the at least one device for producing a vacuum;
• and
• wherein the at least one device for producing a vacuum is a cascade of at least two ejector pumps, the cascade of at least two ejector pumps being designed without intermediate condensation.